(IAQ)

Introduction

A chemical having at least one carbon and hydrogen atom in its molecular structure is referred to as Organic Compound

Organic compounds are divided mainly based on their vapor pressure at room temperature into:

Volatile Organic Compounds (VP > 1 mm of Hg)

Semi-Volatile Organic Compounds(10E - 7 > VP < 1 mm of Hg)

Non-Volatile Organic Compounds (VP < 10 E -7 mm of Hg)

Introduction(contd.…)

EPA conducted comprehensive studies on Indoor Air Quality in U.S. under the name of Total Exposure Assessment Methodology (TEAM)

The study showed that the targeted 22 chemicals (Pollutants) had higher concentrations indoors than outdoors

Formaldehyde (used in resin) is suspected of being carcinogenic at present indoor levels which may be a critical problem

The 22 Targeted VOCs by the U.S. EPA (1986)

Vinyl Chloride Methylene Chloride Chloroform Carbon Tetrachloride

1,1,1-Trichloroethane

Trichloroethylene Tetrachloroethylene Benzene

o-Xylene m,p-Xylene m,p-Dichlorobenzene Ethylbenzene

Styrene 1,2-Dichloroethane 1,1,1,2-Tetrachloroethane

1,1,2,2-Tetrachloroethane

n-Butlyacetate Hexachloroethane Decane Chlorobenzene

Ethylphenol Acrolein

Pollutants associated with various activity levels

Cleaning windows Ammonium hydroxide

Spots/textiles Tetrachloroethylene, Trichloroethylene, Methanol, Benzene etc.

Soaps/detergents Polyether sulphates, Alcohol, Sulfonates, alkylsodium isothionates

Oven Sodium hydroxide, Potassium hydroxide

Drain/toilet bowl Sodium hydroxide, Lye

Vacuuming of carpets

Dust

General cleaning Ammonium hydroxide, Lye, Chlorine, Sodium hypochloride etc.

Pollutants associated with various activity levelsPainting/varnishing Toulene, Xylene, Methyl chloride, Heavy metals, Pigments,

Methanol, Ethylene glycol, Benzene

Application of Pesticides

Organophosphates, Carbamates, Pyrethroids

Gardening Pesticides, Herbicides, Gasoline, Oil, Fertilizers

Cooking Combustion products, Formaldehyde

Aerosol cans usage Propane, Butane, Methylene propellants, Isobutane

Disinfectants Sodium hypochloride, Quaternary ammonium salts, Phenols, Pine oils

Smoking Tobacco smoke

Furniture/carpets off gassing

Formaldehyde, VOCs

Source: Sterling et al., 1990.

Health effects due to exposure to VOCs Health effects due to exposure to VOCs at typical Industrial Environments are

derived from animal studies which can be related to humans

Little is known about the chronic effects of a mixture of VOCs (particularly at low concentrations)

Indoor Environments (residences in particular) have different types of exposure to the pollutant:

High Concentration but for a short period

Low concentration but for a longer period

In short-term exposure individuals are exposed to one or a mixture of compounds depending on their activity levels

Health effects due to exposure to contaminants depends on:

Exposure time

Pollutant types

Health status of the individual at the time of exposure

Pollutant concentration (an important factor)

Health effects due to Aldehyde Exposure

Formaldehyde

Formaldehyde is colorless but has distinct pungent odor that makes it detectable (even at concentrations as low as 0.05ppm)

Formaldehyde concentration is higher in mobile homes and houses with Urea Formaldehyde Foam Insulation (UFFI)

Formaldehyde has both acute and chronic health effects like: Irritation of eyes, upper airway, etc

Health effects due to formaldehyde exposure at various concentrations

0.0 - 0.5 ppm None reported

0.05 - 1.5 ppm Neurophisiological effects

0.05 - 1.0 ppm Odor threshold limit

0.01 - 2.0 ppm Irritation of eyes

0.1 – 25 ppm Irritation of upper airway

5 – 30 ppm Irritation of lower airway and pulmonary effects

50 – 100 ppm Pulmonary edema, inflammation, pneumonia

> 100 ppm Death

Source: NAS, 1981.

Studies on formaldehyde exposure

Where: e – Exposed and ne – Non-exposed.

Eye irritation: e, 81%; ne, 17%;Throat irritation: e, 57%; ne, 22%;Fatigue: e,81%; ne, 22%;Headache: e, 76%; ne, 11%;

Mobile home: 0.12 – 0.16 ppmBuilding: not reported

21 workers in mobile homes and 18 workers in buildings

Menstrual irregularities: e, 35%; ne, noneEye irritation: e, 55%, ne,15%;Headache: e,80%; ne, 22%;

Mobile home: 0.24 – 0.55 ppmBuilding: 0.05 – 0.11 ppm

70 employees in 7 mobile homes and 34 non-exposed employees in 3 buildings

Wheezing: e, 60%; ne, 10%;Burning skin: e, 70%; ne, 10%;

Not reported1396 residents of UFFI homes and 1395 of non-UFFI homes (Thun et al.,1984)

Health Effects due to Exposure to Formaldehyde and Ethers

Formaldehyde at high concentration can cause buccal cavity cancer and nasopharyngeal cancer in human beings

Low concentrations can also be fatal or can cause serious threat to health and the risk of developing cancer is:

1 in 10,000 Exposed for 10 yrs at 0.07 ppm

1 in 5,000 if exposed at 0.1 ppm

The Ethers cause anesthetic effect in humans, which leads to pulmonary edema, vomiting, headache and nausea

Health effects due to Exposure to high concentration of ketones

Narcosis

Nausea

Headache

Dizziness

Irritation of mucous membrane

Loss of co-ordination

Effects of Formaldehyde exposure on human health

0

20

40

60

80

100

120

140

160

1

Series1Series2Series3Series4Series5Series6Series7Series8

no effectsneurophysiologiceffects

odor thresholdlimit

irritation of eyes

irritation of upper airway

irritation of lowerairway and pulmo--nary effects

pulmonary edema, inflammation,pneumonia

death

0.0-0.5 0.05-1.5 0.05-1.0 0.01-2.0 0.10-25 5-30 50-100 over 100conentration of formaldehyde in PPM

Health effects due to exposure to Aliphatic and Aromatic Hydrocarbons Propane and more complex hydrocarbons depress the central nervous system

and cause mild irritation of the mucous membrane

Cyclic Hydrocarbons have same effect as the aliphatic hydrocarbons

Aromatic Hydrocarbons cause:

irritation of mucous membrane, eyes and respiratory system

pulmonary edema

pneumonitis

Benzene, a hydrocarbon, is a human carcinogen

Health effects due to exposure to Chlorinated Hydrocarbons

High volatility of the chlorinated hydrocarbons leads to substantial exposure through inhalation

Chlorinated hydrocarbons cause

Irritation to eyes

Irritation to skin

Irritation to respiratory system

Severe functional

Severe damage to the liver and kidneys

Changing exposure limits of Chlorinated HydrocarbonsPollutants (concentration in ppm)

Year 1958 1960 1970 1980 1990

Chloroform 100 50 B,10

Methylene chloride 500 200 100

Methyl chloride 50 B

Vinyl chloride 500 100 B,A2,A1

Trichloroethylene 200 100 50 B

Tetrachloroethane 200 100 50

1,2 – Dichloroethane 100 20 B

Methyl chloroform 500 200

Carbon tetrachloride 25 10 B

A1, human A2 animal

B, suspected Human

Source: Henschler, 1990.

Health effects due to exposure to Alcohols Compounds like phenol and cresol cause

Difficulty in swallowing

Diarrhea

Tremors

Convulsions

Ingestion of Methanol causes damage to the optical nerve leading to blindness

Mixture of VOCs

Chemicals are found in a room generally in a mixture form

Synergistic interactions of pollutants leads to different chemical compounds

Any building related health effects due to indoor pollutants is referred to as Sick Building Syndrome (SBS) or Tight Building syndrome (TBS)

Exposure Limits

Threshold limit Value (TLV) is the level of a chemical that ACGIH deems safe for a worker to be exposed to day after day

OSHA, ASHRAE recommended one-tenth of TLV as maximum allowed indoor concentration

Based on several studies American Industrial Hygiene Association (AIHA) adopted 5 mg / m³ as a guideline for VOCs

ASHRAE (62-1999) suggests the following air exchange rate’s : -- Residential Facilities: minimum of 15 ft³ /person/ min -- Commercial and Institutional facilities: 15 to 60 cf/person/min

Formaldehyde Formaldehyde, a major VOC, is released mainly from materials that contain

UFFA, a type of resin. These materials can include: Building materials

Home/Office Furnishingsmedium density fiberboard particle board carpet electrical switches

Formaldehyde is used in resins because of its following properties

Excellent bonding properties

Inexpensive

Formaldehyde uses and potential indoor sources

Products Examples

Paper products Grocery bags, wax paper, facial tissue, paper towels, disposable sanitary products

Stiffness, wrinkle resisters and water repellents

Floor covering (rugs, linoleum, varnishes, plastics), carpet backings, adhesive binders, fire retardants, wrinkle free clothes, pressed clothes

Insulation Urea Formaldehyde Foam insulation (UFFI)

Combustion devices Natural gas, kerosene, tobacco smoke

Pressed-wood products Plywood, particle board, decorative paneling

Other sources Cosmetics, deodorants, shampoos, fabric dyes, inks.

Formaldehyde emission rates of several building materials

Material Emission rates (micro gms/m2 day)Medium density fiberboard 17,600 – 55,000

Hardwood plywood paneling 1500 – 36,000

Particle board 2000 – 25,000

UFFI 1200 – 19,200

Softwood plywood 240 – 720

Paper products 260 – 680

Fiber-glass products 400 – 470

Clothing 35 – 570

Resilient flooring < 240

Carpeting 0 – 65

Upholstery 0 – 7

(Source: NAS; Pickrell,1983; Matthews, 1985)

Formaldehyde The concentration of HCHO fluctuates with

Seasonal variation of temperature

Relative humidity, and

Moisture content of several materials

HCHO is produced during the various processes such as

Operation of combustion appliances (gas or kerosene stove, fireplace etc.)

Smoking

Formaldehyde concentration in homes resulting from combustion appliances

Winter SummerCombustion sources

No. of homes

Mean (ppm)

Std. Dev.

No. of homes

Mean (ppm)

Std. Dev.

None 31 0.046 0.035 34 0.059 0.043Woodstove 63 0.053 0.032 62 0.082 0.038

Kerosene heater 39 0.055 0.028 42 0.067 0.033Kerosene heater and woodstove

17 0.05 0.026 13 0.075 0.032

Smoker 33 0.046 0.025 25 0.055 0.031Smoker and woodstove

41 0.048 0.024 39 0.068 0.032

Smoker and kerosene heater

32 0.042 0.018 32 0.054 0.026

Smoker, woodstove and kerosene heater

25 0.047 0.027 22 0.06 0.025

Source: Hawthorne and Matthews, 1985

Sources of VOCs

VOCs other than Formaldehyde are released from several other products such as

Combustion products

VOCs emitted as a result of incomplete combustion of fuel release chemicals like methane, ethane, propane and hexane

Wood also releases Polynuclear Aromatic Hydrocarbons (PAH)

Tobacco smoke (depending on the number of cigarettes smoked)

0.100.100.030.090.30Trichloroethylene

0.1065.00.300.60Tetrachloroethylene

12.540.025.200.17Styrene

0.501.000.070.20.4Methyl chloroform

Limonene

Ethyl benzene

0.200.040.100.15Chloroform

0.181.00Carbon tetrachloride

0.20.70.60.9Benzene

0.750.81,2-Dichloroethane

LubricantsFoamFabrics CoatingsAdhesivesCompound

(in ppm)Emission

Emissions of Organic Chemicals from Household Products

1.900.090.07Trichloroethylene

0.700.080.20Tetrachloroethylene

0.151.100.100.1533.50Styrene

0.200.100.10Methyl chloroform

0.40Limonene

0.20527.80Ethyl benzene

0.050.90Chloroform

0.754.20Carbon tetrachloride

0.690.100.90Benzene

3.251,2-Dichloroethane

deodorantsCosmeticsTapeRubberPaintsCompound

in ppmEmission

Emission of Organic Chemicals from Household Products

0.070.060.010.11Trichloroethylene

2.000.05Tetrachloroethylene

0.300.020.050.17Styrene

0.100.190.030.01Methyl chloroform

1.801.00Limonene

0.80Ethyl benzene

10.004.850.23Chloroform

0.200.040.00Carbon tetrachloride

0.401.100.021.85Benzene

0.061,2-Dichloroethane

Ink pensMisc. house wares

Electrical equipment

Health & beauty aidsCompound

(in ppm)Emission

Emission of Organic Chemicals from Household Products

Emission (ppm)

Compound Paper equipment Photo film Photo equipment

1,2-Dichloroethane

Benzene 0.03 1.51 0.04

Carbon tetrachloride 2.50

Chloroform 0.10 2.50 0.10

Ethyl benzene 10.50 0.13

Limonene

Methyl chloroform 0.26 0.08 1.90

Styrene 0.04 0.10

Tetrachloroethylene 0.42

Trichloroethylene 0.10 0.03 0.13

Emission of Organic Chemicals from Household Products

Source: Ozkaynak et al., 1987.

Sources of VOCs

Carpets and paints

Carpets and paints are large contributors and cover nearly 95% of room surface area

VOCs are emitted by the use of oil-based paints

Carpets emit VOCs at first but gradually VOC emission rates diminish

Newly carpeted room should be properly ventilated  for several days after installation, or carpets can be pre-ventilated in a humidity controlled warehouse

Sources of VOCs

Water

During treatment of water before supply under go several processes.

Common by-products of this treated water are: Chloroform

Carbon tetrachloride, and

1,2,3-trichloropropane

Human beings

Acetone :1200 * 10 E (-6) / m³

Ethanol :240 mg/m³

Emission rates of organics by humansEmission rate

Organic compounds Typical conc.(389 people in class (ppb))

Lecture class 225 people

During examination

Acetone 20.6 +/- 2.8 50.7 +/- 27.3 86.6 +/- 42.1

Acetaldehyde 4.2 +/- 2.1 6.2 +/- 4.5 8.6 +/- 4.6

Acetic acid 9.9 +/- 1.1 19.9 +/- 2.3 26.1 +/- 25.1

Allyl alcohol 1.7 +/- 1.7 3.6 +/- 3.6 6.1 +/- 4.4

Amyl alcohol 7.6 +/- 7.2 21.9 +/- 20.8 20.5 +/- 16.5

Butyric acid 15.1 +/- 7.3 44.6 +/- 21.5 59.4 +/- 52.5

Diethylketone 5.7 +/- 5.0 20.8 +/- 11.4 11.0 +/- 7.7

Ethyl acetate 8.6 +/- 2.6 25.4 +/- 4.8 12.7 +/- 15.4

Ethyl alcohol 22.8 +/- 10.0 44.7 +/- 21.5 109 +/- 31.5

Methyl alcohol 54.8 +/- 29.3 74.4 +/- 5.0 57.8 +/- 6.3

Phenol 4.6 +/- 1.9 9.5 +/- 1.5 8.7 +/- 5.3

Toulene 1.8 +/- 1.7 7.4 +/- 4.9 8.0

Carbon monoxide 48,400 +/- 1200

Ammonia 32.2 +/- 5.0

Hydrogen sulphide 2.73 +/- 1.32 2.96 +/- 0.68

Carbon dioxide 642,000 +/- 34,000 930,000 +/- 52,000

Source: Wang, 1975

Most commonly used analytical type air quality monitoring equipment

Personal monitors

Lightweight monitors convenient to carry and to handle

Portable monitors

These can moved during sampling

Stationary monitors

These can operated only from a fixed place

Principles followed by collectors during data collection

Air Displacement

Condensation

Air is passed through a U-tube followed by subsequent cooling of the sample

 Gas washing or Absorption

The contaminated air or the sample is passed (bubbled) through a liquid, where it may dissolve or react with the liquid

Distilled water is used for readily soluble gases

Principles followed by collectors during data collectionAdsorption: Frequently used Solid adsorption media are

Activated carbon

Silica gel

Sieves

Tenax-GC, Tenax-TA

XAD-2, XAD-4

Chromosorb 101, 102 and 103 etc.

Principles followed by collectors during data collection

Adsorption

The key factors for successful use of these adsorbents are:

Cleaning of the sorbent tube to remove background contamination by

Heating to high temperatures in vacuum

Flowing small quantity of inert gas

Accurate determination of the sampling rate

Analytical methods used

Colorimetric and spectrometric methods are used to quantify a pollutant

Colorimetric method is commonly used for measurement of Formaldehyde

A method referred to as Acid bleached pararosaniline method:

Equivalent to the chromo tropic acid method

Twice as sensitive

Most commonly used detectors for analysis

Thermal conductivity detector (TCD)

Suitable inorganic gases as it measures changes in thermal conductivity

Hot wire detector (HWD)

Measures thermal conductivity and is also suitable for inorganic gases

Flame Ionization Detector (FID)

Detects difference in flame ionization due to combustion suitable for:

Aliphatic compounds

Aromatic compounds

Most commonly used detectors for analysis

Electron Capture Detector (ECD)

Measures the current flow between the electrodes and is suitable for chlorinated hydrocarbons

Flame Photometric Detector (FPD)

Measures light from excited state of Sulphur and Phosphorous compounds in hydrogen flame

Mass Selective Detector (MSD)

It is suitable for most indoor pollutants

This method provides quantitative analysis, and

Identifies different chemicals in a mixture

Source control

Selection of the products that emit very less VOCs

Concentration due to selected building materials should be below 0.05 ppm

Substitution of the material with a material of similar properties having low emission rates

Avoiding the materials containing formaldehyde (like UFFI, Ammonium Sulphite)

Suggested Emission rates of products in building

Materials Emission rates

Flooring material 0.6

Floor coating 0.6

Wall material 0.4

Wall coating 0.4

Movable partitions 0.4

Office furniture 0.25 mg/h/workstation

Office machines (central) 0.25 mg/h/m3 of space

Ozone emission 0.01 mg/h/m3 of space

Office machines (personal) 2.5 mg/h/workstation

Ozone emission 0.1 mg/h/work station

(Source : Tucker, 1990.)

VentilationTypes of ventilation

Infiltration of outdoor air

One of the common cost effective methods

Ineffective if outside air or the in filtered air is itself polluted

Natural ventilation

This happens when all the doors and windows are properly opened

This is the most effective method as there is constant air inflow

The only disadvantage is the increase in the heating or cooling costs

Ventilation

Mechanical ventilation

Use of HVAC system (normally suitable for non-residential places)

Advantageous over other types of ventilation

Energy for heating or cooling can be recovered from the exhaust air

Local Ventilation

This method produces a low pressure around the source using a blower fan

This method is a disadvantage if the source is of continuous type

Air CleaningRemoval by Catalytic Converters

Pollutants found in the air can be converted to less harmful gas using the catalytic converters

Some catalysts used to remove Formaldehyde are:

Purafil

Activated carbon

Alumina oxide

Ammonia fumigation is the method employed for formaldehyde removal (particularly for mobile homes)

Air Cleaning

Removal by absorption

Used for organic pollutant removal from indoor air

Experiments showed removal of formaldehyde up to 63% (but were not tested practically)

Removal by adsorption

Gases are attracted on to the solid and they remain until reversed by applying vacuum or heat

Efficiency of adsorbant should be known before using a activated solid material for a particular pollutant