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					(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-            Trichloroethylene    Tetrachloroethylene   Benzene
Trichloroethane
o-Xylene          m,p-Xylene           m,p-Dichlorobenzene   Ethylbenzene

Styrene           1,2-Dichloroethane   1,1,1,2-              1,1,2,2-
                                       Tetrachloroethane     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        Dust
 carpets
 General cleaning    Ammonium hydroxide, Lye, Chlorine, Sodium hypochloride
                     etc.
Pollutants associated with various activity levels
Painting/varnishing       Toulene, Xylene, Methyl chloride, Heavy metals, Pigments,
                          Methanol, Ethylene glycol, Benzene
Application of            Organophosphates, Carbamates, Pyrethroids
Pesticides
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     Formaldehyde, VOCs
gassing
   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
1396 residents of UFFI Not reported             Wheezing: e, 60%; ne, 10%;
homes and 1395 of non-                          Burning skin: e, 70%; ne, 10%;
UFFI homes (Thun et
al.,1984)

70 employees in 7       Mobile home: 0.24 –     Menstrual irregularities: e, 35%;
mobile homes and 34     0.55 ppm                ne, none
non-exposed employees   Building: 0.05 – 0.11   Eye irritation: e, 55%, ne,15%;
in 3 buildings          ppm                     Headache: e,80%; ne, 22%;

21 workers in mobile    Mobile home: 0.12 –     Eye irritation: e, 81%; ne, 17%;
homes and 18 workers    0.16 ppm                Throat irritation: e, 57%; ne, 22%;
in buildings            Building: not           Fatigue: e,81%; ne, 22%;
                        reported                Headache: e, 76%; ne, 11%;

                                                Where: e – Exposed and
                                                       ne – Non-exposed.
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
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 Hydrocarbons
 Pollutants                                   (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                                    B, suspected
 A2 animal                                    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 Furnishings
         medium    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      Floor covering (rugs, linoleum, varnishes, plastics),
resisters and water     carpet backings, adhesive binders, fire retardants,
repellents              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                     Summer
   Combustion             No. of    Mean      Std.    No. of   Mean     Std.
   sources                homes     (ppm)     Dev.    homes    (ppm)    Dev.
   None                   31        0.046     0.035   34       0.059    0.043
   Woodstove              63        0.053     0.032   62       0.082    0.038
   Kerosene heater        39        0.055     0.028   42       0.067    0.033
   Kerosene heater        17        0.05      0.026   13       0.075    0.032
   and woodstove
   Smoker                 33        0.046     0.025   25       0.055    0.031
   Smoker and             41        0.048     0.024   39       0.068    0.032
   woodstove
   Smoker and             32        0.042     0.018   32       0.054    0.026
   kerosene heater
   Smoker,                25        0.047     0.027   22       0.06     0.025
   woodstove and
   kerosene heater
    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)
Emissions of Organic Chemicals from Household Products
                                   Emission (in ppm)
     Compound          Adhesives   Coatings   Fabrics   Foam   Lubricants
   1,2-
                          0.8                           0.75
   Dichloroethane
      Benzene             0.9        0.6                0.7       0.2
    Carbon
                         1.00                           0.18
    tetrachloride
     Chloroform          0.15                  0.10     0.04     0.20
    Ethyl benzene
      Limonene
 Methyl chloroform        0.4        0.2       0.07     1.00     0.50
       Styrene           0.17        5.20               0.02     12.54
  Tetrachloroethylen
                         0.60                  0.30     65.0     0.10
  e
  Trichloroethylene      0.30        0.09      0.03     0.10     0.10
Emission of Organic Chemicals from Household Products
                               Emission   in ppm
    Compound          Paints   Rubber     Tape     Cosmetics   deodorants
1,2-Dichloroethane                        3.25
     Benzene           0.90      0.10     0.69
   Carbon
                                 4.20     0.75
   tetrachloride
    Chloroform                   0.90     0.05
  Ethyl benzene       527.80              0.20
    Limonene                                                      0.40
Methyl chloroform                0.10     0.10       0.20
     Styrene          33.50      0.15     0.10       1.10         0.15
Tetrachloroethylene              0.20     0.08       0.70
 Trichloroethylene               0.07     0.09       1.90
Emission of Organic Chemicals from Household Products
                                      Emission      (in ppm)
                        Health &      Electrical   Misc. house
      Compound                                                   Ink pens
                        beauty aids   equipment    wares
  1,2-Dichloroethane                    0.06
       Benzene             1.85         0.02          1.10        0.40

 Carbon tetrachloride                   0.00          0.04        0.20

     Chloroform                         0.23          4.85        10.00
    Ethyl benzene                       0.80
      Limonene             1.00                       1.80
  Methyl chloroform        0.01         0.03          0.19        0.10
       Styrene             0.17         0.05          0.02        0.30
  Tetrachloroethylene                   0.05                      2.00
   Trichloroethylene       0.11         0.01          0.06        0.07
Emission of Organic Chemicals from Household Products
                                                   Emission (ppm)
                                                                        Photo
       Compound                  Paper equipment     Photo film
                                                                      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
       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 humans
                                                   Emission rate
Organic compounds    Typical conc.(389 people in   Lecture class        During examination
                     class (ppb))                  225 people
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
collection
  Adsorption: 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.)
Ventilation
 Types 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 Cleaning
Removal 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

				
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