™ Organic Air Toxics
(HAZARDOUS AIR POLLUTANTS)
Air toxics are pollutants present in the environment in low concentration (other
than criteria pollutants) that are known, or suspected to be as toxic and
persistent. The term ‘air toxics’ and ‘hazardous air pollutants’ (HAPs) are used
interchangeably. Trace organics belong to the category of air toxics. Most air
toxics originate from human made sources, including mobile sources (e.g. cars,
trucks, buses) and stationary sources (e.g. refineries, petrochemical industries,
pharmaceuticals, dye & dye intermediate, paint & varnish, incineration, power
plants, coke ovens, steel & other metallurgical plants) as well as indoor & nonpoint sources (i.e. use of pesticides & cleaning solvents). HAPs include volatile
organic compounds (including benzene, toluene etc), polycyclic aromatic
hydrocarbons (like benzo(a)pyrene etc), persistent organic pollutants (PCBs,
dioxins & furans and pesticides). Air lab has capabilities of measurement
of these HAPs including VOCs such as benzene, toluene, xylene and
polycyclic aromatic hydrocarbons such as benzo(a)pyrene etc.
PhysioChemical Properties
Volatility, Flammability
Composition, Toxicity
Persistence
Toxicity
Man
Manufacturer
Producer
End user
Animals
Plants
Microorganisms
HAZARDOUS AIR
POLLUTANTS
Dispersion Tendency
Bioaccumulation
Geoaccumulation
Biodegradability
Metabolism
Abiotic Mineralisation
Chemical Transformation
Phototransformation
Handling Risk
Storage
Transport
Processing
Polynuclear Aromatic Hydrocarbons (PAHs) in Air of Urban Atmosphere
The burning of fuels in industrial activities and transportation leads to a plethora of
combustion of products, which contribute towards air pollution including toxic trace
organics like PAHs. PAHs are semi volatile in nature & therefore these can be present in
particulate as well as vapour phase while others are mostly adsorbed onto particles in
the environment. The major compounds are Napthlene, Phenanthrene, Anthracene,
Fluoranthene, Pyrene, Chrysene, Benzo (a) anthracene, Benzo (b)fluoranthene, Benzo
(k)fluoranthene, Benzo (e)pyrene, Benzo (a)pyrene, Perylene, Benzo (ghi)perylene,
Dibenzo(ah) anthracene, Indeno(cd)pyrene, Coronene.
Box
- Major PAH Compounds
Acenaphthylene(C10H8)
Benzo(b) f luoranthene (C20H12)
Acenaphthene(C10H8)
Benzo(k) fluoranthene (C20H12)
Fluorene(C10H8)
Coronene (C24H12)
Naphthalene (C10H8)
Benzo(e) pyrene (C20H12)
Phenanthrene (C14H10)
Benzo(a) pyrene (C20H12)
Anthracene (C14H10)
Perylene (C20H12)
Fluoranthene (C16H10)
Benzo(ghi) perylene (C22H12)
Pyrene (C16H10)
Dibenzo(ah) anthracenes (C22H14)
Chrysene (C18H12)
Indeno(cd) pyrene (C22H12)
Benzo(a) anthracene (C18H12)
Sources of PAHs in the Environment
The sources of PAHs are anthropogenic and natural both as forest fire, volcanic
activities, bacterial decay of materials, coke oven, automobiles, diesel exhaust etc. Major
sources are Combustion of fossil fuels, Automobile engine exhausts, Atmospheric fallout
of fly ash particulate, Coal tar and other coal processing wastes, Aluminum Plants,
Refinery and oil storage wastes, Accidentals spills from oil tankers and other ships,
Tobacco and cigarette smoke, Refuse and waste incineration.
Exposure to PAHs
Box - Exposure to PAHs
Breathing cigarette smoke, auto emissions or industrial exhausts;
people living near such sources (like major highways) or working at
such places (like TPPs).
Drinking groundwater near disposal sites where construction wastes or
ash are buried.
Eating Charcoal-broiled foods, especially meats, Shellfish living in
contaminated water.
Touching - handling contaminated soil or bathing in contaminated
water, using medicated skin cream or shampoo containing PAHs, may
result in absorption through skin.
Health Effects of PAH Exposure
Health Effects of PAH exposure constitutes skin redness, blistering, and peeling.
Chronic exposure may lead to cancer, lung irritation, reproductive effects organ systems
damage (lungs, liver, skin, and kidneys), respiratory problems and behavioral effects.
Some PAHs are classified as potent carcinogens. The benzo (a) pyrene is referred to as
“one of the most potent carcinogens known”.
Volatile Organic Compounds/ BTEX in Urban Air
The organic compounds that evaporate easily are recognized together as volatile
organic compounds. Technically such compounds are defined as organic compounds
with a vapour pressure of 1300 Pascal (about 1% atmospheric pressure at sea level).
These compounds may include several aromatic hydrocarbons and considered into the
common category due to their similar physical behavior in the atmosphere. These
compounds have a boiling point range with lower limit between 50°C and 100°C and an
upper limit between 240°C and 260°C where the higher refer to polar compound.
There are 15 high priorities; 17 medium priorities; and 20 low priority VOCs for India, as
identified by the CPCB.
Emission sources
VOCs emerge as evaporative emissions during handling, storage and use and as part of
unburnt or partially burnt hydrocarbons mostly along with exhaust gases from vehicles.
There are thousands of different VOCs produced and used in our daily lives. Their main
sources are as below.
Petrochemicals, Oil refineries, Pharmaceuticals, Paints, Varnishes, Moth balls, Solvents,
Gasoline, Newspaper, Upholstery, Fabrics, Cooking, Dry Cleaning, Chemicals, Vinyl
floors, Carpets, Photocopying, Sealing, Adhesives, Caulks, Cosmetics, Air Fresheners,
Fuel Oil, Environmental Tobacco Smoke etc.
The volatile organic compounds include several aromatic hydrocarbons but BTEX (i.e.
Benzene, Toluene, Ethyl Benzene o-Xylene, m-Xylene , p-Xylene ) constitute a major
fraction in terms of their presence & quantity in the urban atmosphere.
Box - Mobile Source Air Toxics
Acetaldehyde, Acrolein, Arsenic Compounds, Benzene, 1,3-Butadiene, Chromium
Compounds, Dioxin/Furans, Diesel Particulate Matter + Diesel Exhaust Organic Gases
(DPM + DEOG), Ethylbenzene, Formaldehyde, n–Hexane, Lead Compounds,
Manganese Compounds, Mercury Compounds, MTBE, Naphthalene, Nickel
Compounds, Polycyclic Organic Matter, Styrene, Toluene, Xylene.
Mobile Source generate lot of air toxics including VOCs & BTEX
Health effects
Health effects may comprise of Acute or Chronic effects on human body
Acute - Eye irritation / watering, Nose irritation, Throat irritation, Head-ache,
Nausea/Vomiting, Dizziness, Asthma exacerbation
Chronic - Cancer, Liver damage, Kidney damage, Central Nervous System damage
Instrumental Capabilities
Air toxics lab is equipped with Gas Chromatograph-Mass Spectrometer with Automated
Thermal Desorption, Gas Chromatograph with Flame Ionization Detector & Head Space
and Gas Chromatograph with Sample Pre concentration Trap (SPT) and other sample
processing equipments / apparatuses etc.
GC - MS
Fig: Rotary Evaporator for Concentration of Extracted Organic Samples