003 part1-effect of air pollution

7/31/2019 003 Part1-Effect of Air Pollution

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Effects of Air PollutionPart I Air Pollution : - Effects Of Pollutants

And Public Policy Concern

2103555 Engine and Emissions Control


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Effects of Air PollutionOne of the difficulties in coping with the air pollution lies in thevariety of its effects on people.

A farmer is most interested in its effects on his crops; A house will complain that dirt and soot soil clothing and furniture; A traveler, may be inconvenienced by low atmospheric visibility; A large segment of general public is concerned with the possible

health effects of polluted air.

The five most common effects of air pollution are;(i) Reduction in visibility(ii) Economic damage to property

(iii) Annoyance to human senses(iv) Damage to health(v) Substantive changes in the ecology of the natural environment


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Effects of Air Pollution: Limited Visibility

Restriction of visibility is the most widely noticed andprobably least understood of all effects of air pollution.

Smoke and dust clouds that are sufficiently dense todarken the sky will obviously limit visibility.

Public objection to reduced visibility stems from two

factors, transportation hazards and

delays and aesthetic considerations.

The blotting of the horizon in a smoke filled valley can

well discourage tourist trade and reduce its land value.Eventually the problem must be faced on a cost benefitbasis.


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Effects of Air Pollution: Economic

Damage to Property

Air pollution damage to property includes damage to materials,vegetation and animals as well as interference with production and

services.

Air pollution damages materials chiefly by corrosion of metals,presumably from acidic pollutants in atmospheres.

The most important pollutant is sulphur dioxide, SO2, which is

released in great quantities by the combustion of sulphur containingfuels. In the presence of oxygen SO2 is converted into sulphurtrioxide, SO3, which in turn combines with water vapor in theatmosphere to form sulphuric acid.

Deposition of this acid on metal parts of equipment, building roofs

results in considerable loss in most urban communities. Hydrogen Fluoride (h2F2) and Hydrochloride (HCl) will also react

with water vapour to form highly corrosive droplets of fog.


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Damage to Property

Another form of property damage is the 'rubber cracking'.Principal areas are the sidewalls of tyres and various

forms of electrical insulation. This damage is caused byhigh ozone content in the atmospheric air.

Hydrogen sulphide is a common cause for the damage

to the painted surfaces by reaction with the lead inpaints.

Temporary damage results from the soiling of surfacesby smoke, soot and dust fall.

Losses most commonly encountered are the additionalcost of laundering, cleaning and redecorating thebuildings.


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Damage to Property

The pollutants like SO2, H2, F, Cl2, HCl, oxides ofnitrogen, H2S, NH3, Hydrogen Cyanide, Mercuryvapour, Ethylene etc, commonly cause vegetationdamage. The nature of damage varies with the toxicant,usually in the form of chlorotic marking (disappearanceof green colour), silvering or bronzing of the underside ofthe leaf, leading to death of the plant in extreme cases.

The extent of damage to an individual plant alsodepends on many factors, e.g., the pollutant, type of soil,

relative humidity, amount and type of plant foodavailable, stage of growth, pollutant concentration, timeof exposure and amount of light.


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Damage to Property

The effect of pollution on animals is the damage causedto them by grazing in areas where grasses arecontaminated by fluoride dusts or have absorbed fluoridecompounds from the atmosphere.

The chief effect of ingested fluorides on animals isfluorosis, an accumulation of fluoride in the bonestructure of the animal leading to weight loss andlameness.


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Damage to Property

Interference with production and services includes avariety of secondary effects occasioned primarily by

other air pollution effects.

Automobile and air traffic delays caused by poor visibilityand a general lethargy in human activities because of

depressing nature of some effects.

Related interference to services of more direct economicconsequence is loss of retail trade, loss of tourist trade

and reduction in land and improvement values.


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Effects of Air Pollution:

Annoyance to senses of people

This category, of air pollution effects includes a multitude ofreactions that can be generally divided into two classes;

(a) Eye, nose and throat irritation(b) Odours

When a known irritant escapes into the atmosphere it is easy torelate the cause and effect.

Some times a mixture of unknown composition and unsuspectedirritability is released into atmosphere and carried away by air. It isdifficult to trace such a source.

Nose and throat irritation have been often reported as effects of airpollution. Odour is also a subjective response of people and is more difficult to

define than eye irritation. This is particularly true because an odourobjectionable to one person may be pleasing to another.


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Effects of Air Pollution: Damage to health

Air is necessary for the survival of man and there is no such thing asabsolutely pure or clean air, nor is there any such thing as an

absolutely safe contaminant. At some concentration in air any gas or aerosol will damage health. The specific concentration at which a contaminant will damage

health depends upon how the word health is defined, the nature ofcontaminant, the length of time the air containing the specific

pollutant is breathed or in contact with the receptor, and the state ofhealth of the receptor. The state of health of a receptor is a highly important variable.

Health is defined (WHO) as a state of complete physical, mentaland social well being and not merely the absence of disease or

infirmity. A further complication is the subjective nature of health,which is the reason for the emotion approach to matters concerningair pollution.


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There are certain factors that appear to be incontestable. People have died as a result of polluted air as evidenced by several air

pollution episodes in London, Donora and other places. Mandy of thesepeople many not have died as a direct result of air pollution but air pollutionwas a contributing factor.

There is a concentration or a dosage of specific air pollutants, which evokesvarious physiological responses from receptors.

Certain contributions of atmospheric pollutants aggravate the symptoms of

chronic pulmonary disease and possibly other diseases. Some pollutants irritate sensitive membranes, those of the eyes, nose,

throat, and lungs particularly, but the irritation varies greatly from oneperson to another.

Health effects that may be caused or aggravated by overcrowding,

occupation, working conditions, nutrition, habits (such as smoking, climateand other variable. It is probable but not proved conclusively that mixture of pollutants will affect

some people more than would be predicted by the additive effects ofindividual pollutants.


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The three common means for determining the effects ofvarious concentrations and dosages of pollutants onpeople are;

(i) Experimental exposures of men and animals undercontrolled conditions to various concentrations and

dosages.(ii) Clinical Studies involve observations made onsubjects who are or were exposed to atmosphericpollutants under controlled conditions.

(iii) Epidemiological studies for relationships betweenthe distribution of specific diseases in human populationand the factors that determine the distribution.


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(i) Experimental exposures of men and animals undercontrolled conditions to various concentrations and

dosages. Like all biological studies, the results must be subjected

to rigorous statistical analysis. Experimental exposures of human beings must be

limited to low concentrations that will not result in seriousillness.

Types of effects noticed and measured are detection ofodor, eye-nose-throat irritation, variation in lung capacity,

breathing frequency, pulse rate, reduction in physicalactivity, darkness adaptation and many otherphysiological responses.


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(ii) Clinical Studies predominantly involve observations

made on subjects who are or were exposed toatmospheric pollutants under controlled conditions.

Patients visiting physicians to complain of symptomssupposedly caused by living in polluted areas may upon

observation yield clinical data of importance.

Studies on downtown traffic police, truck drivers andother occupational groups may yield valuable

information.


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(iii) In Epidemiological studies for relationships between thedistribution of specific diseases in human population andthe factors that determine the distribution.

Many compare mortality records, hospital admissions,morbidity (illness) records, absenteeism and other health

related data from several geographical areas with levelsof atmospheric pollutants in the same area to determineif significant correlation may be discovered.

To avoid misinterpretation, population under study must

be carefully screened for smoking habits, occupationalexposures etc. that might prejudice the results of thestudy.


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Special Health Effects(i) Chronic pulmonary diseases (bronchitis, asthma, emphysema) is

aggravated by sufficiently high concentrations of SO2, NO2, Particulatesand photochemical smog

(ii) It has been difficult to relate atmospheric pollution to lung cancer, unlikethe more convincing relationship between heavy cigarette smoking andlung cancer.

(iii) Cardiovascular diseases are related to pollutants in that any pollutantplacing sufficient stress on the pulmonary function may affect the heart.

(iv) Carbon monoxide ties up the haemoglobin in the blood to a sufficientamount to put added stress on those suffering from cardiovascular andpulmonary diseases.

(v) Photochemical smog irritates the eyes but apparently does not damagethem. Persons with pulmonary diseases may suffer aggravation ofsymptoms.

(vi) A variety of particulates, particularly pollens, irritate asthmatic attacks.(vii) Various gases, e.g., H2S and ammonia have noticeable odours at lowconcentrations.

(viii) Certain heavy metals, e.g., lead may enter the body through the lungsand accumulate in the bones and various tissues. In the case of lead,however, the amounts which enter the body by way of food and drink are

more important.


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Summary of Health Effects for Criteria Pollutants

Temporary breathing impairment for asthmatics.

Contributes to same symptoms as PM2.5 above

SO2

Coarse particles (PM10) aggravate respiratory conditions such as asthma.

Fine particles (PM2.5) are associated with: (a) increased hospital admissions & ER

visits for heart & lung disease (b) increased respiratory systems and disease (c)

decreased lung function, and (d) premature death

PM10 and PM2.5

Short-term (1-3 hrs.) and prolonged (6-8 hrs.) exposures linked to increased hospital

admissions and ER visits for respiratory causes.

Repeated exposure (a) increases susceptibility to respiratory infection (b) results inlung inflammation, and (c) aggravates pre-existing diseases such as asthma

Significant decreases in lung function, particularly during exercise.

Increased incidence of respiratory symptoms such as chest pain & coughing.

Long-term exposure at moderate levels may cause irreversible changes in the lung

leading to pre-mature aging of lungs and/or chronic respiratory illnesses.

O3

(Ground level)

Short-term (


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Summary of Health Effects for Criteria Pollutants

Figure 4 Effects of CO exposure on human.


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Effects of Air Pollution: Ecosystem Changes

Some effects of pollutants may occur far fromthe site at which they are emitted and may

induce changes in the environment.

For example, storms, cloud formations, and increasedrainfall in areas downwind from large pollution sources.

Beyond these changes in regional environmentalsystems, other evidence suggests that man causedpollution discharges may now be leading to ultimatechanges in global weather patterns and to other

alterations in the planetary ecological system.

003 part1-effect of air pollution

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