Volume 4 Number 2 December 1996 ISSN 1012-9812

Inhalation (breathing in) Ingestion (swallowing) Absorption (skin contact)

UNITED NATIONS CENTRE FOR HUMAN SETTLEMENTS (Habitat)I

JOURNAL OF THE

NETWORKof African Countries on

Cost-effective Building Technologies

United Nations Centre for Human Settlements (Habitat)Nairobi, 1997

CONTENTS

The aim ofthe Network and its Journal ii

Foreword v

Building Materials and Health ;........................................................................................ I

Environmental Aspects of Manufacturing and Use of Asbestos Products 9

Health and Safety in Construction 21

Publications Review 41

THE AIM OF THE NETWORK AND ITS JOURNAL

The Network ofAfrican Countries on Cost-effectiveBuilding Technologies has the objective ofstrengthening local technological capacity throughfacilitating information flow, regional cooperationand transfer ofappropriate technologies in low-cost

. and innovative housing delivery systems in Africancountries.

The Journal of the Network, currently publishedbiannually, aims at providing a channel forinformation that is available and could be used byprofessionals, teclmicians, researchers, scientists as

CONTRIBUTIONS TO THE JOURNAL

This Journal welcomes information or articlesfln low-cost innovations in building technologies.Information in the form of technical and policypapers, illustrations, news items andannouncements of events can be sent fromindividuals or institutions in the private or publicsector, from within and outside the Africanregion. All correspondence on the Journal shouldbe addressed to the Chief, Building andInfrastructure Technology Section, Research andDevelopment Division, UNCHS (Habitat), P.O.Box 30030, Nairobi Kenya.

The views expressed in this Journal do notnecessarily reflect those of the United Nations.Mention offirm names and commercial productsdo riot imply the endorsement of UNCHS(Habitat). The reprinting of any of the materialin this publication is welcome, provided that thesource is mentioned and one copy sent to UNCHS(Habitat).

National Network Institutions

Housing and Architecture DepartmentMinistry of Town Planning and HousingYaounde, Cameroon

Department of Civil EngineeringUniversity of Addis AbabaEthiopia

Building and Road Research Institute (BRRI)Kumasi UniversityGhana

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well as policy and decision-makers. It is a mediumfor information exchange and facilitator foracquiring suitable technologies and know-how byneedy countries.

Efforts are made to compile, process and publisharticles and technical papers originating, mainly fromthe African region. However, as deemed appropriateand subject to availability, research findings andtechnological information from countries outside theAfrican region are also included to stimulateinterregional cooperation as well.

Housing and Building ResearchInstitute (RABRI)College of Architecture and EngineeringUniversity ofNairobi, Kenya

Lesotho Housing and LandDevelopment CooperationMaseru, Lesotho

Department of Civil EngineeringThe PolytechnicUniversity of Malawi, Malawi

Department of Architecture and CivilEngineeringUniversity of Malta, Malta

School ofIndustrial TechnologyUniversity of Mauritius, Mauritius

Ministry ofLocal Goverrunent and HousingWindhoek, Namibia

Nigerian Building and Road Research Institute(NBRRI)Lagos, Nigeria

Faculty of EngineeringFourah Bay CollegeUniversity of Sierra LeoneFreetown, Sierra Leone

Centre Technique des Materiaux de Constructionde la Ceramique et du VerreCTMCCVTunis, Tunisia

Ministry of Lands, Housing and UrbanDevelopmentKampala, Uganda

Building Research Unit (BRU)Dar-es-SalaamUnited Republic of Tanzania

Editor-in-chiefKalyan RayUNCHS (Habitat)P.O. Box 30030Nairobi, KenyaTel: 254-2-623039Fax: 254-2-624265Email: kalyan.ray@unchs.org

National Housing AuthorityLusaka, Zambia

Ministry of Public Constructionand National HousingHarareZimbabwe

EditorBaris Der-PetrossianUNCHS (Habitat)P. O. Box 30030Nairobi, KenyaTel: 254-2-623906 .Fax: 254-2-624265Email: baris.der-petrossian@unchs.org

Cover and backpage illustrations credit: International Labour Office (!LO), Geneva.

';',

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FOREWORD

Construction industry, on one hand, plays a significant role in economic development in every country and,on the other hand, is a m~or consumer of natural non-renewable resources, a polluter of the environment,and a potential source ofhazards to the health ofconstruction workers and building occupants. The complexity,rapid increase in the volurne and the modern nature ofconstruction has however, prompted many architects,engineers and builders to produce and use certain materials and chemical which are proven to be harmful toboth environment and hurnan health.

Many of those involved in the construction were (and perhaps are) of the opinion that in order to ensure asustainable construction sector, there is a need for environmentally-sound management of non-renewablenatural resources used in the construction, and an abatement of the harmful effects of construction to theenvironment. The health aspects of the sector, however, were neglected or given a secondary priority. It isonly in the recent past that the health implications of construction sector has become a subject of concernand urgency to many agencies and scientists. A growing argument also indicates that any constructionpractice or product of construction that has harmful implications to human health can not be considered asbeing sustainable. The long-term consequences of dust, air pollution, exposure to asbestos fibres and theunsafe use of toxic chemicals in construction are few examples of such implications.

While increased awareness and knowledge ofthe implications ofhealth hazards caused by construction andbuilding materials industries have resulted in taking some action in industrialized countries, the developingcountries, particularly many countries in the Africa region, have made very little progress in arresting thissituations. Their position is even more desperate given that many ofthem do not posses adequate regulations,experience or facilities for environmentally-sound construction practices let alone the mitigation of healthhazards of the sector.

This issue of the Journal is devoted to "Construction, Building Materials and Health". It covers selectedarticles on the subject which outline among others, some strategy options and recommendations on how tomitigate the health hazards ofthe construction activities. It is hoped that the readers will find the contents ofthis Journal interesting and helpful to their work. The readers are also invited to refer to a comprehensiveresearch study entitled "Building Materials and Health" which has been produced recently by UNCHS(Habitat).

The efforts of Mr. Baris Der-Petrossian ofUNCHS (Habitat) in drafting and editing articles and producingthis issue of the Journal, as well as those who have made contributions are thankfully acknowledged.

Darshan JohalAssistant Secretary-GeneralActing Executive Director

UNCHS (Habitat)

v

i

BUILDING MATERIALS AND HEALTH*

I. INTRODUCTION

Agenda 21 adopted by the United Nations Conferenceon Environment and Development (UNCED) held inRio de Janairo in 1992, recognizes that the aciivitiesof the construction sector can be a major source ofenvironmental damage and the use ofcertain buildingmaterials can be harmfulto human health. It, therefore,recommends policies, technologies and exchange ofinformation to enable the sector to meet humansettlement development goals, while avoiding itsharmful effects to human health and the environment(Chapter 7, Programme Area G: "Promotion ofSustainable Construction Practices").

Similarly, the Habitat Agenda adopted by the secondUnited Nations Conference on Human Settlements(Habitat II) in June 1996 in Istanbul, providesimportant recommendations for govemments and allstake holders in the construction industry to enhancecapacity for environmimtaIIy sound buildingmaterials production and construction technologieswith particular attention to energy efficiency, health,accessibility and consumer safety and protection.

In addressing adverse environmental effects causedby construction activities in general, and buildingmaterials in particular, UNCHS (Habitat) has alreadypublished a document entitled: DevelopmeIrt ofNational Technological Capacity forEnvironmentally Sound Construction, (HS/293!93E). This publication which is already widelydistributed identifies ways in which constructionactivities contribute to different areas ofenvironmental stress and considers means availablefor reducing adverse environmental impacts throughimproved technologies and through design andmodified practices.

Risks to health usually result from exposure toharmful environmental conditions in the extraction,production and use of building materials, and thedisposal of related wastes. The harmful conditions

• Thisarticle has been produced by Mr. K. Msita, formerUNCHS (Habitat) staff and Mr. B. Der-Pelrossian, UNCHS(Habitat). It is based on a comprehensive research studyentitled "Building Materials and Health" which was conductedby UNCHS (Habitat) recently.

include exposures to dust, fumes, gases andvapours,and toxic metals. The interaction of thesefactors and the human organisms can be hazardousto human health in a variety of ways, includingrespiratory diseases like asthma, heart disease,cancer, neurological 'disorder, or poisoning. Theannex appearing at the end of this paper gives asummary of building materials, their areas ofapplication and related health hazards, substitutematerials and mitigation strategies on the hazards.

Tins article focuses exclusively on the health hazardsof building materials and their control. There areeight classes of materials which have beenconsidered, namely: traditiOIial materials, asbestosand mineral fibres, metals, solvents, pesticides, silicadust, radon and wastes. For a more detailed treatmentof the subject, reference is invited to acomprehensive UNCHS (Habitat) study entitled:Building Materials and Health.

II. HAZARDOUS BUILDINGMATERIALS

Traditional Building Materials

Traditional building materials include earth, stone,timber, and thatch. Generally, where the dwellingis made from low-strength masonry, the walls, andfloors are prone to cracking as the earth dries,providing suitable dark spaces for disease arthropodsto hide. Roofs made from thatch also provideplentiful hiding spaces for arthropods and can be acause of fue hazards. Furthermore, traditional flatroofs made ofpoles piled with wood and covered inlayers of mud, provide an ideal habitat forarthropods. Such arthropods include houseflies,cockroaches, triatomine bugs, domestic ticks and bedbugs. Some colonize humans and animals, whileothers breed outside the house but enter it to feed.

A number ofthese arthropods are carriers ofhumandisease pathogens. Their related diseases areparticularly prevalent in tropical areas, since highertemperatures enable the vectors to breed morerapidly. Perhaps the most important disease carriedby the vectors is the American form ofTrypanosomiasis, or Chagas' disease, which is

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transmitted by the bites ofthe triatomine bug. Peopleinfected with Chagas' disease are often unable ·towork because of the damage to their cardiovascularsystem.

Methods available to eliminate infestation include:

o Spraying the walls and roofs with insecticides;(However, it should be noted that insecticidescreate another health problems)

o Plastering with smooth durable materials; (Butthe choice of materials for plastering whichare compatible with earthen base materials isdifficult. Cement-based plasters rarely adhereto mud walls because of the differentialmoisture movement)

o crack-free materials such as fired-claymaterials, concrete products, and aluminum!iron based materials for roofing.

Timber as a basic natural product, in general presentsno health hazard in itself. However, inhalableparticulate sizes may possess toxic properties.Respirable dust of any kind can irritate therespiratory system or interfere with mucociliaryactions. People most at risk are those exposed tohigh level dust during the sanding and machineryprocess of timber products.

One ofthe best mitigation measures is the protectionof workers in the workplaces of timber processing(saw mills and carpentry/joinery workshops). Thework system must control dust from wood to levelsbelow the Maximum Exposure Limit (MEL). TheMEL for all dusts should not be higher than 5mg/m'. In some countries, the acceptaple MEL is evenas low as 2mg/m'.

Asbestos

The term asbestos coVers a number of naturally­occurring fibrous silicate materials in rockformations widely distributed in the earth's crust.However, only a few of the deposits arecommercially exploitable. Asbestos is used forlightweight insulation, filler in plastics and roofingfelts, for sprayed steel coatings, pipe seals, additiveto cement and board products, corrugated roofingtiles, water tanks and pipes, for high temperatureapplications etc.

While the properties of asbestos have been known

2

for thousands of years, it is only in the last century,that the manufacture of building materialsincorporating asbestos has been carried out on anindustrial scale.

Employment in the asbestos industry has shown astrong correlation with a number ofhealth problemssuch as asbestosis, lung cancer, and malignant tumoron the lining ofthe chest cavity or abdomen. Healthrisks are due to exposure to airborne particles thatare of such small dimensions (less than 3 micronsin diameter) as to become respirable and be depositedin the lung tissue.

The health hazards associated with the use ofasbestos in the construction industry have come toasharper focus in recent years: there has been agrowing concern and alarm about risks to dangersofbreathing fine asbestos fibres. On the other hand,there are others who believe that not enoughtoxicological and medical data are available to justifya ban on asbestos and asbestos products and that alot more research is necessary before a finaljudgement could be arrived at. It is also believedthat the existence ofasbestos related diseases reflectsneglect of working conditions in the factories andignorance regarding the science of occupationaldiseases associated with asbestos in the past.

The major risks are to the workers in the asbestos­products factories, to construction, demolition andmaintenance workers and building occupants whenthe material is cut or drilled, or'when degradationoccurs by physical abrasion or chemical attack,releasing respirable particles in the air.

Since stripping of asbestos-containing materialsoften raises exposure levels for building occupantsas well as the contractors for a considerable periodof time, the risks involved in such actions must becarefully balanced against predicted risks if thematerials remain in place. In-Situ repair work andsealing may be preferable to full-scale removal,particularly if the asbestos is in a relativelyinaccessible location. Building occupants can beprotected by confining the material in sealedcomponents.

Stringent handling regulations in the manufacture,use, transportation, demolition, storage and disposalof asbestos must be established. In view of thereported carcinogenic properties of asbestos after

inhalation, exposure via the respiratory route shouldbe avoided as far as possible. To avoid eye and skinirritations, protective clothing and spectacles shouldbe used. Employers should develop a trainingprogramme for all employees who are exposed toairborne concentrations of asbestos at or above theaction level.

Many materials have been developed as substitutesfor asbestos-based products, a number ofwhich useman-made-mineral-fibres (MMMFs). Substitutematerials and non-fibrous alternatives include:plastics, non-toxic metals, soft wood and clay.Vegetable fibres can also be good substitutes.MMMFs risks to health are related to fibre diameteras in the case ofasbestos. Their substitute materialsare the non-fibrous alternatives suggested forasbestos.

Note: For a detailed treatment ofenvironmental aspects of mining,milling, manufacturing and use ofasbestos products, refer to the nextarticle included in this Journal.

Metals

Metals are used in the construction industry in theirmetallic form or as compounds, primarily in paintsand other finishes. Lead has more uses in roofingand associated works, water supply pipes,glazingbars and as an additive in linseed oil putty. Mostmetals are harmless, in fact, dietary intake ofmanymetallic elements is essential to health. Riskshowever result from excessive intake of certainmetals. The principal building-related sources ofhealth risks are: soluble metallic salts in watersupply, from the use of metals in pipework andjoints, storage tanks, and roof flashings, gutters anddownpipes where run-off water is used for cookingor drinking; and paint flakes, which may be ingested.

Metals ofpotential concern are cadmium, chromiumand lead. Their health risks include: bone damageand kidney malfunction, skin diseases, inflammationof the larynx and perforation of the nasal septum,liver damage, and lung cancer, and poisoning. Allthe three metals present risks as they are used incompounds of paints. Further health risks areexperienced in cadmium - plated fittings, andchromium metallic finishes. Children areparticularly liable to be affected by toxic metalliccompounds in paints as they spend a large part of

their time at floor level, where they are susceptibleto paint and solder flakes in household dust.

Furthermore, some children develop a conditionknown as "pica", characterized by a craving to eatnon-food substances. Paint flakes can be-a favouritemeal. To minimize risks to exposure, toxic metals­based paints should never be used in situationsaccessible to children. Paintwork should be kept ingood condition. In removing old toxic metal-basedpaints it is advisable to use chemical strippers ratherthan mechanical methods, and all debris fromstripping such old paints should be safely clearedand disposed. Any paint containing lead, chromiumor cadmium should be clearly labelled with theircontent of these metals as wet film and dried paint.

Substitutes for these materials include non-toxicmetals, plastics, synthetic rubber, timber and forpaints it is recommended to use, vinyl-based paints,polyurethane varnishes and water based paints.

Solvellts

Organic solvents are very widely used inconstruction as key ingredients ofadhesives, paints,flooring materials and mastics. The most commonlyused solvents include white spirit, toluene, xylene,tricWoroethane, styrene and carbon tetrachlo~ide.

Paints, glues and lacquers contain toluene, methyl­n-butyl ketone, n-hexane and xylene. Paint strippersand solvents contain white spirit anddichloromethane; and expanded plastics containstyrene. All these materials are volatile and therefore,can build up in the indoor environment duringconstruction and maintenance work. Moreover,their emission can continue even after_ occupancy,and thus add to the load ofother solvents and organicchemicals in the environment from dry cleaning,aerosol propellants, correction fluid, cigarette smokeand so on.

If inhaled in sufficient quantity, all solvents canproduce sedation effects ranging from slowedreaction time and decreased vigilance to anaesthesia.Some produce irritation to the eyes, nose and throat.Several can cause liver damage and harm the nervoussystem (I). Studies have revealed that the majorhealth hazards for painters include: occupationalcancer resulting from exposure to benzene andcarbon tetrachloride which can cause leukemia andliver cancer respectively. While the solvents are inuse, during construction activity, levels will clearly

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reach much higher values over a shortperiod oftime.Adequate protection of workers from excessiveinhalation through proper ventilation and ifnecessary protective clothing are therefore,recommended. Workers need also to be providedwith health and safety infonnation about the hazardsofthe solvents including the minimum requirementsfor safe use and exposure control to protect theirhealth, the chemical ingredients, the short and long­tenn health effects, first-aid information, storage andtransport requirements.

During occupancy, the key consideration is not theexposure or limit value ofanyone organic chemicalbut the exposure to all volatile chemicals. There arelimited options at present for the' substitution ofvolatile organic chemicals in paints and otherfinishes. Alternative water-based paints are availablewhich reduce the quantity of organic chemicalsolvents, but although advertised as environmentallyfriendly, they do contain significant quantities oforganic solventS' and a range of other hazardouschemicals. Solvents based purely on natural productsdo exist (2), but are not manufactured yet in largequantities and paints based on them are notcommercially available.

Pesticides

A very large group of organic chemicals are in use aspesticides and fungicides for timber treatment. Theyinclude dieldrin, lindane and benzene hexachloridecommonly used as insecticides, andpentachlorophenol commonly used as a fungicide (3).All ofthese chemicals are toxic to the organisms theyare intended to combat. If inhaled or ingested insufficient quantities, they can also be hazardous tothe health of those involved in applying them,particularly vyhen used in the fonn of sprays. Somecan cause skin reactions. Several of them have beenshown to be carcinogenic. (4, 5). The principal riskfrom pesticides is to construction workers, and tothose involved in the remedial treatment of timber inexisting buildings which has been degraded, and inpoorly ventilated roof spaces, and using sprays (5).

While exposure to individual organic chemicals inthe indoor atmosphere may be acceptably low, thecombination of numerous gases and vapours at lowconcentrations can have irritant effects. There is agrowing school ofthought that pesticides are not anefficient long term approach to the preservative

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treatment of timber, because they penetrate thetimber only to a limited extent, and are ,graduallylost to the atmosphere. Because offthis limited life,the contribution claimed by pesticide manufacturersto stemming deforestation by reducing futuredemand for timber has been challenged (5).

One of the mitigation strategies is to eliminate bydesign the condition which pesticides are used totreat. Rotting of timbers can only take place underconditions of high humiditY; it can be reduced oreliminated by: seasoning timber before use to reducemoisture content ensuring all timber in building iskept at low levels of moisture, by providingventilation of underfloor and roof spaces, makinguse of timber species which are less susceptible torot, and reducing the use of the more vulnerablesapwood. Likewise, where pesticides are commonlyused for protection against tennites, they should bereplaced where possible by the use of physicalbarriers to entry, or by making use of naturallytermite-resistant species (6).

Radoll

Radon is a radioactive gas and is ubiquitousthroughout the geosphere, biosphere and atmosphereand occurs in several isotopic forms. Radonsubstances are present in all surface soils and rocks,but in concentrations which vary regionally as afunction of the relative abundance of the parenturanium. It has been identified that Radon is thelikely cause ofincreased rates oflung cancer amonguranium miners.

It is capable ofdiffusing through soils, and to a lesserextent building materials, and thus entering theinternal envelope of a building. Building materialsmay also constitute a significant source, theseinclude natural stones, principally those of igneousor volcanic origin, industrial wastes likephosphogypsum - a byproduct of the manufactureofphosphate-based fertilizers, - and concretes whichcontain aggregates of similar origin.

Radon concentrates mostly in the basements ofair­tight buildings. Control measures are the extensiveventilation. Some ofthe techniques used to mitigateindoor radon levels due to infiltration from theground can be useful in the case of radon-emittingbuilding materials. For example, natural ventilationor cross-ventilation can be encouraged. Mechanicalventilation systems can be adapted to give a slightlypositive indoor pressure, or at least to keep negative

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pressure differentials to the minimum required forefficient operation of the ventilation system.

Substitute materials are those with no or low levelsofradon emission like sedimentary stones (sandstoneor limestone). Alternative walling constructionscould use brick, adobe, timber framing or concreteblock. Substitute materials for plastering couldinclude cement-sand render or mud-based renders.For existing buildings, however, the most effectivemitigation strategy is to isolate radon-emittingmaterials from the indoor environment. This couldbe achieved with a dense layer of internal render.Moisture barriers and especially air-tight barrierssuch as polythene sheet can be incorporated in thewall construction. Special surface coatings have alsobeen developed to inhibit radon emission.

Silica dust

Silica refers to naturally occurring materialscomposed ofsilicon dioxide (sio,). Silicate mineralsare the largest group ofnatural minerals with varyingcomposition but all contain silicon-oxygentetrahedra as structural components. They areubiquitous in the earth's crust in both crystalline andamorphous forms. The presence of silica in theenvironment results from natural processes and fromhuman activity. some ofthe uses ofsilicate mineralsassociated with construction include: manufactureof both glass and ceramics; incorporation intoabrasive, such as sandpaper, and sandblastingminerals, in filtering equipment for water andsewage-treatment systems, furnace linings and beds,filler in paints, plastics, asphalt and cements (finelyground sand), construction purposes (such as roads,earth dams, concrete works).

Occupational exposure to silicate materials leads toa form ofscarring ofthe lungs called silicosis, which·interferes with breathing and obstructs the circulationthrough the lungs.

Occupational exposures to silica dust occur in manydifferent industries and under a wide range ofCircumstances which include mining and quarryingoperations, production ofglass, cement and ceramics,granite and stone industries, and constructionactivities generally (e.g. earth based constructionactivities, production of concrete and bricks).

The prevention of silica dust-induced diseases isimportant considering its harmful effect to humanhealth. It is important: to prevent the formation of

dust as far as possible; to suppress its sourcewhatever dust is inevitably formed, and to provideprotective equipment to workers for preventinginhalation of dust.

Wastes

As a result ofrapid industrialization, there has beena marked increase in the generation of wastes. Onthe other hand, measures for the utilization ordisposal of such wastes lag behind compared to theamount of wastes being produced. Some of theindustrial wastes produced are hazardous both to theenvironment and to human health. Specific healthhazards which arise during the production and useofbuilding materials, in the demolition and disposalof building wastes are due to: gases and vapours,dusts, toxic metal-based products, asbestos, pests anddisease vectors which may have inhabited indemolished buildings.

Considering the health hazards which can result fromwastes, the collection and proper disposal ofconstruction wastes is essential for the preventionofdiseases and injuries. Generally hazardous wastesshould not be abandoned. They should be disposedof safely, and wherever possible, at the expense ofthe generator. Options available for dealing withwastes include:

o Incineration treatment;

o Secure land disposal; and

o Waste minimization through source reductionand recycling.

TIl. CHALLENGES FORCONTROLLING HEALTH HAZARDSSSOCIATED WITH BIDLDINGMATERIALSThe challenges in promoting practical strategies forcontrol ofhazards associated with building materialsinclude:

o Insufficient knowledge regarding the natureand severity of health hazards of somematerials. The health effects of chronic low­level exposure to many materials remain verydifficult to assess (7). This raises issues suchas: ths: problem ofthe burden ofproofto makelegaf-political decisions, differences ofperception of what is just or fair in publicpolicy, what are the appropriate threshold

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limits in the public eye, whether to prohibitthe use of a material until it is proven safe, orto allow its use, until it is proven harmful.Furthermore, the public is not adequatelyinformed of the health hazards of buildingmaterials.

o Manufacturers of building materials havedifficulties of balancing the immediate costsof health improvements against long termbenefits. The uncertainty of future benefitswould make it less likely that action would betaken. Thus, short-term considerations areusually on the winning side.

o Designers often have a number ofconflictingcriteria to resolve. They need to balance therisks to health against the cost of providingprotection. For example, the need for adequateventilation for a healthy indoor environmentwith the need to reduce the energyconsumption in heating or cooling incomingair.

o One of the control strategies involves the useof alternative materials. Alternatives,however, are not available in all situations.Also alternatives which were at one timerecommended could have their own separatehazards, particularly when the substitutionoption is new and untested. Consequently,avoidance of one type of risk may simplyintroduce a different and perhaps lessunderstood type of risk.

o There are no regulatory mechanisms on someof the hazards, partly due to lack ofinformation or due 'to economicconsiderations. Where regulations exist,administrative costs and bureaucracy involvedin implementing acts are severe disincentivesto their application. It needs also to be notedthat in many countries, regulations are still farbehind current practice.

o Inadequate collaboration among the broad­range of stakeholders and actors, particularlyamong research institutions, the constructionindustry and regulatory bodies.

o Additional features for developing countries,include: lack of manpower and local trainingopportunities; poor information base and

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inadequate dissemination of availableinformation; lack of, appropriate policies;existence of such laws which do not cover allaspects of workers health and welfare and/orare biased towards curative rather thanpreventive health care (8, 9).

IV. CONTROL STRATEGY

It is not intended to propose, within the confines ofthis paper, a specific approach for the control ofeachof the discussed building materials-related healthhazards. However, the following general healthhazard management approach is recommended:

o Phase out hazardous materials and processesand use safer alternatives;

o In cases where phasing out is not possible andthere are no safer options, then hazardousexposure levels should be minimized andcontrolled through engineering measures;

o Those at risk should be protected by the useof protective. equipment, application of safework practices, and provision of medicalservices;

o Arrange for health insurance policies to coverthose at risk; and

o Continuously monitor the risk and providemedical surveillance of workers.

The success of these measures require the co­ordinated action of the industry, governments, andinternational agencies to ensure that the problemsof human health related to building materials andthe built-environment are linked' to the GlobalStrategy for Shelter, the Agenda 21, the HabitatAgenda and all global or national rules andregulation.

To reduce the impact of health hazards associatedwith building materials industry, possible lines ofactions for different actors are outlined below:

V. .ROLES OF KEY ACTORS

The UNCHS (Habitat) study on Building Materialsand Health identifies roles to be played by keyactors in health hazard control. The roles for theproducers and users ofbuilding materials are brieflyproposed to be as follows:

o Manufacturers should take measures to avoidthe production of hazardous materials andensure the protection ofworkers and users oftheir products;

o Designers should specif'y safe materials anddesign the indoor environment such thatconcentrations ofhazardous substances do notaccumulate;

o Owners of buildings should ensure that theyuse safer materials and processes inconstruction ofbuildings, during maintenance,refurbishment, demolition and disposal of

.wastes;

o Builders should ensure they offer protectionto workers during construction, maintenance,demolition and disposal of wastes;

o Research organizations should work towardsbridging the knowledge gap regarding healthaspects of building materials;

o Professional organizations and non­governmental organizations should spearheadhealth advocacy, provision of information,standards, promote technology developmentand diffusion, health education and trainingand monitor the implementation ofregulatoryand control programmes;

o Workers themselves should assume a greaterrole in self-monitoring the quality oftheir ownwork environment and should act responsiblyby: taking reasonable care for their health andsafety and those who may be affected by theiractions, and comply with occupational safetyand health standards and all statutoryprovisions which are applicable to their ownactions and conduct.

o Awareness creation campaigns should beencouraged so that producers and users ofbuilding materials are aware ofhealth hazardsassociated with their actions.

alternatives available for the substitution ofmaterialsharniful to health and the possibility of introducingproduct changes should be considered to discouragethe use of harmful materials. Local governmentsshould ensure that building regulations are mademore restrictive to the use of harmful materials inbuildings. Non-regulatory actions may includegovernment sponsorship ofresearch, the promotionofstandards and specifications and the organizationof demonstration proJects.

REFERENCES1. Ray, D. E., "Hazardsfrom solvents, pesticides

and PCBs " in Leslie, G. B. and Lunau, F. W.,Indoor Air Pollution: Problems andpriorities,Cambridge Uni;yersity Press, Cambridge, UK,(1992).

2. Ashworth, J., "My paints ", Architects'Journal, 27 October, 1993, p.62.

3. CurweIl, S.R. and C.G., Hazardous BuildingMaterials: a guide to the selection ofalternatives. E. & F.N. Spon, London, March1986.

4. Robertson, A., "Gases, vapour and !nists ", inBuilding and Health: the Rosehaugh guidr; tothe design, cons/ruction and management ofbuildings, RJBA Publications, London, 1990.

5. LHC, Toxic Treatments: Wood PreservativeHazards at Work and in the Home, LondonHazards Centre, UK, 1989.

6. KEP Architects, Rammed Earth Structures:a Code ofpractice (draft document), 1994.

7. Ashford, N.A., Crisis in the Workplace.Occupational Disease and Injury, The MITPress, 1996.

8. WHO, Technical Report Series 718:Environmental Pollution Control in Relationto Development, 1985.

National and local governments have a crucial roleto play in the control of hazards associated withbuilding materials by providing economic incentivesand taking regulatory and non-regulatory actionsappropriate to specific country contexts. Economicincentives should be directed to popularize the

9. East African Newsletter on OccupationalHealth and Safety Supplement 1/1990:Proceedings of the East African RegionalSymposium on Regulations and Control inOccupational Health and Safety, Zanzibar,Tanzania, 4-7 December 1989.

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ANNEXBUILDING MATERIALS AND HEALTH

A summary of building materials, their areas of application and relatedhealth hazards, mitigation strategies, and substitute materials

Material

I. Asbesl05

2. Tuxie melll]s (cadmiumchromium, and lend)

3. Solvcnt5 (e.g. toluene,xylene, diddoromethllllc,cte.)

Appllcalilin

Roofing sheets, ceiling Illes, light~ight Insulation Imd lagging, fillerIn plnstlcs and roofillg fcl15 for sprayedsled coatings, pipe senls, additive 10a:ment lind board products, and Jorhigh lempcr.llurc lIppll>:allonJ

.. In compounds of palnu ~nd metallicfinidlC~5; Dlher uses of It'lld Include:"Oller pipes, gluing bars for windllWl,and roofing Illisoclated \"Orb

USWIllI key Ingredients of IIdheslvu,flooring mnu:rinls llllli ffillllliCJ

lIealth 1Iazart15

Asbest05ls, lung t:ancer, andmalignant tumor on the lining ofthe chcst t:avity or abdomen(mcsolhelioma) and allergic rcspollSCS

Inflammalion of larynx, perforation ofnnsal septum, lead polsooing relatc.rlcerehml edema, al1llCmia, etc.

Sedation effeclli (slowed reaction time,decreased vigl1D.11Cland allD.C!lhcsia),liver damage, damage of lhe neI'Wussyslem, irrilillion and allergic rcsPOlt!CS

Millgalilln Sll'1Ilegil$

Estllhli5h and enfolU: strici n:gulatinllllfor engineering control mCl1!ures, andsafe work pmcllces In the manufactun:,usc, and handling of ashestOli

Provide for substllutlon of Il!ihestOli when:safe controls can not be assun:d

All minernl fibtc-based suhstitule5,particularly MMMFs, should be 111ve!i1lgaledfor their effect 00 healthSeal all lJulillied componenlli CllntllinlngasbcstOli or MMMFs

Label lead, chromium or cadmiumbased paints iodicating umultllble uses

Amid paints conlilinlng lralc-meliliinsituatlollll aa:essible to children

Keep relaled paintwork In goodcondition (10 lIVllld flaking)COYer old paint with alternativew.tter·bllSCd vlnyl·bnllcd paints

Amid oc::upnllonal hlllafl1s, usc protectiveequipment iI.IId etl!iure good ventllalion

Substltu~ Mat~rials

Non-fibrous materlllls like non-toxic melill!i,sofllWDd and clay products, vegetable fibrematerials, and man-made·mineral fibres.(The health effects of all substitute fihn:materials should he illVClitigntctl thoroughlybefore usc).

V1nyl·bll5ed paints, water-bued palnlll,polyurethalte varnishes, non Inxlc metalproduclli aod plll5tic products

Limited D(ltiollll arc m'lll1nble at present;water-bued palnlli reduce quantity ofoTgllnlc chemical solvenlll

4. lruectlt:ldes & fungit:ldes limber ltelllmcnl(e.g. aT5cnit:, dieldrin, lindane,pCllmchloruphcnol. en:.)

Allergic responses, affeclll nervous5}'5tem, skln/olher CDlleen

Usc timber species which are less sU5ccptibie At present then: are no viable substitutes totn rot, and reduce tile usc of more vulnernble lmecticides and fungicldcsSllpl'tOOd. SCl1!on tlmher hefon: usc, keeptimber species at 101'1 levels of moisture,provide ventilation of under floor androof spaces

S. Rllndon

6, Enrlhen and traditionalmaterials

7. SiI!t:a dust

Nlllur.llly prucnl in Jolls, rocks lindIn some of the building llUItetlals likennlurnl slOIlC.!l of Igneous or wlt:ardcorigin, and Industrial WiUle5 such a5

phosphogypsum and blll5l-furnnce slagror plnllterlng • me cement-sand render

Flooring, w.llIing and roofing

Manufnc:ture of gllW, ceramic, ,SIlnd paper, sand blll5t1ng,furnnce lining, filtering, Cllncrelework, etc.

In producing TCC)Clcd materials.Reusing demolished materlllis

Lung c:ancer

rosed by di5ca:se vecton (examplcs:Chngas' disell5e, plague, typhus,relapsing fever, etc.)

St'lll'l'ing of lung (silicods),brcnihlng problems

Volpour, dUSlll, toxic metal-bll!iedpmdUClll CDn hllVC health ImpliCDIiollll

bolate radon-cmittlng materials from theIndoor environment through usc of: denghtytl3 of Ililernal render, moisture barrlen5uch nlI polytheoc 5hccl.'l, and 5peclalsurface COlltlngs

Plaster walls and mofs with smooth dumblematerials, and 5pmy walls and roofs withhuecticidcs

Prevellt formation of dwt If p05!iible

Provide prolective equipment In workel3

00 not abandon hllZOlJ'dnus waste.Oi5pC$C it safely

Usc protective equipment dutlngdemoli5hlng of building!

Usc materials with IIlW levels of radonemluion like 5cdlmeolilry rocks (salll!stoocand llm~tone). For w.llJing, we bricks,Mohe, limber framing or concrete blockswltll scdimenlilry rock nggregnle5.In replacing gypsum blllicd mortnr

Usc durable, smooth, cnu:k-free materialssuch as fired-clay producu, ClInctcteprodUClll, aluminium and Iron bll.5cdmalerlals ror roofing

At present there lITe no suitable 5ub5titUtes

Source: UNCHS (Hahltat),Building Materials and Health, 1997, HS/4S9/97E, ISBN-92·1·131·3384

8

ENVIRONMENTAL ASPECTS OFMANUFACTURING AND USE OF

ASBESTOS PRODUCTS**

ABSTRACT

Some concern has been expressed over the healthhazards associated with the environmental asbestos.This concern has been created partly due to lack ofknowledge, by some people, of recent researchfindings and misconceptions related to levels ofexposure to environmental asbestos. Environmentalexposure to ambient asbestos by the general publichas always been extremely low compared to,occupational exposures. Moreover, generalenvironmental exposure has been decreasing withtime. Many years ago there were some recognizablehealth effects associated with uncontrolledenvironmental exposure to amphiboles, tocrocidolite and to amosite asbestos.

This paper focuses mainly on various sources, types,extent, health implications, monitoring and controlofenvironmental asbestos. The paper gives attentionto the natural sources' and the old methods of theuse of asbestos. It also discusses the consequencesofthe small release ofasbestos from asbestos-cementand other asbestos products which are in use today.Reference is made to the emissions ofasbestos frommining, processing, manufacturing, transportationand waste disposal which ifcontrolled properly, aremuch lower than in the past. The paper reveals thatthe risk ofbeing exposed to environmental asbestosappears to be extremely low. However, propercontrol measures should be adopted and followedto minimize fibre-release into the environment.

INTRODUCTION

The natural mineral asbestos has been and is likelyto continue to be used widely in various productsbecause of its extremely useful and uniqueproperties. In 'mining, processing, productmanufacturing, use, and ultimately the disposal of

•• This is an edited version of a paper produced by Dr.Brian Commins, Environmental and Pollution Consultant,United Kingdom,

asbestos and materials containing it, some asbestosfibres are released to the environment. Because ofthe known danger's of the high occupationalexposures to inhaled asbestos dust in the past,concern has been expressed regarding effects ofexposure to environmental asbestos as well. (1-8).

In asbestos-based products, most asbestos fibres areattached to cement and other particulate material,or 'locked-in' to plastic, asphalt or resin. However,certain number of fibres in some products arebecoming inevitably "free" (1-6). Most asbestosfibres released to the environment are either too largeto be inhaled or are so small in size that they are oflittle health consequence (3-5). Nevertheless, acertain number offibres will be respirable and a largequantity of respirable fibres with critical size range(longer than 5 microns and less than 1.5 micronsthickoess) could pose health risks (1, 3, 5). Asbestoshas, probably, been one of the most extensivelystudied single substance (in relation to its effects tohuman health) on which numerous reports andreviews have been published by international andauthoritative bodies, including several by the WorldHealth Organization (WHO). Thus, it has beenpossible to identify the sources and nature ofasbestosfibres, and to assess the significance of its impacton human health (1-10).

There is a great deal of confusion andmisunderstanding regarding various facets ofasbestos production, types and forms ofasbestos use,sources and extent of contamination and inparticular, the significance and the health impact ofexposure..

With regard to the impact ofoccupational exposure,studies have revealed that various lung diseases haveresulted from the heavy exposures to asbestos dust

. in various situations (1-8). In early 1950's, alreadysome concern was expressed regarding certaindiseases related to occupational exposure to asbestos(asbestosis, lung cancer, and mesothelioma). -Inaddition to health problems associated with directoccupational exposures, some cases of

9

mesothelioma were recorded in the past, which wereas a result of heavy exposure to dust brought homeon worker's clothes which affected some housewives(l,8). Despite the vast differences between exposurelevels inside factories in the past, where healtheffects were clearly disproportionate, concern hashowever, been expressed regarding the health riskfor the general public. Such concern has been largelyunwarranted (3).

In order to evaluate the health effects ofexposure toasbestos, considerable amount of animaltoxicological tests has been carried out. There isnow strong evidence that only fibres greater than 5microns long are pathogenic (l; 3-5), and substantialquantities need to be inhaled (or inplanted inanimals) to induce effects, including cancer (1). Itis also worth noting that most fibres in the generalenvironmental ambient air are less than 5 micronsin length (3,5).

Studies on occupational exposure indicate thatmesotheliomas have seldom followed exposure tochrysotile asbestos only (l). Many, but not all, ofmesothelioma cases have a history of heavyworkplace exposure to amphibole asbestos"(principally crocidolite, but also amosite) eitheralone or in chrysotile mixtures (l). There is a verystrong evidence that a number of other naturalmineral fibres can cause mesotheliomas. Forexample, the mineral erionite has caused endemicmesotheliomas in some localized regions ofTurkey(l). Other factors such as exposure to certain viruses,radiation and specific chemicals, seem also to beassociated with occupational exposure to asbestos,this form of cancer is induced by exposure to anumber of chemical substances associated withchromium, nickel, isopropyl alcohol manufacture,and coal gas production (3). Smoking has a veryhigh risk of lung cancer, and research has shownthat the combination of occupational asbestosexposure and smoking substantially increases therisk ofthis form ofcancer (1). Lung cancer can alsooccur due to exposure to natural radiation.

SOURCES OF ENVIRONMENTALASBESTOS

As a result of widespread use of asbestos andproducts containing it, inevitably, asbestos fibres willbe released to the air, water and soil (l). In addition

10

to man-made sources, some natural sources ofasbestos (weathering of rocks) have significantlycontaminated the environmental air. Water can alsobe contaminated if it comes in contact with naturalsources of asbestos-containing rocks. It has beenstated by the World Health Organization that "thetotal amount ofasbestos emitted from natural sourcesis probably greater than those emitted from industrialsources" (l). It should be, however, mentioned thatenvironmental contamination in the past was muchhigher because of the limited control measures inexistence at the time.

Many potential industrial sources of asbestos havebeen investigated in the past and in most cases littleevidence of significant release of fibres has beenregistered (2-6,8,9). However, there are certainsources of asbestos release which has createdparticular concern. These are:

• asbestos brake-linings;• asbestos-waste disposal;• industrial emissions and mining

activities;• asbestos in buildings;• shipyard activities;• do-it-yourself activities involving the

use of asbestos products; and• re-Ioading ofdeposited dust-containing

asbestos (2,3,5,6,9,10).

Although questions have been raised regarding theseissues, based on investigations (2-5,8,9), it has beenshown that, where adequate control is maintained,the relatively low emissions to the environment arenot considered to be of any undue significance tohuman health.

With regard to present-day emission, it should benoted that much of the asbestos released to the airwill not be inhalable because of the relatively largesize of the general dust and other particles to whichthe fibres are commonly attached (3). This is,particularly, the case once asbestos has becomedeposited and any dust subsequently re-entrained.Some asbestos products are coated making itextremely difficult for any asbestos fibres to bereleased. The firm binding of asbestos in asbestos­cement products also minimizes fibre released to theair. Some forms of asbestos, especially chrysotile,will gradually become degraded naturally by theaction of water (2, 3, 9, 10). At the very high

frictional temperatures, for example in brake lining,where asbestos is used, much of the asbestos ischanged to innocuous amorphous material, and inany case, most of the fibres are'so short that makethem ofno biological importance (5).

One problem of importance, which requires greatattention is the removal ofold asbestos from buildings,especially where amphibole asbestos is present, andthe demolition of buildings in which substantialamounts of old asbestos may have been used. Itshould be stressed that proper control of theseactivities needs to be uiJdertaken in order to preventany undue environmental contamination (2, 11, 12).

MINING, MILLING ANDMANUFACTURING OF ASBESTOSPRODUCTS

During mining ofasbestos ore, which often is carriedout in open-pit, some asbestos will be released intothe environment. Release of fibres to the air canoccur during drilling, blasting, loading broken rockand transporting the material to the mill. In manycases, the general environmental impact isinsignificant since mining is, often, carried out farfrom settlements and also because much of theasbestos is released. in form of coarse dust whichsettles out fairly quickly. In contrast, during millingprocess which is done in closed milling areas, verylittle fibre is released to the air because of theexistence of good operational controls. Within themill building, the exposure to the workers isnowadays at a low level, although years ago themilling processes were extremely dusty (1-3, 8).

Further, the asbestos products being currentlymanufactured are such that the release of fibres isgenerally at acceptably low levels as far as workersareconcemed. This in turn reflects the .fact thatprocess-emissions to the general ambient outdoor airare also very low, This is true largely because ofimprovements ofworking practices over the years andthe existence of, as well as adherence to properregulations in many countries. Most manufacturingprocesses are nowadays carried out as 'wet' processeswhich minimize release of asbestos fibres to the air(12). Asbestos textile production is potentially oneof the dustiest of all manufacturing processes.Therefore, special attention needs to be given to dust

contrpl where such processes take place (1).

USE OF ASBESTOS

It has been estimated that some 3000 areas ofcommercial applications for asbestos are available,the most prominent ones of which include: (1, 12):

a) As reinforcement in cement based boards,pipes, roofing ,sheets/tiles and in plastics orrubber

b) As components ofbrakes and clutches for cars

c) As fibres spun and woven into cloth or ropefor insulation purposes

d) As coating to provide fire resistance in shipsand in structural elements, on pipes andboilers, (in the past)

e) . As heat insulation for pipes and boilers (in thepast).

The largest contemporary application areaworldwide, is the asbestos-cement products (1).Chrysotile asbestos is now used in practically allcommercial applications or products although smallproportions of amosite and/or crocidolite aresometimes incorporated to improve efficiency inasbestos-cement production (1-3). At present theworld's production and usage ofamphibole asbestos(amosite and crocidolite) is less than 3 per cent ofthe total asbestos produc~d (12). Amphiboleasbestos has been, and stilI is, declining in use.Chrysotile asbestos has always been, and willcontinue to be the main source ofasbestos worldwide(1, 12, 13).

Further, contemporary asbestos products are non­friable and the release of asbestos fibres to theenvironment during the transportation, installationand use (including subsequent weathering/abrasion)is af an absolutely minimal level. In the past, thesituation was very different and the quantities offibres released to the environment were frequentlymuch higher (1, 2, 8).

REMOVAL OF ASBESTOS ANDDISPOSAL OF WASTE MATERIALS

Old asbestos products including, in some cases,

11

\

'pure' free asbestos may need to be removed. Thismay be related to repair work or when substitutionby alternative materials is required, or when asbestos

removal is warranted prior to a building beingdemolished or a ship being broken up; Some of theold types ofasbestos products can create considerablevolumes of dust when they are demolished. In suchcases, special control measures are required (2, II).

. By comparison, modern-day asbestos products whendisturbed or removed should cause the release ofonlyminimal quantities of dust. In both cases, asbestosremoval must be carried out with proper control (4,11). With regard to disposition of asbestos waste,various codes of practices are in existence which

I ... .

describe the procedures of carrying out the work.Following the guidelines described in these codeswould, obviously, result in an absolutely minimalrelease of asbestos to the general environment (11,14, 15). These procedures relate to bagging,transportation and disposal to landfill of wastematerials. Asbestos waste from product manufacturealso needs to be disposed of. In recent times, becauseof(a) the nature ofproducts and their use (b) the wetnature of much of the waste materials, there is verylimited contamination of the general environment aslong as the codes of practices are followed strictly(11-15).

ASBESTOS LEVELS IN THEENVIRONMENT

contains around 0.2 to 2 million fibres per litre (9,17-19). Natural contamination levels in somewaters, for example in Canada, have been reportedto have levels of up to several hundred of millionsof fibres per litre (8, 17).

MONITORING ASBESTOS IN THEENVIRONMENT

In order to be able to detect asbestos in theenvironment, the use ofan electronic microscope isessential(5). This analytical technique is capable ofmaking the individual asbestos fibres (as small as0.0 I microns diameter and O. I microns long) visible.Fibres detected in the environment are typicallyabout 0.1 to 0.2 microns in diameter and 1-2 micronsin length. Individual fibres are of extremely smallmass being well below one millionth of a gram. Asmaller proportion of larger fibres may also exist.The sampling and analysis for environmental levelsofasbestos requires considerable expertise to providereliable information on environmental levels. Levelsin environmental air are very much lower than thosein occupational situations (1,2, 8). Therefore, opticalmicroscopic methods can· be appropriate enough tomonitor the occupational contamination levels oftheair (3,5, II).

CONDITION OF ASBESTOS IN THEENVIRONMENT

Asbestos fibres released to the air will disperseaccording to:

According to the size of asbestos fibre and thesources from which they are generated, tlle fibreswill disperse into the environment in various waysand will remain there until t1ley become diluted forlonger or shorter periods depending on localconditions.

Amphibole fibres which are only a fraction of thetotal asbestos used are more resistant to attack bynatural and industrial factors. Chrysotile asbestos,the most common type, can be partly o~ perhaps fullydegraded by weathering processes over a period oftime (I, 3, 9).

Asbestos fibres can be detected outdoors as weil asin indoor air. Recent evaluations of the availabledata indicate tllat indoor levels, on average, do notdiffer significantly from those of outside air (3,5).A long-term average concentration, representativeof many years of exposure and taking into accountindoor and outdoor conditions, appears to be in therange of0.0002 to around 0.001 fibres, greater than5 microns-long, per mI. air, with an averageconcentration of about 0.0005 fibres per mI. air (3,4, 7, 9, 16). Some of this asbestos releases arisefrom natural erosion. In urban areas, however,asbestos found in the air is mainly from the generalusage of asbestos. It would appear that ambient airlevels detected in the recent years are lower thanthey used to be some years ago.

Regarding exposure to asbestos in drinking water,the typical potable water (including situations wherewater pipes are made out of asbestos-cement)

12

a) their aerodynamic properties which areprimarily a function of fibre size and shapeand the external materials and how they areattached to the fibres, and

b) Prevalent meteorological factors, especiallythose related to wind and rainfall.

Some fibres will easily fall from the air and will be.deposited on the surfaces in the ambientenvironment. This process occurs primarily to those

. fibres which are large and heavy and in general non­inhalable. Some fibres will stick to the surfaces (e.g.walls) due to certain adhesive properties related toparticle-charge effects (3). Other fibres can bewashed out by rain. This is one ofthe most effectiveprocesses for particle-removal ofall types whatevertheir composition may be. Finally, the very finestparticles containing inhalable asbestos can bedispersed into the air as a result ofwind and thermalcurrents and become gradually diluted in theatmosphere and finally scavenged from the air byvarious means. Although the airborne-lifetime ofasbestos particles is variable, .in most cases theybecome diluted in the air rapidly. Relatively fewfibres are likely to remain suspended in the air forperiods oflonger than few days (3, 10).

Many particles, whether they contain asbestos or not,will ultimately be washed out by rain to drains,sewers, ditches, streams, etc., or to the soil. In manyparts of the world, any asbestos which might bewashed out by rain may then enter rivers andsubsequently find its way t6 the oceans. someasbestos fibres may be absorbed into soil but in mostcases, it would be very difficult for them to becomereadily detached again (10).

As far as the impact of asbestos in the environmentis concerned, the only issue of importance to beconsidered is related to implications to humanhealth.

HEALTH IMPLICATIONS OFENVIRONMENTAL ASBESTOSIn order to assess the impact of environmentalasbestos to health, it is important to clarify: whathappens when humans become exposed to it, i.e.when fibres are inhaled or ingested (1). There isoften considerable confusion relating to theinhalation of particles of any type which enter therespiratory system. It should be borne in mind thatonly absolutely minute particles are capable ofentering the deep, pulmonary regions of the lungitself. Only fibres of aerodynamic equivalentdiameters ofless than about 3 microns (3/1 000 of acentimetre) can normally penetrate to the lower

bronchial and alveolar regions of the lungs (3,10).Fibres longer than 200 microns (1/5 ofa centimetre)are very unlikely to reach the terminal air spaces(1). Many inhaled particles are immediately exhaledagain because they fail to become deposited. Largerparticles which enter the upper parts of therespiratory system are controlled by a most ingeniousnatural and very effective biological removalmechanism, this mucociliary clearance mechanismtransports fibres up t6 the upper respiratory tract andare either swallowed or expectorated (10).

Whether asbestos is ingested following inhalation,or as a result of asbestos present in food or water,the consequences can be regarded as to be ofnegligible health significance. In fact, the risk hasbeen classified as 'sensibly zero' (17, 18). High­dose animal feeding studies have shown negativeresults (16, 17, 19). Similarly, the humanepidemiological studies which have been conductedin areas where the levels of asbestos in water arehigh (due to the presence ofasbestos in rocks throughor over which the water flows) have also shownnegative results (9, 17, 18). Thus, the use ofasbestos-cement pipes to convey drinking water canbe regarded as having a clean bill ofhealth, as far asthe ingestion of asbestos fibres, which may bepresent in water, is concerned (9, 17, 18). WHO (in1989) and others on several occasions have re­confirmed that the use of asbestos-cement pipes forpotable water supply is generally appropriate (17,20).

In the case of asbestos fibres which may enter theupper respiratory tract and temporarily stay there(the larger fibres), these are not considered as sourcesfor asbestos-related diseases. The effect, if any,would be associated with those minute fibres whichdo exist in environmental air, some of which mayenter into the lung and be deposited in the depths of .the jung (1, 3, 16).

It is important to make a clear distinction betweenthe manifest health effects associated with veryheavy occupational exposures to asbestos, and thelack ofany demonstratable health effects associatedwith the general environmental levels of asbestos.In fact, the World Health Organization considers thatthe risk ofmesothelioma and lung cancer attributableto asbestos exposure in the general populations tobe undetectably low (1). Nevertheless, itis importantto try to estimate the extent of any possible health

13

risk. This has been carried out by various specialistsin recent years (3-10, 12-23). By very accuratecomparisons and extrapolations with the data relatedto the past heavy industrial exposures, and relatedhealth effects, it is now possible to obtain estimatesof the health risk for present-day environmentallevels ofasbestos, primarily, chrysotile asbestos (I­10). The evaluations carned out so far indicate that

. it is a seemingly trivial health risk (3-5, 7, 9).

The cancer risk, ifany, from being exposed to present­day levels of around 0.0005 fibres of more than 5microns long per m!. air, (longer term exposure) is atmost a 'rare-event and extremely low-level risk'. Thisrisk, for example; is perhaps equivalent to the risk ofbeing killed by lighting, or developing cancer fromeating frequently charcoal-broiled meat, or ofdeveloping cancer from the increased cosmic radiationby flying across the Atlantic, say, once a year (seeenclosed table). The estimated level oflifetime riskof cancer from being exposed to the typicalenvironmental level of asbestos of 0.0005 fibres perm!. air, greater than 5 microns long, appears to bearound one in 100,000 which is at a level whereinformed society would not consider further controlsto be warranted (3, 24, 25).

Such environmental risk estimates are calculatedfrom occupational data and involve the use ofa linearmodel for lung cancer, and a power model formesothelioma (6, 7). For a variety of reasons,including the fact that many past occupationalexposure figures underestimated the true exposuresituation for different types ofmixtures ofasbestos,the estimated risk values are on conservative side.The values are conservative also because the modelassumes that effects could occur even for extremelylow exposures meaning that the model neglects a'threshold' below which no effect would occur. Thetrue risk could well be much lower because thepublic's pres'ent-day exposure level, ispredominantly, to chrysotile asbestos which has amuch lower potential risk in comparison withamphibole types of asbestos (I, 3-10).

Even in tlle past, areas near chrysotile mining inCanada, where the airborne exposure for the generalcommunity was some 200-500 times that in urbanareas of North America (26), no significant healtheffects, including cancer, were detected which couldbe attributed to environmental asbestos exposure.A similar case was also reported for the asbestos

14

mining and processing towns of Austria (2, 3).Furthermore, there is now emerging evidence that athreshold exposure level to asbestos - below whichno known effects would arise (3) - is in existence.

ENVIRONMENTAL RISK INPERSPECTIVE

It is well known that some risks which people faceare relatively less important than some other risks.Even though relative risks are often not wellrecognized by many people, measured risks have been

. reported and documented for some years now. Thetable appearing at the end of this article provides anidea of the risk of being exposed to environmentalasbestos levels in comparison with other risks. It canbe observed that the estimated risk frombeing exposedto environmental asbestos is, at most, equal to or lessthan the very rare-event risks which people face (3).A level of lifetime risk of one in 100,000 estimatedfor current environmental levels ofasbestos exposureis such that if, for example, 20 per cent ofa populationof 50 million in a country experience a typicalenvironmental exposure to 0.0005 fibres per m!. for20 years, then the anticipated risk would be only onedeath per year (7).

CONTROL OF ASBESTOSEMISSIONS TO THEENVIRONMENT

As the risk of being exposed,·to the fibres releasedfrom present-day usage of asbestos products havebeen predicted to the extremely low, it seems thatthere should be no special need to curtail the use ofasbestos products or adjust control levels further.This is mainly, due to proper controls which arebeing exercised nowadays. If, however, in somecircumstances, adequate control measures are notbeing taken, then the adopted codes ofpractice andguidelines should be applied so as to maintain anacceptable low level of environmental risk.

Although overall control is very important, there arethree particular situations which, at present, requirespecial attention:

(a) Old asbestos products in buildings and itsremoval;

(b) Demolition of buildings in which substantialquantities of asbestos are present; and

,.

(c) Asbestos-waste disposal.

Note: particular attention needs to be given toamphibole asbestos (2-6, 8-11).

Since the occupational risk of exposure toamphibole-types of asbestos is relatively high(compared with chrysotile), these types ofasbestos,(primarily crocidolite and amosite) are encouragedto be phased out.

ASBESTOS CONTROL IN MININGAND MILLING

Special control measures have been developed andadopted for the asbestos mining and milling, becauseboth are potentially very polluting operations (27).Good control can usually be achieved in many miningactivities if adequate amount of water is provided.The processes of milling asbestos ore can also beaffectively controlled which will result in minimizingthe amount of fibre released into the generalenvironment. This can be achieved, for example,through the use ofelectrostatic precipitators, cyclonesand bag-house filter systems (2).

ASBESTOS CONTROL IN PRODUCTMANUFACTURING PROCESS

In the past, during some manufacturing processes,it was 'rather difficult to control the emissions offibres and to bring them down to an acceptable level.However, through the application of advancedtechnology, and the extensive use ofwet processes,it has become easy to control the release ofasbestosfibres to an acceptable level both for the protectionof workers as well as contamination of theenvironmental air and water (27). Variousregulations already exist in different countries which,limit direct emissions of asbestos into the generalatmosphere (2). Careful control has been introducedto ensure that workers take shower before leavingtheir workplace, as well to ensure that they do notgo home wearing contaminated clothing (2, 11, 12,14,15).

ASBESTOS CONTROL INCONSTRUCTION

Asbestos products used in construction are mainlycement-bound materials such as corrugated roof

sheets/tiles, pipes, panels, etc. In modem factories,the processes of manufacturing asbestos-basedmaterials are so that an adequate and firm bindingof asbestos fibres in cement matrix is ensured (12).In cases where the materials need to be cut/shapedon site, special and highly effective cutting tools,including those into which water is inj ected areavailable. Codes of practice relating to the use ofpresent-day asbestos products are readily availableand these should be followed by the personnelinvolved (2, 14, 15).

ASBESTOS CONTROL INBUILDINGS

In general, the risk from exposure to asbestos inbuildings has been predicted to be extremely low(4, 5, 11). In the past however, the use of asbestosin buildings createc\ some risk to occupants if theywould be exposed to substantial amounts ofasbestosfibres over some period oftime (3). This could havebeen because of serious deterioration or damage ofcertain types of asbestos materials, including thepresence of sprayed-on friable asbestos. In suchcases, either remedial measures such as sealing andencapsulation or removal may be considered to bewarranted (11). In the case of removal, there hasbeen many reported cases ofelevated environmentallevels which were created due to application ofinappropriate measures (3). It is, therefore, essentialto adhere to established control measures duringremoval. Many people are of the opinion that thecomplete removal of asbestos from buildings is, infact, unnecessary and unwise because:

(a) the removal workers may be ,needlesslysubjected to elevated levels of exposure;

,(b) owing to malpractice and accidents, significantamount of asbestos fibres could be releasedinto the environment; and

(c) apart from the high cost of removal and thesubsequent health risk, it would be perhapswiser to seal the damaged/friable asbestos sothat any release of fibre in the air would bearrested (3, 5).

ASBESTOS CONTROL IN BUILDINGDEMOLITION

If a substantial quantity of old asbestos, especially

15

amphibole asbestos is present in a building, then itmay be prudent to remove the material prior todemolition ofthe building. The procedures for doingthis are well-documented. It should be, however,borne in mind that most present-day asbestosproducts may create limited difficulties during thedemolition of buildings.

. ASBESTOS CONTROL IN WASTEDISPOSAL

Good control is important for handling, packaging,transportation, and disposal of asbestos waste tolandfill. The procedures for doing this are now well­documented. With proper control, which is usuallyeasily achievable, asbestos released to theenvironment would be minimal (15). With regardto industrial wastes containing asbestos, these areusually properly handled and controlled because, inmany situations, the material is wet. In addition,many industries are today recycling waste materialsas an economic and effective control measure. Withregard to asbestos emission control during handling,packaging, transportation and disposal, there arequite a number of regulations and guidelines inexistence in many countries (15).

CONCLUSIONS

The various sources and types ofasbestos which cancontribute to the exposure levels of asbestos inenvironmental ambient air, water, and soil, have beenevaluated. Particular consideration has been givento: natural asbestos sources, weathering ofasbestosproducts, asbestos release in the interior ofbuildings,the removal and disposal of asbestos waste, fibre­release from brake linings, and the re-entrainmentof deposited asbestos. It has been concluded that itis very important to follow control measures inmining, manufacturing and use of productscontaining asbestos.

Asbestos fibres which have less than 1.5 micronsthickness, and are larger than 5 microns are consideredto be of biological significance. 'In general, only asmall proportion of fibres in environmental ambientair is in this category. Much of the asbestos releasedto the air will not be inhalable because ofthe relativelylarge size of particles to which they are commonlyattached. This is especially true if the re-entrainedasbestos fibres are attached to general dust.

16

Nevertheless, there will be some fine particlescontaining asbestos which can enter the respiratorytract. Very fine fibres will get into the deep recessesof the pulmonary regions of the lung. Some inhaledparticles, deposited initially in the upper airways, mayultimately be swallowed and enter into the stomachand the gastro-intestinal tract.

Much of the asbestos contained in asbestos cementor in various modern products, is in a form wherethe fibres are essentially 'locked-in'. Some asbestoswill however, become degraded naturally in thepresence of water. At very high temperaturesassociated with friction, for example in car brakelinings, most ofthe asbestos is changed to innocuousand amorphous material.

The fine asbestos fibres which are released to theair, get often attached to solid surfaces and orincorporated in general dusts. This increases theeffective particle size ofthe original asbestos fibres,rendering them, in many cases, non-inhalable.Particles released to the air do not continue toaccumulate or remain suspended. They areeventually washed out by rain and conveyed torivers, sewers, and finally to the sea.

Most of the asbestos in environmental air is of thechrysotile form, with relatively few amphibolefibres. Amosite and crocidolite are, however alsopresent. Tpe World Health Organization hasconfirmed that chrysotile asbestos is far lesspotentially dangerous in comparison with amphiboleasbestos. Ofthe different sources ofenvironmentalasbestos investigated, there seems to be only alimited number of situations where a potentiallyundesirable health risk may exist. These includerisks to unprotected maintenance workers, and tothe people in the vicinity ofdeteriorating and friableasbestos.

Risks are also associated with inadequatelycontrolled asbestos removal practices, or for thosenear the uncontrolled asbestos waste disposalactivities. None of these situations need to be asignificant hazard ifthe established practices ofgoodcontrol are observed. Considerable data on the levelsof asbestos, types and sizes in environmental air arenow in existence. The present-day, long-termexposure level, primarily to chrysotile, is typicallyonly around 0.0005 fibres greater than 5 micronslong per mi. air. This itself supports the contention

that there is a very low-level of fibre release fromall combined sources.

It is possible to assess the maximum possible healthrisk of such very low levels of asbestos in theenvironmental ambient air. This can be done byextrapolation from the much higher occupationallevels and associated health risks. Further, it ispossible to compare these estimated risks withepidemiological data from industrial towns inCanada and Austria where the levels in the ambientair were relatively high for many years, and whereno health effects have been observed.

The health risk of cancer from exposure to present­day levels of asbestos in environmental air appearsto be trivial. The cancer risk, ifany, would seem tobe at most a 'rare-event, extremely low level risk'which, for example, is perhaps equivalent to the riskof being killed by lightning or of cancer fromincreased cosmic radiation exposure from atransatlantic flight once per year. The lifetime riskof cancer has been estimated to be at most, onlyaround one in 100,000. This is a level at whichinformed society would not consider further controlsto be warranted, and thereby it can be regarded asacceptable.

Some asbestos will be ingestedfollowing inhalation.Some will be swallowed when asbestos fibres ordusts containing it enter the mouth. In addition,some asbestos will be ingested from food, fromnatural sources or form the use of water flowing inasbestos-cement pipes. Following very intensiveresearch, no health effects from ingested asbestoshave been demonstrated. It is now widelyrecognized that ingested asbestos is ofno real healthconcern, it is a sensibly zero risk. The Warld HealthOrganization supports the continuing appropriate use.of asbestos-cement pipes to supply potable water.

Finally, taking into account all available data, therewould appear to be no scientific justification far thebanning, or the reduction in manufacture and use ofpresent-day asbestos products. This conclusionapplies equally to both developed and developingcountries. Nevertheless, continuing good overailcontrol, including that generally applied in mining,milling, manufacturing, use and asbestos wastedisposal, is required. Existing guidelines, rules andcodes must, therefore, be strictly adhered to.

REFERENCES1. World Health Organization: Asbestos and

Other Natural Mineral Fibres. . Geneva:World Health Organization, 1986.

2. Organization for Economic Cooperation andDevelopment: Control of Toxic Substancesin the Atmosphere; Asbestos. Monograph No.20. Paris: Organization for EconomicCooperation and Development, 1989.

3. Commins, B. T.: The Significance ofAsbestosand Other Mineral Fibres in EnvironmentalAmbient Air. Maidenhead, UK: ComminsAssociates, 1990.

4. Harvard University, Energy andEnvironmental Policy Centre: Proceedings ofSymposium on Health Aspects ofExposure to

. Asbestos in Building. Harvard, USA: John F.Kennedy School ofGovernment, 1989.

5. World Health Organization: Non­Occupational Exposure to Mineral Fibres.IARC Scientific Publications No. 90. Lyon,France: International Agency for Research onCancer, 1989.

6. National Research Council: Asbestos formFibres; Non-Occupational Health Risks,Washington: National Academy Press, 1985.

7. Doll, R., and J. Peto: Asbestos; Effects onHealth of Exposure to Asbestos. UK: HerMajesty's Stationery Office, 1985.

8. Ontario Ministry ofAttorney General: Reportofthe Royal Commission ofMatters ofHealthand Safety Arisingfrom the Use ofAsbestosin Ontario: Ontario Government Bookstore,Toronto, 1984.

9. . Dunnigan, J., and N. Seymoar: A ScientificUpdate on Asbestos and Health. Montreal:·The Asbestos Institute, 1988.

10. Commins, B. T.: Fate and Significance ofEnvironmental Asbestos. Paper presented atILO Safety and Occupational health Seminaron Mineral Dust in the Workplace, Istanbul,October 1988.

17

11. World Health Organization: Report of anInternational Programme on Chemical SafetyWorking Group Meeting on the Reduction ofAsbestos in the Environment, Rome,December 1988. Geneva, World HealthOrganization 1989.

12. Stack, T. N.,: Industry's Views on the Needsand Feasibility of Environmental AsbestosReduction. WHO Meeting, Eduction ofAsbestos in the Environment, Rome,December 1988.

13. Russell, A.,: Asbestos-Cement Markets: FullofEastern Promise. Industrial Minerals No.278, 39-57; 1990.

14. Asbestos International Association: AsbestosWaste Materials. Paris, France: Asbestos·International Association, 1988.

15.. Institute of Waste Management: Code ofPractice for the Disposal ofAsbestos Waste.Northampton, UK: Institute of WastesManagement, 1988.

16. National Institute of Public Health andEnvironmental Protection: Integrated CriteriaDocument; Asbestos. Bilthoven: TheNetherlands: National Institute of PublicHealth, 1989.

17. Commins, B. T.,: Asbestos Fibres in DrinkingWater. Maidenhead, UK: ComminsAssociates, 1988.

18. Commins,B. T.,: The Significance ofAsbestosin Drinking Water and the Use ofAsbestos­Cement Pipes. Pipes and PipelinesInternational. 33:7-14, 1988:

18

19. Summary Workshop on Ingested Asbestos:Environmental Health Perspectives 53:1-204,1983.

20. World Health Organization: Asbestos inDrinking Water. Dr. R. Helmer, World HealthOrganization, Geneva,S April 1989 (letter).

21. World Health Organization: Ail' QualityGuidelinesfor Europe. Copenhagen: WHORegional Publications, 1987.

22. Mossman, B. T., and J. B. 1. Gee: Asbestos­related Diseases. New England Journal ofMedicine, 320:1721-8,1989.

23. Davis, J. M. G., and S. W. Coniam: Low LevelExposure to Asbestos; Is there a Cancel' Risk?Brit. J. Ind. Med. 45:505-508, 1988.

24. Commins, B. T.,: Estimations of Risk fromEnvironmentalAsbestos in Perspective. Non­Occupational Exposure to Mineral Fibres.Lyon, France: International Agency forResearch on Cancer, 1989.

25. The Royal Society: RiskAssessment; A StudyGroup Report. London, UK: The RoyalSociety, 1983.

26. Churg, A.: Lung Asbestos Content in Long­term Residents ofa Chrysotile Mining Town.Amer. Rev. Respiratory Diseases. 134: 125­127, 1986.

27. Bragg, GM.,: The Basics ofAsbestos DustControl. Montreal, Canada: The AsbestosInstitute, 1988.

TABLE: LIFETIME RISK VALVES FOR SELECTED SITUATIONS

Selected risk situations. Mainly United States data

Lifetime risk per 100,000

Extra High Risk

Smoking (all causes of death) ; 21,000Smoking (cancer only) :...................... 8,800

High Risk

Motor vehicle 1,600

Elevated Risk

Frequent airline passenger (deaths) 730Cirrhosis of liver, moderate drinker (deaths) ; 290Motor accidents, pedestrians (deaths) 290

Moderate Risk

Light drinker, one beer per day (cancer) 150Drowning deaths; all recreational causes 140Air pollution, United States, benzo (a) pyrene (cancer) ; 110Natural background radiation, sea level (cancer) 110Frequent airline passenger, cosmic rays (cancer) 110

Low Risk

Home accidents (deaths) 88Person sharing room with smoker (cancer) 75Diagnostic X-rays, (cancer) 75(Risk level where few would commit their own resourcesto reducerisk; Royal Society, London) 70

Very Low Risk

Living in brick building, natural radiation (cancer) 35Vaccination for small pox, per occasion (death) 22One transcontinental air flight per year (death) 22Saccharin, average United States consumption (cancer) 15Consuming Miami or New Orleans drinking water (cancer) 7(Risk level where few would consider action necessary,unless clear causal links with consumer products,Royal Society, (London) 7

19

Extremely Low 'Rare-Event' Risl,

One transcontinental flight per year, natural radiation (cancer) 4Radiation (cancer) 3Lightning (deaths) 3Hurricane (deaths) 3Charcoal broiled steak; one per week (cancer) 3

. ENVIRONMENTAL ASBESTOS RISK (cancer),(around one per 100,000 or lower) - 1('Acceptable' risk, WHO, drinking water (cancer) 1(Further control not justified, Royal Society, UK) 0.7

20

HEALTH AND SAFETY IN·CONSTRUCTIaN***

A. INTRODUCTION

Construction industry is a very resource-demandingand labour-intensive industry. It requires enormousamount of natural and processed products andchemicals, the inappropriate and unsafe use ofwhichmay have negative impact on the environment andmay be hazardous to the health ofworkers. In manycountries, special guidelines and regulations relatedto health aspects of certain building materials, andhow they can be safely used on construction sites, arealready in existence. However, because of variousreasons (mainly because of lack of awareness,particularly in many developing countries), manyworkers do not fully follow these regulations andconsequently they are exposed to health risks.

Similarly, safety of the workers in constructionoperations is an important issue which requires greatattention. Accidents occurfrequently almost in everyconstruction site, small or large. Adhering to theestablished guidelines and procedures in order toprevent the occurrences of accidents, and tosafeguard the health of workers, are as important asthe technological or managerial requirements ofevery construction site.

The purpose of tllis article is to briefly, outlinepotential healtll hazards associated with the unsafeuse ofcertain materials in construction and measuresto prevent such hazards. The paper also describessome important measures for ensuring safety ofworkers during construction operations.

B. HAZARDOUS MATERIALS

Chemicals

Chemicals are extensively used in construction.There is hardly any construction site in which

••• This article has been edited by Baris Der-Petrossian,Research and Development Division of UNCHS (Habitat). Itis based on sections 11, 12, and 13 of!he International LabourOffice (ILO's) publication entitled: Safety, health and welfareon construction sites - A training manual, ISBN 92-2-1 09182­1, (Jeneva, 1995. The kind permission of ILO in using !hepublication for the preparation of this article is thankfullyacknowledged.

chemicals are not present. Chemicals are foundmainly in:

o Adhesives

o Cleaning agents for brickwork and stonework

o Decoration/protection treahnents for timberand metals

o Floor treahnent

o Pesticides and fungicides

o Insulation materials

o . Solvents, etc..

Among all above mentioned chemicals the mostimportant and widely used ones are solvents,lacquers, varnishes, paints, thinners and similarcleaning materials.

Many chemicals are hazardous, with a potential forfire and explosion, or toxic with an inherent potentialto cause poisoning. In view ofthe importance andgreat benefits chemicals provide in construction, itis advisable to place the health risks associated withthe use of chemicals in an appropriate perspective.

Toxic chemicals cause both acute effects, such asdizziness, vomiting and headaches, produced in ashort time by exposure to solvents, and chronic effectsresulting from exposure over a long period as in lungdiseases such as asbestosis and silicosis. Contactdermatitis may result from the contact between tlleskin and some chemicals. Acids and alkalis are

.corrosive and can damage both skin and eyes.

Elltry illto the body

Chemicalscan enter the body by various means andways. The main risk to health is, often, associatedwith indoor applications of chemicals and arisesfrom evaporation ofsolvents into the breathing spaceof tlle workers or building occupants. Other risksinclude contact by tl1e coating witl1 tl1e skin or eyes.Depending upon whether a chemical is solid orliquid, or in form of airborne dust, vapour fumes orgas, a chemical can affect the health in various ways.The main routes into the body are (figure 1) by:

21

Inhalation (breathing in) Ingestion (swallowing) Absorption (skin contact)

Figure 1. Chemicals enter the body by inhalation, ingestion and absorption

o Inhalation or breathing in

This is the most important route of entry.Some toxic gases and vapours cause irritationin the nose and throat and so give warning oftheir presence. Others do not, and penetrateto the lungs or blood stream easily. Airborneparticles which are not visible reach deep intothe lungs. Inhaled particles accumulate in thelungs, producing changes and causing anincurable disease called "pneumoconiosis".Breathlessness and inability to work are theeventual consequence.

o Ingestion or swallowing

This is possible when chemicals such as lead­based paints are handled carelessly. Eatingor smoking without first washjng hands, whentoxic vapours have contaminated cups, platesor eating utensils, or when meals are eaten atthe work site. These are avenues of entry ofchemicals into the body.

o Absorption through the skin

Some solvents can be absorbed through theskin into the blood stream and may travel tointernal organs such as the brain and liver.

Contact dermatitis or eczema frequently result fromthe. contact between the skin and some chemicals.Acids and alkalis are corrosive and can damage theskin and the eyes on contact. Unless large amountsof water are used at once to rinse the substance off,serious bums will be caused.

22

Preventive measures

Health hazards associated with the use ofchemicalscan be prevented ifworkers and users are aware ofthe health implications and risks resulting from theuse of chemicals. It is essential that users ofchemicals follow the established safe practices inhandling these materials.

Generally, there is an order of priority in themeasures for dealing with hazardous chemicals:

o Substitute the chemical with a hafmless or lesshazardous one,

o Enclose the process using the chemical, orprovide other engineering controls such asexhaust ventilation; this is often difficult inconstruction processes,

o Use personal protective equipment (PPE).

If the use of hazardous chemicals cannot beavoided, the following basic safety measuresare ·recommended so as to reduce/preventhealth hazards:

o Keep containers ofchemicals in a separate andsecure store.

o Iftwo containers look the same, do not assumethat they contain the same material.

o Make sure there is a label on the container(figure 2) - ifthere is no label, then do not usethe contents

I

\'Ii

Ir:

as_-I ..-.__

--11.O-CI5 Ql.121l 1l£IlEVAn

.,'- ..,="""'..,'_".""LlIC1'._..."'-.,..CHEMICAL INFO-SHEET

UIIUllr

~.,......- ",

~~=.:7 .,., .... ....,........,.~-::..-===.

Figure 2. Every chemical used on site should have alabel and slif.ficient information to ensure its safe use

o Read the label and make sure you understandwhat it says, then follow the instructions.

o If the information is not sufficient to tell youhow to handle the chemical safely, ask yoursupervisor for the chemical safety data sheet(figure 3) and do not use the chemical untilyou have seen it. Ifyou do not understand it,ask questions until you do.

o Check that you are wearing the correct PPEbefore you handle chemicals (the chemicalsafety data sheet should say whether you needgloves, eye protection, protective clothing,rubber boots or respirators) and that the PPEis in good order.

o When opening containers, hold a rag over thecap or lid as some volatile liquids tend to spurtup when this is released. Transfer the contentsof containers in the open air.

o Avoid breathing in any fumes from chemicals.Provide good ventilation, or work in the openair. Leave the work area immediately if youfeel dizzy or unwell.

Figure 3. An example ofa chemical safety datasheet, providing essential safety and healthinformation

o If you are using large quantities of solventswear impermeable clothing. Remove anyclothing wetted by solvents and leave it to dryin a well-ventilated place.

o Use the smallest quantity of chemicals that isnecessary for the particular job.

o Eye protection should be worn when chemicalsare being moved or transferred on site.

o When mixing or pouring chemicals usingtemporary containers, make sure they aresuitable and.correctly labelled. Never use foodor drink containers.

o . Wash before you eat and do not eat or smokeat your workstation.

o If the skin is splashed with a chemical, itshould be rinsed immediately with plenty ofclean running water. Eyes should be flushedout thoroughly with water and should receiveimmediate medical attention.

o Ifyou are burned by a chemical, or feel unwellafter using a chemical, seek medical attentionWitllOut delay.

23

a Ifthere is a spillage ofchemicals on the groundor floor, report the matter at once so that theright action can be taken, such as soaking upwith dry sand (figure 4.)

Hig/zly flammable chemicals

Many chemical substances used in construction arehighly flammable as well as toxic. The following

. precautions should be followed when handling orusing them:

a Study the label and the instructions on thechemical safety data sheet about safe handlingand first-aid measures.

,a Remember that all flammable liquids produce

vapours which are invisible and are easilyignited. Never smoke if there are flammablechemicals in the area. Find out what action totake in the case of fire.

a Keep containers in the store until required foruse, and return them there when you havefinished with them. Store drums upright.

a .Treat empty drums with as much care as fullones - they will still contain flammable vapour.

a Always transfer the contents of largecontainers to small containers in the open air.

a Use funnels and spouts to prevent spillage.Soak up any spillage with dry sand and removethe contaminated sand to a safe place in theopen air.

a If you cannot avoid using highly flammableliquids in an enclosed area, make sure there isan adequate supply of fresh air. . This canusually be achieved by opening windows anddoors to the full. If it is necessary to use a fan,check that the fan is electrically safe to use ina flammable atmosphere.

Portland cement

Portland cement is a class ofhydraulic cement whichhas two essential constituents: tricalcium silicate anddicalcium silicote. It has also varying amount ofalumina, tricalcium aluminate and iron oxide.Cement mixes are a well-known cause of skindisease. Both irritant and allergic contact dermatitiscan result from proximity to wet cement. Cementdermatitis is usually due to primary irritation fromthe alkaline, hygroscopic and aggressive properties

24

of cement. Prolonged exposure to wet cement maycause cement bums or ulceration of the skin. Thefollowing precautions should be taken:

a Avoid breathing in cement dust, as well as indust created by the surface treatment ofhardened concrete which may contain a highsilica content, by wearing suitable respiratoryprotective equipment.

a Protect the skin from contract by wearinglong-sleeved clothing and full-length trousers,with rubber boots and gloves when required.

a Protect the eyes; if any cement gets into theeyes, rinse them immediately with plenty ofwarm water.

a Immediately wash off any dust or freshlymixed cement that gets on to the skin.

a Clean offyour clothing and boots after work.

Asbestos

The commercial production of asbestos is mainly inthree types namely: (a) crocidolite (blue), (b)amosite (brown), and (c) chrysotile (white).Asbestos fibres are strong and highly resistant toheat and chemical attack. They are, therefore,excellent ingredients for many industrial andconstruction products. Airborne asbestos fibres, ifinhaled in large quantities and over a long period oftime are dangerous to human health. The principaldiseases known to be caused by exposure to asbestosare asbestosis (fibrosis or scarring ofthe lung), lungcancer and mesothelioma (a cancer of the innerlining of the chest or of the abdominal wall).

Situations in which one can be exposed to asbestosfibres could be summarized as follows:

(aJ asbestos insulation or coating usedfor:

(i) thermal insulation of boilers;(ii) fire protection of structural steelwork;(iii) thermal and acoustic insulation of

buildings;(iv) brake-pad lining in cars;

(b) asbestos board used in construction such as:

(i) fire protection on doors, protected exits,etc;

(ii) cladding on walls, ceilings, etc;(iii) internal walls and partitions;

-

Figllre 4. Chemical spillage soaked lip with dly sand

I CHEMICALS!! STOR E

25

(iv) ceiling tiles in a suspended ceiling;

(c) asbestos cement, which is found in:

(i) corrugated sheets (roofing and claddingand door facings);

(ii) flat sheeting for partitioning, cladding;(iii) gutters and downpipes; and(iv) water pipes.

Before starting any work with asbestos, an adequateassessment must be made to work out the precautionsneeded to control the fibre emissions. Work withasbestos may range from mining, milling,production, use, removal and waste disposal.

,In many countries those who work with asbestos andin particular in mining, milling, removing anddisposing of asbestos, require to be licensed or tohold a permit. In working with asbestos, andasbestos products, workers need to wear suitableprotective clothing. Only working methods that keepasbestos dust levels as low as possible should beused. Asbestos cement is less likely to generate dustthan many other asbestos products, but the risk of

asbestos dust release is still present. Where it is notpossible to keep asbestos dust levels under controllimits, respirators should be worn by workers.

Methods of limiting exposure to asbestos dustinclude:

o Be aware of materials likely to containasbestos;

o Remove asbestos materials before startingmajor demolition work. This preventsaccidental exposure to asbestos;

o Use wet methods of removal (to suppressdust);

o Prompt removal and bagging of wasteasbestos, and dispose at an approved wastedisposal site;

o Separate asbestos work areas from othergeneral work areas;

o Wash or take shower at the end ofthe workingday;

o Do not take working clothes home.

Lead

Lead is perhaps the most critical construction

26

material with health implications. Inorganic lead isfound in many construction products, e.g. electricitycables, pipes, gutters and old lead sheet roofs.Organic lead is added to motor fuels, and storagetanks will be heavily contaminated.

There is a risk to health from inhaling dust or fumescreated by burning or cutting materials containinglead, including painted surfaces, by welding, bygrinding or cutting, and by spray painting of leadedpaints. Lead can be absorhed when swallowed,usually when food is contaminated. Organic leadcompounds are readily absorbed through the skin.

Excessive lead absorption causes constipation,abdominal pain, anaemia, weak muscles and kidney

.damage. It can also affect the brain, causingimpaired intellect, strange behaviour, fits and coma.While working with lead in any form, the followingprecautions should be taken:

o Do not use lead-based paints, particularlywhen it is accessible to children.

o Wash yourhands regularly, and always beforeeating; the risk is higher if you smoke withlead on your hands.

o Use protective clothing and respiratoryprotective equipment which should beprovided whenever lead levels exceed nationalcontrol limits.

o Wear work clothing on the job and store youroutdoor clothing where it cannot becontaminated by your work clothing.

o While removing the old paint work containinglead-base paint, it is better to use chemicalstrippers rather than mechanical methods.

Wood preservatives

Wood used in construction, is often, .attacked by. . .

insects such as termites and certain beetles and whenexposed to humidity it will be exposed to fungaldecay. when risks of rot or insect attack are high,the use of durable timber is recomended (ifeconomically feasible). Otherwise timber used inconstruction has to be preserved/treated for ensuringdurability.

Wood preservatives are in general toxic and harmfulto human health. Use of wood preservatives,therefore, requires an understanding of potential

•

health hazards and safe working procedures.

The health hazards associated with the use ofwoodpreservatives include: skin irritation, eyeinflamation and lung desease ifinhaled. When usingwood preservatives following precautions may needto be followed:

o Use protective clothing and gloves when usingpreservatives;

o Provide protection equipment to workers toprevent inhalation ofpreservatives particularlywhen spraying methods are applied;

o Create good ventilation when using woodpreserative in closed areas such as in atics ofroofs.

o Do not eat, ddnk or smoke while being'busywith applying preservatives. Ingestion ofevensmaIl amounts of wood preservatives couldbe deadly dangerous.

o Dispose the empty preservative containers.Reusing them might generate health risks suchas for keeping water or food in the oldcontainers.

c. OTHER HAZARDS

Noise atld vibratiotl

Construction sites are noisy places. Excessiveexposure to loud noise can cause permanent damageto hearing of workers. Noise at work can causestress, making it difficult to relax and sleep. Veryhigh levels of noise caused, for example, by usingcartridge tools can cause instantaneous hearingdamage.

The levels of noise produced in operations such as 'drilling, piling, tunnelling, steel work and cleaningoperations may be such that unprotected persons willexceed their maximum recommended daily dose ina matter of seconds. Even a few minutes' exposureevery day to very noisy machines can be enough tostart permanent hearing damage. Loud noise cancause a temporary partial loss of hearing, withrecovery time varying from 15 minutes to severaldays depending on the noise level. There may alsobe a :'ringing" in the ears which should be regardedas a warning - temporary loss may becomepermanent with repeated exposure. Deafness

develops very gradually but cannot be cured oncethe damage has been done.

Noise also makes it difficult to hear sounds that youneed to hear such as work signals and warningshouts.

There are several steps that can be taken on site toreduce noise:

o Check that exhaust outlets are fitted withsilencers or mufflers, and do not keepmachinery running unnecessarily.

o Keep compressor motor covers closed whenthey are running (figure 5).

o Check that concrete breaker mufflers andsimilar devices are securely fitted (figure 5).

o Check that machinery panels are secured and, do not rattle.

o Ensure that sound-insulating screens areprovided to reduce noise from stationary plant,and that where practicable, noisy machineryis sited behind earth mounds or brick stacksto isolate or screen it as far as possible.

Hearitlg protectiotl

If work is done at or neara noisy machine thefollowing hearing protection measurers may betaken:

o Ask if noise levels have been measured, andwhat those measurements are.

o Remember that noise which is continuous ata level of 85-90 decibels (dB(A)) or more isinjurious to hearing.

,0 Ask for appropriate earmuffs or ear plugs ifyou work with or near a noi~y machine andmake sure they fit properly and arecomfortable (figure 5).' .

o Keep your hearing protection clean and in asafeplace when you are not using it.

o Insert ear plugs with clean hands.I

o Look out for damage: ifthe earmuffs no longerfit properly or the seaIs have become hard ordamaged, ask for replacement.

It is not true that ear protectors make it more difficult

27

Figure 5. Compressor noise control - keep covers closed, use muffler on pneumatic hammer and wear hearingprotectors. Wear them all the time while working in a noisypart ofthe site

28

to understand speech or hear warning signals, as theyreduce both unwanted noise and alarm signalsequally; the signal can actually be heard more easily.

Note: Ifyou have to shout to make yourselfheardby someone about one metre away, this is a noiseproblem requiring action.

In addition to noise generated by many constructionequipment, many ofthe machines or hand-operatedtools transmit vibrations to the body - pneumaticrock drills or concrete breakers are commonexamples. In this way they can injure muscles andjoints, and affect blood circulation causing what isknown as "white fmger disease". When using thesetools, workers should wear gloves, which help tocushion the vibrations and work with certainintervals in order to give the muscles andjoints sometime to relax.

Liglztillg

All parts ofthe site need to be properly lit by naturalor artificial means whenever work is going on. Sitelighting is always necessary in those areas short ofnatural light such as shafts and enclosed stairways.Artificial lighting should be placed to avoid deepshadows - these may conceal hazards which wouldbe obvious in good light. Mounting oflights shouldbe as high as practicable to avoid glare, and lightsshouldbe placed so that workers do not have to workin their own shadow.

Only robustly installed fittings which are well outof reach, such as floodlighting, should be at fullmains voltage. Temporary electric lighting shouldbe installed by trained electricians using low-voltageequipment. The safe use oflighting can be achievedby the following ways:

o Do not interfere with the installation.

o Report any damaged insulation, or brokenbulbs, lampholders or fittings.

o Make sure that cables are fastened well offthe ground securely and do not let cables orconnections trail in wet conditions.

Exposure to heat alld cold

Hot weather

Workers on construction sites are often exposed to·all types ofweathers. In tropical countries radiation

from the sun, with high air temperatures andhumfdity, increases fatigne from heavy work andcauses heat stress which may lead to heat exhaustionand heatstroke, the latter a medical emergency, andto ill health. The effects of heat combined withphysical workload tend to accumulate.

Good welfare facilities are essential to health in hotclimates, and the suitable arrangement of workingtime is important. There should be: .

o sufficient work breaks: for moderately heavyor heavy work, 50 per cent or more rest timeis essential;

o rest areas away from workstations to cool off;

o an adequate supply to clean, cool drinking­water: drink often and in small quantities;

o washing facilities to keep work clothes clean.

In order to keep cool in hot climates, it is helpful toknow and exercise the following:

o Keep out of direct sunshine as much aspossible.

o Avoid unnecessary quick movements.

o Ensure that there is air circulation in operator'scabin.

o Avoid wearing tight clothes or those whichprevent evaporation of perspiration such assome plastic materials.

o Wear head protection.

o Take cool drinks regularly to replace moisturelost through perspiration.

o Add salt to food or eat food that containsnatural salt.

o . Find a shady place for rest pauses.

Cold weather

Cold is not just uncomfortable - it may affect healthand judgement. Although not a serious problem intropical climates, it may nevertheless be experiencedat high altitudes and in the early morning at siteswhich" are well inland.

Some ofthe hazards of cold weather are as follows:

o There is great likelihood to be exposed to

29

II

iii

iI,

I

accidents if the temperature of the hands fallbelow 15° Celsius: there is loss ofconcentration and coordination.

o Workers repeatedly using vibratory tools suchas rock drills may suffer "white fingersyndrome involving sensory loss as aconsequence of cold.

o Prolonged exposure to temperatures aroundfreezing may cause frostbite or hypothermia.

o Wind can affect temperature. When the airtemperature is 10° Celsius and the wind speedis 32 km per hour, the temperature, so far asthe body is'concerned, fall to freezing. This iscalled the chill factor.

o Even where the temperature is above freezingpoint, a condition called "immersion foot" canoccur in wet conditions if the feet are not keptdry.

The following points should be considered whenworking in cold conditions:

O· Choose clothing which allows moisture toescape but does not allow wihd and rain topenetrate: waterproofclothing tends to preventevaporation of moisture.

o Avoid bulky clothes, as they hampermovement - a number of layers clothing arepreferred.

o Hands and feet are particularly susceptible tocold.

o Use facilities for preparing hot meals anddrinks, and for storing and drying clothing.

D. PERSONAL PROTECTIVEEQUIPMENT (PPE)

Why is PPE Ileeded?

The working conditions in construction are in most·cases such that, despite all preventive measures inproject planning and work design, some personalprotective equipment (PPE), such as a helmet,hearing and eye protection, boots and gloves, isneeded to protect workers. However, there aredisadvantages in using PPE:

o Wearing some forms of PPE may involve

30

discomfort to the user and slow down thework.

o Extra supervision is called for to see the PPEis worn.

o PPE costs money.

Wherever possible, it is better to try to eliminate thehazard rather than providing PPE to guard against it.

Some PPE such as safety" helmets and footwearshould be used on all construction sites. The needfor other PPE will depend on the sort of work. Itshould also be borne in mind that proper workclothes will provide protection for the skin.

Head protectioll

Falling objects, overhead loads and sharp projectionsare to be found everywhere on construction sites. Asmall tool or bolt falling from 10 or 20 m high cancause serious injuries or even death if it strikes anunprotected head. Head injuries often occur whenmoving and working in a bent position, or whenarising from such a position.

Safety helmets protect the head effectively againstmost ofthese hazards, and one should wear a helmetwhenever being on site and particularly in locationswhere overhead work is going on. These areas,known as "hard-hat areas", should be clearly markedwith safety signs at entrances and other suitableplaces (figure 6). The same rule applies to managers,supervisors and visitors. qnly safety helmets whichhave been tested to national or internationalstandards should be used. A chin-strap on the helmetprevents it from falling offand should be used whenappropriate.

Halld alld skill protectioll

Hands are extremely vulnerable to accidental injury,and in construction more injuries are caused to handsand wrists than to any other part of the body. Openwounds, abrasions, fractures, dislocations, strains,amputations and .burns occur. They are largelypreventable by better manual handling techniquesand equipment, and by wearing suitable handprotection such as protective gloves and gauntlets.

Among the common hazardous tasks where handprotection should be provided are:

o operations involving contact with rough, sharp

,Figure 6. "Hard-hat" areas - all or mostparts ofconstruction sites should be marked by signs as"hard-hat" areas

31

or jagged surfaces;

o contact with or splashes from hot, corrosiveor toxic substances such as bitumen and resins;

o working with vibratory machines such aspneumatic drills where some cushioning ofthevibrations is desirable;

o electrical work in humid and cold weather.

Skin trouble is common in the construction industry.Contact dermatitis is the most common type of skindisease. It feels itchy and looks red, scaly andcracked, and can become so bad that it effects yourability to continue working. Wet cement is one ofthe main skin hazards, but other substances includetar and pitch, which can cause skin cancer afterprolonged exposure as well as paint thinners, acidsfor masonary cleaning and epoxy resins. In additionto gloves, it is strongly recommended that workersuse barrier creams and wear long-sleeved shirts, full­length trousers and rubber boots.

Foot protection

Foot injuries fall into two broad types: those due topenetration ofthe sole by nails which have not beenknocked down or removed, and those due to crushingby falling materials, which can be minimized bywearing protective footwear. The type of safetyshoes or boots to be used will depend on the natureof the work (e.g. the presence of ground water onconstruction sites), but safety footwear should havean impenetrable sole and uppers with a steel toe­cap.

There are many types of safety footwear nowavailable such as:

o light, low-cut leather safety shoes for climbingjobs;

o normal safety shoes or boots for heavy-dutywork;

o rubber or plastic safety wellingtons orgumboots which provide protection againstcorrosive substancys, chemicals and water.

Eye protection

In construction industry many eye injuries occur asa result of flying material, dust or radiation whenthe following jobs are being carried out:

32

Figure 7. Eye protection must be suitable,comfortable and available to encourage workers towear it

o breaking, cutting, drilling, dressing or layingof stone, concrete and brickwork with handor power tools;

o chipping and dressing painted or corrodedsurfaces;

o cutting offor cutting out cold rivets and bolts;

o dry grinding of surfaces With power grinders;

o welding and cutting of metals.

In some industrial processes there may also be a riskfrom the spillage, leakage or splashing of hot orcorrosive liquids.

Some ofthese hazards can be removed permanentlyby proper machine guarding, exhaust ventilation orwork design. For many hazards, for example, stonecutting or dressing, personal eye protection (goggles,safety glasses or shields) fs the only practicalsolution. Sometimes workers are aware of thedanger they run and the consequences if their eyesare damaged, but do not wear eye protection. Thisis because the type chosen interferes with vision oris uncomfortable to wear, or is not immediately athand when needed (figure 7).

Respiratory protection

On construction sites there are often tasks whereharmful dust, mist or gas may be present, such as:

1. Prefilter 2. Dust filter

-.

1. .....: 2.

Gas filter

Combination filter

Figure 8. Three types ofholf-faced mask wi/17ft/tel's

33

o rock crushing and handling;

o sandblasting;

o demolishing buildings containing asliestos orasbestos-based materials;

o welding or cutting materials with coatingscontaining zinc, lead, nickel or cadmium;

o paint spraying;

o blasting.

Correct choice ofrespirator

Whenever there is doubt about the presence oftoxicsubstances in the atmosphere, a respirator must beworn. The correct type of respirator will dependupon the hazard .and the work conditions, and oneneeds to be trained in its use, cleaning andmaintenance. Advice on suitable types ofrespiratorand filter should be sought from appropriate safetyand health authorities.

The simplest masks are disposable paper types.Remember that these are only effective againstnuisance dusts.

These are three types of half-face mask with fIlters(figure 8).

o for protection against airborne particles, e.g.stone dust, with a coarse filter fitted in thecartridge (note, these filters have a specificlifetime and should be changed as necessary);

o for protection against gases and fumes, e.g.when using paints containing solvents, with afilter containing activate car~on;

o a combination filter containing both a dust anda gas filter. Cartridges must be replacedregularly.

A full-face mask can be fitted with the same typesof filter, and it also protects the eyes and face.

Self-contained breathing apparatus with full-facemask fed with air at positive pressure always givesthe best protection, and must be used in confinedspaces and whenever a sufficient supply of air oroxygen at the working place is in doubt. The airmay be supplied from a compressor with a filter, orair/oxygen bottles (figure 9). In a hot climate, thefull-face type is the m~st comfortable mask because

34

it is looser fitting around the face and the air itselfhas a cooling effect. Users must be trained in theuse of self-contained breathing apparatus and mustkeep to the manufacturers' specifications.

Safety hamess

The majority of fatal accidents in construction aredue to falls from heights. Where work cannot becarried out from a scaffold or ladder, or from amobile access platform, the wearing ofsafety harnessmay be the only way to prevent serious injury ordeath.

One of the common situations in which a safetyharnesses may be used - sometimes supplementedby use ofa safety net - is maintenance work on steelstructures such as bridges and pylons. .

There are many types of safety belt and safetyharness available. The manufacturer or suppliershould be asked for advice on suitable types for theintended purpose and for instructions on use andmaintenance. A full safety harness should alwaysbe used in preference to a safety belt.

A safety harness and its lanyard must:

o limit your fall to a drop ofnot more than 2 m.by means of an inertia device;

o be strong enough to support your weight;

o be attached to a strong structure through a firmanchorage point above the place at which youare working.

E. WELFARE FACILITIES

Why welfare facilities?

Work in the construction industry is arduous; itinvolves much manual or physical activity. It is alsohazardous and dirty. Good welfare facilities not onlyimprove workers' welfare but also enhanceefficiently. .

Welfare facilities such as the provision ofdrinking­water, washing, sanitary and changingaccommodation, rest-rooms and shelter, facilities forpreparing and eating meals, temporary housing,assistance in transport from place of residence tothe work site and back, all help to reduce fatigueand improve workers' health (figure 10). Thefacilities may be provided and maintained by onecontractor for all workers or by individual

j

1 "I'

J'. ~. I

Figure 9. Make sure that the chosen personal protective equipment gives adequateprotection

contractors.

Sallitary facilities

National laws usually prescribe the type, number andstandard of sanitary facilities which should be·provided, but as a general guide the followipg shouldbe regarded as a practical minimum:

o a sufficient number of water flush-typelavatories for men when this is practicable,including sufficient urinal accommodation;chemical lavatories may be used otherwise;

o a sufficient number of separate water flush­type lavatories for women when this ispracticable; again, chemical lavatories may bean alternative;

o the accommodation should be designed andconstructed so as to screen the occupants fromview and afford protection against the weather;

o the accommodation should be separate fromany messroom or rest-room;

o a smooth and impermeable floor;

o effective natural and/or artificial lighting andventilation;

o at least 30 m. from any well;

o Construction for easy maintenance andcleaned out at least daily.

Washillgfacilities

Work in the construction industry is often dusty and

35

dirty; it may also involve handling chemicals andother dangerous substances. It is therefore, importantto wash hands and body regularly in order to:

o prevent chemicals contaminating food and sobeing eaten during snacks or meals, beingabsorbed through the skin or being carriedhome;

o remove dirt and grime, which can also beingested and cause sickness and disease;

o maintain basic hygiene.

When construction work involves the maintenanceof or alterations to existing buildings, it is oftenpossible to use the facilities which form part of thebuilding. Otherwise, washing facilities should beprovided to the following standards:

o One wash-basin for every 15 workers with asufficient supply of water and an adequatemeans of removing waste water;

o Soap, in the form of cake soap, or liquid orpowder soap in a special dispenser, to facilitatequick and proper washing; nail-brushes areneeded where poisonous substances are used;

o Suitable drying facilities such as pap e rtowels, roller towels (or i n d i v i d u a I

- towels for each worker) or electric hand­dryers;

o For facilities likely to be of longer duration,mirrors and shelves at each washing pointwhich will help to keep the place tidy andclean;

o Where workers are exposed to skincontamination by chemical substances or by

_,?o _

Figure 10.

36

Suitable washing facilities and lavatories help protect the health of workers

4

oil or grease, a sufficient number of showers,which should be disinfected daily;

o Facilities should be covered to provideweather protection, and effectively ventilatedand lit.

Facilities for supplyingfood and drink, andeating meals

Facilities for supplying food at construction sites canbe particularly important when sites are located inremote areas. Remoteness, together with inadequatetemporary housing which lacks cooking facilities,may give rise to considerable problems for workersin the availability and regularity of hygienicallyprepared and nutritious meals. The problems ofshiftworkers may be even greater. .

To meet the need for proper meals, a choice offacilities should be made available:

o Facilities to boil water and heat food;

o Facilities (including provision of space,shelter, water, heating and garbage bins) forvendors to sell hot and cold food and drink;

o A canteen supplying cooked meals or servingpacked meals, snacks and beverages;

o Arrangements with a restaurant or canteen nearthe work site to supply packed meals.

The meal area

There should be accommodation with tables andseats, protected from the weather, where one caneat in comfort food brought from home or boughtfrom vendors. It should be situated away fromworkstations to minimize contact with dirt, dust ordangerous substances.

Drinking-water

Drinking-water is essential for workers in theconstruction industry, irrespective of the type ofwork they do. You lose severallitres ofwater a daywhile at work and without replacement you graduallydehydrate; the loss is greater in a hot environment.

Arrangements for the supply ofsafe drinking-watermay be:

o 'Individual closed water bottles or containerswhen no other facilities are available, hungclose to the workplace in a shaded place, free

from dust and with plenty ofair in circulation;.cool water helps avoid heat exhaustion.Containers should be cleaned and disinfectedat suitable intervals;

o Drinking-water containers made ofimpermeable materials with suitable covers,kept in a cool, protected place. Unglazedpottery containers keep water cool, and theyshould be kept. in dust-free places. Thecontainers should be cleaned regularly by adesignated person;

o Drinking-water fountains from a public supplywith the water outlet shielded in a manner thatprevents the lips of the drinker from beingplaced against it. Drinking-water fountainsare more hygienic than taps and drinkingvessels;

o . Water taps from a public supply clearlylabelled to distinguish between drinkable andnon-drinkable water. It is preferable to usedisposable cups or to provide a separate cupfor each worker.

Drinking-water should not be placed in sanitaryfacilities, or in places where it can be contarriinatedby dust, chemicals or other substances. Whateverthe source ofwater supply for drinking, it should'beclearly marked as drinking-water in words or withsuitable sign.

Facilitiesfor changing, storing and dryingclothes

Secure facilities at the work site for changing fromoutdoor clothes into work clothes, and for airing and'drying the latter, greatly assist workers with theirpersonal hygiene and tidiness and relieve them ofanxiety over the security of their possessions.

Changing-rooms are particularly important whenworkers change from street clothes into protectiveclotliing and when working clothes become wet ordirty. The facilities should include provision fordrying wet clothes, whether it be outdoor or workingclothing. Separate changing facilities for men andwomen workers should be provided, at least byadequate screening.

. The provision ofadequate seats, mirrors and garbagebins in the changing rooms or close to the lockerswill assist workers in paying attention to personalappearance and clean1iness.

37

Rest breaks

Construction workers begin work early. They starttheir day alert and productive but their activity leveldecreases as the day passes. Fatigue developsgradually before it begins to have marked effects.If you rest before you show signs of being reallytired, recovery is much faster. Short breaks takenfrequently are much better than infrequent longbreaks. Productivity improves with frequent restbreaks.

Frequency ofrest breaks

National law may prescribe the length of a workingday which includes a period or periods for restbreaks. At least o'ne ten-minute break in the momingand one in the afternoon, in addition to the longerbreak for lunch, are essential.

Workers are not just idle during rest breaks, but arerecovering from fatigue and preparing for continuedproductive work. Getting away from a noisy orpolluted workplace helps to relax and recover fromfatigue, and an area with seating and out of directsunlight should be set aside for rest breaks.

Child-carefacilities

Working mothers employed at construction sitesoften need help with the special problems of caringfor their children while they are at work.

Basic provisions

A clean and well-ventilated room, preferably withaccess to an enclosed space, is the main facilityneeded. A few items of simple furniture arenecessary for the children to sit or lie down, and sometoys help. There should be provision for feedingthe children with nutritious meals .at regular timesand, for this, there should also be access to cookingfacilities or a canteen.

It is essential for someone to care for the childrenwhile their motllers are at work, prepare their mealsand feed them regularly. It may be possible formothers tilemselves to take turns to look after thechildren. Mothers, especially nursing mothers,should be able to visit their children duringrecognized breaks from work.

Watch the children's movements

Tragic deaths ofchildren on construction sites occurfrequently. Children should never be allowed towander into or play on sites. There are excavations

38

to fall into, scaffolding to fall .from, hazardousequipment, loose and dangerous building materials,and chemicals lying about.

First aid

Where there is an accident on site and someone ishurt, help can be provided by:

o Calling for help from someone on site trainedin first aid, or in cases of severe injury bycalling an ambulance;

o Preventing others (including yourself) frombeing injured from the same cause;

o Providing life-saving first aid, even ifyou arenot a trained first-aider;

o Reporting the accident at once to yoursupervisor.

Emergency action

There are some situations where one cannot waitfor a trained first-aider. Doing something at oncemight save an injured person's life. Someemergency actions to be taken are as follows:

o Check breathing: tum an unconscious personfrom his or her hack to the side to preventchoking on the tongue; be cautious, keepingin mind the possibility of a neck injury;

o Provide artificial respiration if breathing hasstopped, using tile mouth-to-mouth method;

o Stop heavy bleeding by direct pressure on thewound and by raising the injured limb (do nottry to use a tourniquet);

o Cool a bum with water for some ten minutes,never with anything else - extinguish burning .c10tiling by rolling the person on the groundor wrapping them in a blariket;

o Flush a bum from corrosives, or contanlinationofthe eyes from any chemical, with water forat least ten minutes;

o .Treat shock by lying the injured person on hisor her side; loosen any tight clotiling and coverthe person with a blariket to keep him or herwarm;

o Immobilize a broken limb by bandaging it totwo sticks ifno splint is available, even tightly

rolled newspaper will do.

You should not:

o Move an injured person except to remove himor her from danger;

o Remove any foreign object embedded in thebody;

o Give the person anything to drink - you maymoisten the lips and tongue if asked to;

o Move a broken limb.

Deep cuts and abrasions carry the risk of tetanus(lockjaw) and need to be treated by a doctor.Abrasions, even minor, carry a greater risk ofinfection than an open wound. After stoppingbleeding, clean cuts and abrasions thoroughly withsoap and water before covering them with a bandage.Make sure your hands are clean. Always wash yourhands with soap after you have finished.

Equipmellt alld traillillg

Construction sites are dangerous places, and fIrst­aid and rescue equipment should always beavailable. What is needed will depend on the sizeof the site and the number of workers employed,but there should be at least a stocked first-aid boxand a stretcher and blanket - the stretcher should beof a type which can be raised and lowered to andfrom upper floors. On large sites, and always wheremore than 200 people are employed, there shouldbe a properly equipped first-aid room or hut.

. On any construction site ofremarkable size, at leastone person on every shift should have been trainedin first aid to a nationally recognized standard.

Movillg all illjuredpersoll

In principle, never move an injured person until atrained first-aider or a doctor can direct you.However, when someone is at risk of further injuryand has to be removed to a safe place, lift him or herby using a stretcher or a blanket. If you are aloneand must rapidly move an injured person out ofdanger, then a good way is to drag him or her headfirst by the clothes.

Illvestigatioll

After an accident, leave the site equipmentundisturbed as far as it is safe to do so, so that the

cause ofthe accident can be properly investigated.Make sure also that any objects and equipmentinvolved remain untouched. This is important ifproper measures are to be taken to prevent arepetition ofthe accident.

Fire precautiolls

Fires on construction sites arise from the misuse ofcompressed gases and highly flammable liquids,from the ignition of waste material, wood shavingsand cellular plastic materials, and from the failureto recognize that adhesives and some floor and wallcoatings are highly flammable.

Iffire breaks out, get someone to call the fire station.Do not continue trying to fight the blaze yourself iflarge quantities of fumes are being emitted in aclosed space. Get out as fast as possible.

Every individual on site should be aware of the firerisk, .and should lmow the precautions to prevent afire and the action to be taken if fire does break out.

IffIre breaks out, get someone to call the fire station.Do not continue trying to fight the blaze yourself. Iflarge quantities of fumes are being emitted in aclosed place, get out as fast as possible.

Fires are sometimes caused by carelessness in dryingwet clothes. Heaters for this purpose, gas, oil orelectric, should be mounted on and backed with non­flammable material, and enclosed in a stout wiremesh with effective air space to prevent clothingbeing placed directly upon them.

Ifyou have to use a blow lamp or torch, or weldingor burning equipment in tlle course of your work,make sure that there is no fire risk to adjacentmaterials such as roof timbers. Many fires withdisastrous consequences start from this source.Sparks can travel a long distance.

Everyolle Oil site should be trailled to:

o . Know oftwo unobstructed ways offthe site ifthere is a fire or other emergency;

o Know how to raise the alarm;

o Know where fIrefIghting appliances are kept;

o Be able to use the frrefIghting appliances; and

o Be able to select the correct type of portablefire extinguisher for specific types of fire, asshown in the following table:

39

Table: Emergency fire fighting measures

· Type of portablefire extinguisher

Pressurized water

Carbon dioxide

Dry chemical powder

Foam

40

Action

Cools fuels rapidly - for fires inordinary combustible buildingmaterials

Excludes oxygen

Interferes with the combustionprocess

Excludes oxygen, limited cooling

Forms blanket over flammableliquids

Suitability and dangers

Conducts electricty - not to be used forlive electrical equipment or oil fires

Displaces oxygen when used inconfined spaces -

Re-ignition may occur in overheatedliquids such as hot bitumen

Use in confmed areas may lead to areduction in visibility

Non-conductor of electricity and maybe used on live electrical equipment

Re-ignition may occur in overheatedliquids

Conducts electricity - not to beused for live electrical components

Gives better control over re-ignitionthan carbon dioxide and dry powder

Better suited to extinguish fire inoverheated liquids such as bitumenboilers and oil tanks

#-~

PUBLICATIONS· REVIEWPUBLISHED BY UNCHS (Habitat)

The Istanbul Declaration and TheHabitat Agenda

The Istanbul Declaration and the Habitat Agendatogether constitute a new social contract towardsimproving human settlements conditions in theworld's cities, towns and villages. The presence ofso many representatives ofso many different socialpartners in Istanbul, Turkey during the second UnitedNations Conference on Human Settlements (HabitatII), represents something new in the globaldevelopment agenda.

The Habitat II Conference has been referred to asthe "Partners Conference". Never before have somany different actors been directly involved in theUnited Nations conference. In addition torepresentatives of non-governmental organizations(NGOs), which have generally been represented inprevious conferences, the Habitat II Conferencebrought together representatives of a whole rangeofdifferent other actors in a series of"Forums", i.e.,local authorities, foundations, the private sector,trade unions, academies ofscience, parliamentariansand professional organizations.

The fact that more than one billion human beingslack adequate shelter, is one ofthe major challengesto humankind today. Another major challenge isthe global process of urbanization. By t he tum ofthe century more than half of humankind will liveill urban areas. It was thus no coincidence that theSecretary-General of the United Nations called theHabitat II Conference - "City Summit". The two .main themes of the Conference - "adequate shelterfor all" and "sustainable human settiementsdevelopment in an urbanizing world" - thus havedirect implications for the day-to-day life of everyhuman being.

The Istanbul Declaration and the Habitat Agendatogether constitute a reaffirmation of thecommitment to better standards of living andincreased freedoms for all humankind, as well as toimprovement of the quality of life within human

settlements and the progressive realization of thehuman right to adequate housing. The Habitat IIConference further reaffIrmed that human beings areat the centre of sustainable development, as well asthe interdependence ofurban and rural development.

The challenges of human settlements are global.Many of the problems, however, are specifIc,requiring local solutions. The Istanbul Declarationand the Habitat Agenda together highlight the focuson local authorities and on the wide range of otherinterested parties in the struggle to improve thehuman settlements conditions in the world's cities,towns and villages. The challenge to us all isformidable, yet we cannot afford to fail.

This publication has been prepared with the purposeoffacilitating the reading, understanding and use ofthese very important documents. A detailed subjectindex has been provided which facilitates quick andeasy reference to issues of given interest.

172 pp. HS/441/97E, ISBN 92-1-131322-8

41

EnU ..lrl)'nr, Jllkarla

136pp. ISBN I 85972 5120, 1997

Crowding lind Health inI,ow-Income Settlements

!1

I

~\ndrcnzil~tL"i

lIcnriJi JCII~II1' t:.l:i!r A'ab\'O~rul}'II·St.:pllcml

~@'~.U"ClHI IH.....;,. .~I'

,1c.'R f.luIISflo;1{aMChiuleli SuJjadixi~i14 U,'jl)'ng~~ntOlH~

Human Settlement InterventionsAddressing Crowding and Health Issues

Urban growth in developing countriesis increasingat a pace higher than ever before. Currentprojectionsindicate that by the year 2025, more than two-thirdsof the world's population will be living in cities.The demand for urban space is also rising in tandemand the availability ofadequate living space is underserious threat from other competing demands.Speculative land prices in the cities have ensuredthat the poor, who constitute nearly one half of theurban population, are increasingly crowded in inner­city slums or are progressively marginalized tosquatter settlements at the city peripheries.

Wherever they are, the urban poor suffer not onlyfrom overcrowding of space but also fromovercrowding of the basic services such as drinkingwater supply and sanitation. They also face the bruntof urban pollution, be it indoors from poorventilation or outdoors from lack of adequatedrainage and waste disposal. The inevitableconsequence is that the poor are exposed to dualhealth risks, one related to poverty and the otherrelated to pollution.

..•..",;,.

42

Crowding and Health in Low-IncomeSettlements

Today the lives ofmore people than ever before arebeing affected by conditions ofabsolute poverty andinadequate shelter, including homelessness. Thissituation is threatening standards of health andsecurity and even life itself. The Preamble of theHabitat Agenda adopted by the second United

. Nations Conference on Human Settlements (HabitatII), held in Istanbul from 3-14 June 1996, states thateveryone has the right to an adequate standard ofliving for themselves and their families, includingadequate food, clothing, housing, water andsanitation, and to the continuous improvement ofliving conditions.

Inadequate shelter is, among other things,characterized by a lack of living space, alsoexpressed by high in-house crowding. In slums andsquatter settlements, where the majority or urbandwellers in developing countries live, people haveto suffice with minirnalliving space. Often a wholefamily has to squeeze into one room, which is usedfor basic needs of life such as sleeping, cooking,working, learning and playing. The detrimentaleffects on health of such cramped living conditionscoupled, in most cases, with lack ofclean water andsanitation can be imagined.

For UNCHS (Habitat), human health and quality oflife are at the centre of the effort to developsustainable human settlements. It was against ·thisbackground that the Centre launched an appliedresearch project on crowding and health. The projectaims at providing urban managers, engineers,architects and health planners with information onthe interrelationship between crowding and healthand suggestions on requisite human settlementinterventions. This publication is one of severaloutputs emanating from the project and focuses onthe findings of a series of studies conducted inJakarta, Indonesia establishing the health effects ofcrowded living conditions. Other cities covered bythe project were Accra, Ghana and Bissau, GuineaBissau.

Despite the general perception ofthe adverse effectsof overcrowding on the health of residents in low­income settlements, the shelter sector has not yetbeen able to take advantage ofthe health argumentsto stimulate increased investment in the sector,primarily because there has been very little precise,epidemiological data available so far on howcrowding affects community health. The limitedinterdisciplinary understanding between the humansettlements and health sectors has also come in theway of coordinated action in this area. Fewarchitects, planners and engineers are aware of thehealth consequences oftheir technical choices, and,simihirly, few health officials are informed of thepotential impact of human settlement relatedinterventions on community health.

This publication is the outcome of the UnitedNations Centre for Human Settlements (Habitat)'sefforts to bridge the knowledge gap in this importantarea and to improve the understanding among sectorprofessionals on environmental health aspects ofhuman settlements. The publication presents thefmdings of a detailed field study carried out by theCentre in Ghana, Guinea Bissau and Indonesian,over a span ofthfee years (1993-1995) to establishprecise epidemiological relationship betweenovercrowding and community health and to developrelated human settlement interventions.

HUMAN SETTLEMENTINTERVENTIONS ADDRESSIN(;CROWDING AND HEAI~fH ISSUES

UNITED NATIONS CENTRE FDR HUMAN SETTLEMENTS IHabita\!

132 pp, HS/374/95E, ISBN-92-1-131-288-4

43