AIR POLLUTION SOURCES 79
Part 1. Pollutant Emissions (continued)Pollutant types Sources and abundance Abatement and control- it contributes to photochemically produced air
pollution. Ethylene is the most abundant (based on
mole volume) of the photoreactive hydrocarbons in
the lower atmosphere.
In the chemical process industry, virtually all
ethylene is consumed as feedstock for a
variety of petrochemical products. Ethylene
has been known to be used as a ripening
agent for fruits and vegetables- Organic Carcinogens: These are carbon compounds
which cause cancer in experimental animals and are
therefore suspected of playing a role in causing
human cancer, particularly cancer of the lungs. There
is some question as to the carcinogenicity of selected
compounds. Polynuclear aromatic hydrocarbons
(PAH) in our environment evolve from high-
temperature reactions under pyrolytic conditions
during incomplete combustion contained in some air
pollution source effluents in automobile exhaust
fumes, and in moderate concentrations in the air. The
major classes of organic carcinogens are as follows: - Polynuclear aromatic hydrocarbons (PAH);
Benzo-(a)-pyrene (BAP)-substance found in
cigarette smoke.
Benzo(e)pyrene
Benzo(a)anthracene
Benzo(e)acetophenthrylene
Benzo(b)fluoranthene
Chrysene - Polynuclear azo-heterocyclic compounds;
Dibenz(a,h)acridine
Dibenz(a,j)acrydine - Polynuclear imino-heterocyclic compounds
- Polynuclear carbonyl compounds
7H-Benz(de)anthracene-7-one - Alkylation agents
Aliphatic and alifinic epoxides
Peroxide
Bactones
The incomplete combustion of matter containing
carbon. Heat generation (burning coal, oil and
gas) accounts for more than 85%. Sources of
heat generation that were tested ranged in size
from residential heaters to heavy industrial
power plant boilers. Municipal incinerators
produce about 5% of emissions. Industrial
processes also account for 5%.
Organic carcinogens are primarily unwanted
by-products of incomplete combustion.
However, a few sources of organic carcinogens
might be defined as naturally occurring.
Bituminous coal contains certain organic
carcinogens.From Motor Vehicle Sources: (Same
Controls as Hydrocarbons)
From Stationary Sources:- Design equipment to use or
consume completely the processed
material. - Use of materials which have a
higher boiling point or are less
photochemically reactive. - Use of control equipment to reduce
emissions. - Stop open burning of waste by use
of multiple-chamber incinerators or
disposing of waste in sanitary
landfills. - Halogenated Hydrocarbons: Halogenated
hydrocarbons are carbon and hydrogen compounds
with one or more of the halide elements of fluorine,
chlorine, bromine, or iodine. Of these elements, the
most common halogenated hydrocarbons are those
containing fluorine and chlorine.
Halogenated hydrocarbons were once thought to solve
the ozone problem because of their low reactivity.
However, many of these compounds are very toxic and
thus cause a more immediate threat to human health.
Also, there is a great concern of damage caused by
these compounds to the stratospheric ozone layer
which protects us from the harmful ultraviolet
radiation of the sun. These compounds tend to degrade
into their elemental components, which include radical
alogen, which have a great affinity for ozone.
Halogenated hydrocarbon solvent vapors
include those of chloroform (CHCl 3 ), carbon
tetrachloride (CCl 4 ), trichloroethylene
(C 2 HCl 3 ), perchloroethylene (C 2 Cl 4 ), etc.
From vapors (CFCl 3 , C 3 FCl 3 ) are very widely
used as refrigerants and were once used as
propellants. Except for the vicinity of major
urban areas, atmospheric halogen
concentrations are very low.The same controls apply for
halogenated hydrocarbons as for
non-halogenated hydrocarbons.
These are adsorption, absorption,
etc. However, combustion may be
undesirable since free halogen
radical combining with water vapor
may cause an acid problem. This
may damage equipment as well as
create a serious environmental
problem.- Pesticides: Pesticides are economic poisons used to
control or destroy pests that cause economic losses or
adverse human health effects. These chemicals can be
grouped as insecticides, herbicides (weed and brush
killers, defoliants, and desiccants), fungicides,
iscaricides, nematocides, repellants, attractants, and
plant growth regulators.
In the United States, 300–400 pesticides are registered
for use in the production of food. These chemicals
The primary source of pesticides in air is from the
application process; a certain amount of drift is
unavoidable, even under normal conditions.
Pesticides can evaporate into the air from soil,
water and treated surfaces. Pesticides contained
in dust from the soil can enter the air and be
transported for considerable distances before
falling back to the earth. Chemical plants
manufacturing pesticides also produce
pollutant emissions.Improved application equipment and
methods:
Improved formulas for pesticides (higher
density or use water soluble oils)
Wider distribution and use of weather
data in area where pesticides are
used.(continued)C001_006_r03.indd 79C001_006_r03.indd 79 11/23/2005 9:42:37 AM11/23/2005 9: