Environmental Pollution -Especially Air Pollution - and Public Health
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AU J.T. 10(1): 29-37 (Jul. 2006)
Environmental Pollution -Especially Air Pollution - and Public Health
Sr. Little Flower
Department of General Education, Faculty of Arts, Assumption University
Bangkok, Thailand
Abstract
Pollution is a necessary evil of all development. It is an undesirable change in the
physical, chemical or biological characteristics of air, water and soil that may harmfully
affect the life or create a potential health hazard of any living organism and in
particular for man. Industrialized countries of the world release in to the atmosphere
pesticides, detergents, plastics, solvents, fuels, paints, dyes, food additives etc. are some
of the examples. Besides these there are a number of industrial effluents emissions of
poisonous gases in the atmosphere. Mining activities also added to this problem,
particularly as solid waste. The unfavorable conditions created by man himself
threatened the survival not only of man himself but also other living organisms.
Keywords: Pollutant, poisonous gases, industrial effluents, atmosphere, global
warming, environment, green house effect, natural resource, chemicals.
Environment on 14 June 1972 in Stockholm,
Introduction Sweden, the late Prime Minister of India, Indira
The ‘mad rat race’ among nations over Gandhi had said, “Modern man must re-establish
the globe for development jeopardized the an unbroken link with nature and with life. He
heath of man itself. Progress in agriculture and must again learn to invoke the energy for grow-
industry is taken a general criterion of ing things and to recognize, as did the ancients
development of any country. This craze in India centuries ago, that one can take from
resulted into unlimited exploitation of every bit the earth and the atmosphere only so much as
of natural resource. Such activities of man had one put back in the them” (Sharma1998).
adverse effect on all forms of living organisms Pollution is an undesirable change in the
in the biosphere. Unlimited exploitation of physical, chemical or biological characteristics
nature by man disturbed the ecological balance of air, water and soil that may harmfully affect
between living and non living component of the life or create a potential health hazard of
the biosphere. Due to lack of development of a any living organism and in particular for man.
culture of pollution control, there has resulted a What are pollutants? Any substance that
heavy backlog of gaseous, liquid and solid caused pollution is called a pollutant. A
pollution in all over the world. It is to be pollutant may thus include any chemical or
cleaned. Thus pollution control is a recent agrochemical substance, biotic component or
environmental concern. its products or physical factor (heat) that is
The developed countries have been in a released by man into the environment, that may
mad race to exploit every bit of natural have adverse harmful or unpleasant effects. A
resource to convert them into goods for their pollutant has also been defined as any solid,
comfort, and to export them to needy liquid, or gaseous substance present in such
developing world. In doing so, the concentration as may be or tend to be injurious
industrialized countries dump lot of materials to the environment”. Pollutants are the
in their environment which become polluted. residues of things we make, use and throw
In a way, pollution has been ‘exported’ away. There are many sources of such
to developing countries. UN Conference on pollutants. The lake and rivers are polluted by
wastes from chemical and other factories,waste from human and the air by gases of are produced mostly by metallurgical
automobile exhausts, industries, thermal power processes, automobiles, sea spray, etc.
plants, etc. 8. Photochemical products: These are
photochemical smog, PAN, PB2N, etc.
Air Pollution released by automobiles.
9. Particulate matter: These are fly ash,
The atmosphere is an insulating blanket dust, grit and other suspended particulate
around the earth. It is source of essential gases, matter released from power plants and
maintains a narrow difference of day and night industries (stone crushers)
temperatures and provides a medium for long 10. Biological particulate matters: Bacterial
distance radio communication. It also acts as cells, fungal spores and pollens in air.
shield around the earth against lethal UV 11. Toxicants other than heavy metals: These
radiations. With out atmosphere, there will be are complex chemical substances released
no lightening, no wind, no clouds, no rains, no during manufacture of other goods.
snow and no fire.
Carbon Compounds
Sources and Pollutants
The two important pollutants are CO2 and CO.
Air pollution results mainly from
gaseous emissions of industry thermal power Carbon Dioxide (CO2): Major amount of
stations, automobiles, domestic combustions, CO2 is released in the atmosphere from burning
smoke from the fire etc. From the different of fossil fuel (coal, oil, etc.) for domestic
sources of air pollution, a variety of pollutants cooking, heating, etc. and the fuel consumed in
are released in to atmosphere. The main air furnaces of power plants, industries, hot mix
pollutants emitted from these different sources plants, etc. Another reason is the destruction of
and how these pollutants affect the human and the forest in the tropical regions of the world.
other living organisms on the planet are These ecosystems are efficient in removing
described: CO2 and storing the C atoms in the structure of
1. Carbon compounds: These are CO2 and the plant. From fossil fuels alone more than 18
Co, the former is released by complete x 102 ton of CO2 are being released into
combustion of fossil fuels, and the latter atmosphere each year. This gas is also emitted
by automobile exhausts. during volcanic eruptions. An increase in CO2
2. Sulfur compounds: These include SO2, concentration in atmosphere may result into
HS and H2SO4 mostly released by fossil- disastrous effects as green house effect.
fuel-based power generating plants,
thermal plants, and refineries. Greenhouse Effect and Global Warming:
3. Nitrogen oxides: These include NO, NO2, Since CO2 is confined exclusively to the
HNO3 mostly released by automobiles, troposphere, its higher concentration may act a
power plants and industries. serious pollutant. Under normal conditions the
4. Ozone: Its level may rise in astrosphere temperature at the surface of the earth is
due to human activities. maintained by the energy balance of the sun
5. Fluorides: These come from industries, rays that strike the planet and heat that is
insecticides spray etc. reradiated back in to space. However, when
6. Hydrocarbons: These are chiefly benzene, there is an increase in CO2 concentration, the
benz pyrene etc which are released by thick layer of this gas prevents the heat from
automobiles and industries. being reradiated out. This thick CO2 layer thus
7. Metals: These include lead, nickel arsenic, functions like the glass panels of a greenhouse
beryllium, tin, vanadium, titanium, (or the glass windows of a motorcar), allowing
cadmium, etc. present in the air as solid the sunlight to filter through but preventing the
particles or liquid droplets or gases. They heat from being radiated in outer space. This is
the so-called Greenhouse Effect.
30Thus, most heat is absorbed by CO2 layer Inter-governmental Panel on Climate Change
and water vapor in the atmosphere, which adds (IPCC) to study the issue and make
to the heat that is already present. The net recommendations. Its first assessment was
result is the heating up of the earth’s published in 1990. In 1996, the IPCC
atmosphere. Thus increasing CO2 levels tends published its second assessment and concluded
to warm the air in the lower layers of that climate change is occurring and that it is
atmosphere on a global scale. Nearly 100 years highly probable that human activity is an
age the CO2 level was 275 ppm. Today it is important cause of the change. The UNEP had
350 ppm and by the year 2035 and 2040 it is appropriately chosen the slogan “Global
expected to reach 450 ppm. CO2 increases the Warming” to alter the people on World
earth temperature by 50% while CFCs are Environment Day - June 5, 1989. The
responsible for another 20% increase. There problem is that most vulnerable areas in the
are enough (CFCs up there to last 120 years) developing world do not have economic
(Sharma 1999). resources. The hardest hit may be developing
The excess CO2 to some extent is world, which discharge two fifths the of the
absorbed by the oceans. But with the global carbon emissions each year. The effect
industrialization of the west and increased of global warming will be worsening human
consumption of energy, CO2 was released in to health, rising sea level, disruptive of water
the atmosphere at a faster rate than the capacity cycle, changing forest and natural areas and
of oceans to absorb it. Thus its concentration challenges to agriculture and food supply
increased. There are other gases also which (Smith 2000).
contributed to green house effect. These are Carbon Monoxide (CO): The chief source
SO2, NOx, CFCs discharged by industry and are automobiles, though other involving a
agriculture. CFCs were widely used as combustion process as stoves, furnaces, open
refrigerant gases in refrigeration’s and air fires, forest and bush fires, burning coal mines,
conditioners. There is a strong correlation factories, power plants etc also give off co.
between the increase in temperature and the The principal source of this pollutant is the
amount of green house gases. exhaust product from motor vehicles in
According to one projection, changes common busy routes. Natural sources of this
will be the least in the tropics, and the most at gas are various plants and animals. Higher
the poles. So Greenland, Iceland, Norway, animals produce some CO from hemoglobin
Sweden, Finland, Siberia and Alaska will be break down. Some CO is also liberated from
among the most affected. The polar icecaps bile Juice. Break down of photosynthetic
would melt. The floating Western Antarctica pigments in algae also release some CO. The
ice sheet could begin to melt. A rise of five smoke of automobiles and thermal power and
degrees would raise the sea level by five meters hot mix plants, stone crushers etc also
within a few decades, threatening all the contribute to CO. level in air.
densely populated coastal cities from Shanghai In the USA in 1965, 66 million tons of
to San Francisco. CO. was emitted by automobile exhaust,
According to an estimate, if all the ice on roughly 91% of this gas from all sources. In
earth should melt 200 feet of water would be Los Angels in 1971, the CO. emission from
added to surface of all oceans, and low lying automobiles was 8,960 tons daily and
coastal cities as Bangkok and Venice Would be comprised 98% of CO. from all sources. In the
inundated. Due to green house effect, there air, its concentration is from traces to 0.5 ppm
may occur more hurricanes and Ceylonese and (Sharma1999)
early snow melts in mountains causing more CO is harmful to those persons exposed
floods during monsoon. to congested high ways. Thus drivers are the
During the 1980s, scientists, governments, most affected people. CO causes difficulty in
and the public became concerned about the breathing, causes headache, and irritation-1 of
possibility that the world may be getting mucous membranes. It combines with
warmer. UNEP, for exmple, established the hemoglobin of blood, reducing its O2 –
31carrying capacity. (cigarette smokers have readily passes through alveolar membrane of
increased hematocrit (per cent volume of red the lung and penetrates the blood stream. Death
blood cells), Within minutes of smoking. In occurs due to respiratory failures.
developed countries cigarettes are linked to at
least 80% of all death from lung cancer. Nitrogen Oxides (NOx)
Sulfur Dioxide Even in unpolluted atmosphere, there are
present measurable amounts of nitrous oxide,
The major source of SO2 emission is nitric oxide and nitrogen dioxide. Of these,
burning of fossil fuels in thermal Power plants, nitric oxide (NO) is the pivot compound. It is
smelting industries, and other process as produced by combustion of O2 and N2 during
manufacture of sulfuric acid and fertilizers. lightning discharges and by bacterial oxidation
These account for about 75% of the total SO2 of NH3 to form poisonous NO2. NO2 may react
emission. The rest 25% emission is from with water vapor in air to form HNO3. This
automobiles and petroleum refineries. In acid combines with NH3 to form ammonium
U.S.A in 1970 there was emitted 37 million nitrate. About 95% of the NOx is emitted as
tons of SO2, which is likely to go up to 95 NO and remaining 5% as NO2. In metropolitan
million tons by 1990. It is believed that about cities, vehicular exhaust is the most important
109 million tons SO2 are added each year in to source of nitrogen oxides.
the global environment.
SO2 causes intense irritation to eyes and Nitrous Oxide (N2O): This gas has so far
respiratory tract. It is absorbed in the moist not been implicated in air pollution.
passage of upper respiratory tract, leading to Nitric Oxide (NO): The chief source of this
swelling and stimulated mucus secretion. gas is the industries manufacturing HNO3 and
This gas causes damage to higher plants, other chemicals, and the automobile exhausts.
forming necrotic areas on leaf. In most plants Nitric oxide, is responsible for several
leaf are collapses under intense exposure to photochemical reactions in the atmosphere, in
SO2. SO2 is also involved in the erosion of the formation of pollutants like PAN, O3,
building materials as limestone Marble, the carbonyl compounds etc. in the presence of
slate use in roofing, mortar and deterioration of other organic substances. There is little
statues. Petroleum refineries, Smelters, Kraft evidence o the direct role of this gas is causing
paper mills deteriorate the adjoining historic a health hazard, at the levels found in urban air.
movements.
Nitrogen Dioxide (NO2): A deep reddish
Hydrogen Sulphide brown gas, which is the only widely prevalent
colored pollutant gas. This gas is the chief
The chief source of H2S is decaying constituent of photo chemical smog. NO2
vegetation and animal matter, especially in causes irritation of alveoli, leading to
aquatic habitats. Sulfur springs, volcanic symptoms resembling emphysema. Lung
eruptions, coal pits and sewers also give of this inflammation may be followed by edema and
gas. About 30 million tons of H2S every year final death.
is released by oceans and 60 to 80 million tons
per year by land. Industries emit 3 million ton Acid Rains
5 every year. The chief industrial sources of
H2S are, users of sulfur containing fuels. Oxides of sulfur and nitrogen are
At low concentration H2S causes important gaseous pollutants of air. These
headaches, nausea, collapse, coma and final oxides can travel thousands of Kilometers in
death. Un pleasant odor may destroy the appetite the atmosphere. They stay in the atmosphere
at 5 ppm level in some people. A concentration and are to be oxidized in to acids. Sulfuric and
of 150 ppm may cause conjunctivitis and Nitric acids are the main acids, which dissolve
irritation of mucus membranes. This gas in the water in the atmosphere and fall to the
32ground as acid rain or may remain in the in industrialized areas causing several un
atmosphere in clouds and fogs. pleasant effects. The stratosphere could be
The acid rain problem has increased due regarded as a sink, but unfortunately, these
to industrialization. Burning of fossil fuels for pollutants (CFCs) react with the ozone and
power generation contributes to almost 60 – deplete it.
70% of total SO2 emitted globally. Emission The ozone near the earth’s surface in the
of NOx from human activity ranges between 20 troposphere creates pollution problems. Ozone
- 90 million tons annually over the globe. and peroxy acetyl nitrate (PAN) and hydrogen
Acid rains are a great threat to British peroxide are formed by the reaction between
environment as to central Europe and Southern NO2 and hydro carbon in sunlight. These
Scandinavia. In 1974 acid rains over Scotland pollutants cause photo chemical smog. Higher
were found to be sourer than vinegar (pH 2.4). levels of O3 in the atmosphere protect us, and is
Much of the falling snow in Britain is now harmful when it comes in direct contact with us
highly acidic.(Smith 2000) If it does not melt and plants at earth’s surface.
it may turn in to a pollution time bomb. Heavy Any depletion of ozone, have catastrophic
winds pick up acid rain from factories in effects on life systems of the earth. Major
Britain and Frances to Sweden. Ninety percent pollutants responsible for this depletion are
of acid rains of Norway and 75% of Sweden chlorofluoro carbons, nitrogen oxides and
are due to drifted acid rain oxides. It is a major hydrocarbons. CFCs are used as coolants in air
political issue. conditioners and refrigerators, cleaning
Acid rains create complex problems and solvents, aerosol propellants and in foam
their impacts are far reaching. They increase insulation. They escape as aerosol in the
soil acidity, this affecting land flora and fauna; stratosphere. The threat to O3 is mainly from
cause acidification of lakes and streams thus CFCs. Depletion of O3 cause temperature
affecting aquatic life, affects crop productivity changes on the earth.
and human health. Besides these they also Cancer is the best established threat to
corrode buildings, monuments, bridges, fences, man, especially relating to skin like melanoma.
railing, etc. The other disorders are cataracts, destruction of
aquatic life and vegetation and loss of
immunity. Nearly 6,000 people die of such
Ozone (O3)
cancers in USA each year.
There are also indirect effects. If the
Ozone layer in the stratosphere protects
plants exposed the UV radiation showed
us from the harmful UV radiation from Sun.
reduction in chlorophyll content, reduction in
The depletion of this O3 layer by human
growth and increase in harmful mutations.
activities may have serious implications and
this has become a subject of much concern Global efforts: The first global conference
over the last few years. Ozone is also formed on the depletion of ozone layer was held in
in the atmosphere through chemical reactions. Vienna (Austria) in 1985, the year, scientists
The atmospheric ozone is now being regarded discovered hole in south pole. British team
as potential danger to human health and crop discovered a hole in ozone layer as large as that
growth. of the United States. This was followed by
The ozone layer has two important and Montreal Protocol in 1987 which called for a
interrelated effects. It absorbs UV light and 50% cut in the use of CFCs by 1998 reducing
thus protects all life on earth from harmful to the level of 1986, 95% of CFCs is released
effects of radiation. By absorbing the UV by European countries, USA, USSR, and
radiation the ozone layer heats the stratosphere, Japan. The three-day international “Saving the
causing temperature inversion. It limits the ozone layer” conference was organized jointly
vertical mixing of pollutants, there by causing in London in March 1989 by the British
the dispersal of pollutants over large areas and government and the UNEP.
near the earth’s surface. That is why a thick There was another international
cloud of pollutants hangs over the atmosphere conference on ozone at Helsinki in may 1989
33to revise the Montreal Protocol. As many as 80 concentration may cause explosions. At high
nations agreed to have a total ban on chemicals levels in absence of oxygen, methane may be
that cause ozone depletion by 2,000 A.D. The narcotic on man.
agreement for CFC elimination by 2,000 AD is
needed as a major step towards environmental Metals
protection(.P.D.Sharma1999)
In air, the common metals present are
Fluorides mercury, lead, zinc and cadmium. They are
released from industries and human activities
Fluorides in atmosphere come from in the atmosphere.
industrial process of phosphate fertilizers, Mercury: Mercury is a liquid volatile metal
ceramics, aluminum, fluorinated hydrocarbons, (found in rock and soil) is present in air, as a
uranium and other metals. The pollutant is in result of human activities. Human use mercury
gaseous or particulate state. In air fluoride compounds in production of fungicides, paints,
chiefly comes from smoke of industries, cosmetics, paper pulp etc. By inhalation
volcanic eruptions, and insecticide sprays. In nervous system, liver, eyes are damaged.
plants it causes tip burn. Fluoride pollution in Infant may be deformed. Other symptoms are
man and animals is mainly through water. In headache, fatigue, anxiety, loss of appetite etc.
minute amounts, fluorides are beneficial
helping prevention of tooth-decay in man. Lead: Lead is added to gasoline to reduce
However, higher levels become toxic. Knocking are emitted in to the air with the
exhaust as volatile lead halides (bromides &
chloride) About 75% of lead burnt in gasoline
Hydrocarbons comes out as lead halides through tail pipe in
exhaust gases. Of this 40% settles an the
Among the hydrocarbons the chief air ground 60% gels in to air. Lead inhalation
pollutants are benzene, benzepyrene, and causes reduced hemoglobin formation, thus
methane. The Motor vehicles are their chief leading to anemia. It also damage RBCs
source. These are emitted by evaporation of resulting in infections of liver & kidney in
gasoline through carburetors, crankcase etc. man.
They have carcinogenic effects on lung.
They combine with NOx under UV component Zinc: Zinc in air occurs mostly as white zinc
of light to form other pollutants like PAN and oxide fumes & is toxic to man.
O3 which cause irritation of eye, nose, throat Cadmium: It occurs in air due to industries.
and respiratory distress. Industries engage in extraction, refining,
electroplating and welding of cadmium
Benzene containing materials and refining of copper,
lead and zinc are the major source of cadmium
It is a liquid pollutant emitted from in air. This metal is emitted as vapor, it
gasoline. It causes lung cancer. Benzepyrene is quickly reacts to form oxide, sulfate, or
most potent cancer inducing hydrocarbon chloride compounds. It is poisonous and
pollutant. It is also present in small amounts in accumulates in human liver and kidney. It
smoke, tobacco, charcoal boiled stakes and causes hypertension, emphysema and kidney
gasoline exhaust. damage.
Methane Photochemical Products
Methane is a gaseous pollutant, in NOx, hydrocarbons and O3 in the
minute quantity in air. In nature it is produced atmosphere are air pollutants. These may react
during decay of garbage, aquatic vegetation with each other the presence of sunlight,
etc. This is also released due to burning of producing secondary pollutants in the air. The
natural gas and from factories. Higher main photochemical products are olefins,
34aldehydes, ozone, PAN, PB2N and textiles, pesticides, fertilizers and chemical
photochemical smog. production), industrial fugitive process
(loading and transfer operations) non industrial
Olefines: Olefines are produced directly
fugitive process (road way dust, agricultural
from exhaust and in the atmosphere from
operations, construction, fire etc.) vehicles
ethylene. They affect plants, especially they
exhaust, clutch and break wear.
wither sepals of orchid flowers, retard the
Particulate matter is injurious to health.
opening of carnation flowers & also high level
Soot, lead particles, asbestos, flash, volcanic
retard the growth of tomatoes.
emission, pesticides, H2SO4 mist, metallic dust,
Among the photochemical products,
cotton and cement dust, etc. when inhaled by
benzepyrene, PAN, and peroxy benzoil nitrate
man cause respiratory diseases such as
(PB2N) are the most potent pollutants.
Benzepyrene is carcinogenic. PAN is an eye tuberculosis and cancer.
In addition there are many kinds of
irritant. PAN and O3 cause respiratory distress.
biological particulate matter that suspended in
Photochemical Smog: It is produced as atmosphere. These are bacterial cells, spores,
a result of photochemical reaction among NOx, pollen grains, and fungal spores. These cause
hydrocarbons and oxygen. Photochemical allergy, bronchial disorders and any other
smog formation occurred only during night or diseases in man animals & plants.
cloudy days. Smog is formed by the
combination of smoke and Fog which Hazardous and Toxic Substances
characterized air pollution episode in
London, Glasgow, Manchester and other Hazardous substances are those that can
cities of U.K where sulfur rich coal was used. cause harm to humans or the environment. The
The U.K smog was a mixture of reducing U.S. Environmental protection Agency (EPA)
pollutants and has been called reducing smog, defines hazardous materials have one or more
where as Los Angeles smog a mixture of of the following characteristics.
oxidizing pollutants is called oxidizing smog 1. Ignitability – substances that catch fire
which is produced as a result of pollution by readily (e.g. gasoline and alcohol).
domestic fires and exhaust from motor 2. Corrosivity – substances that corrode
vehicles. storage tanks and equipment (e.g. acid).
Photochemical smog adversely affects 3. Reactivity – substances that are
plants, human health and Materials. The chemically unstable and may explode or
oxidants enter as part of inhaled air, interfere create toxic fumes when mixed with
with respiratory process causing asthma and water. (eg. conc. H2SO4).
bronchitis in epidemic form. Another serious 4. Toxicity – substances that are injurious to
disease is emphysema. health when in hailed e.g. chlorine,
The smoke, fog, mist, dust, soot etc in ammonia, pesticides and formaldehyde.
the smog reduce the visibility, damage crop, Toxic substances are poisonous and cause
and cause corrosion of metals, stones, building death or serious injury to humans and other
materials, painted surfaces, paper, leather etc. organisms. They are: (i) heavy metals, and
Particulate Matter: This is a discrete mass (ii) non-biodegradable synthetic organics.
of any material, except pure water, that exist as
solid or liquid in atmosphere and of Heavy Metals
microscopic or submicroscopic dimensions. It
arises in atmosphere from natural as well as The most dangerous heavy metals are
man made sources. Natural sources are soil lead, mercury, arsenic, cadmium, tin,
and rock debris (dust) volcanic emission, forest chromium, zinc and copper. These metals are
fires and reaction between natural gas widely used in industry particularly in metal
emissions. working or metal plating shops, and in such
Human activities are industrial products as batteries and electronics. They are
operations (mining, smelting, polishing, also used in pesticides and medicines, used in
35paints pigments glazes, inks and dyes. Thus Bio-accumulation and Bio-magnification
heavy metals may enter the environment
wherever any of these products are produced, Heavy metals and non-biodegradable
used and ultimately discarded. synthetic organic compounds are accumulated
Heavy metals are toxic because, as ions in the organisms. Because of accumulation in
or in certain compounds, they are soluble in small amounts received over a long period of
water and may be readily absorbed in to the time may reach to toxic levels. This
body, where they combine with and inhibit the phenomenon is referred to as bio-accumulation
functioning of particular vital enzymes. Even (Nebel 1998).
very small amounts can have physiological or Organisms act as filter for heavy metals
neurological consequences. and synthetic organics. Heavy metals are
The mental retardation caused by lead removed from solution. Synthetic organics are
poisoning and crippling birth defects caused by highly soluble in lipids (fats and fatty
mercury are well known examples. compounds) but sparingly soluble in water. As
they pass through cell membranes, which are
Non-biodegradable Synthetic Organic lipid, they come out of water solution and enter
Compounds in to the lipid of the body. Thus traces of
heavy metals and synthetic organics that are
Synthetic organic compounds are absorbed by the water and water soluble wastes
plastics, synthetic fibers, synthetic rubber, are passed in the urine. Since the body has no
modern paint like coatings, solvents, pesticides, mechanism to excrete the heavy metals and
wood preservatives and hundreds of other synthetic organics, trace levels consumed over
products. time gradually accumulate in the body and
These products are toxic because they produce toxic effects.
are absorbed in to the body, there they interact Each organism accumulates the
with the particular enzymes, but their non contamination in its food, so it accumulates in
biodegradability prevents them from being its body. All the contaminants accumulated by
broken down or processed further. The result the higher organism through smaller organism
is that they upset the system. When a person when they consume them as food. This
ingests a high dose, the effect may be an acute multiplying effect of bioaccumulation that
poisoning and death. occurs through the food chain is called bio-
With a low dose over extended periods, magnification. The pesticide D.DT is an
the effects are insidious and can be mutagenic, example of bio-magnification (Nebel 1998).
carcinogenic, or teratogenic (birth defect). There is no warning symptoms in the
They may cause liver and kidney dysfunction, beginning, until the contaminant concentration
sterility and numerous other physiological and in the body are high enough to cause problems.
neurological problems. Then it is too late to do much about.
The troublesome class of synthetic There are also several polycentric
organics is the halogenated hydrocarbons. It is aromatic hydrocarbons. (PAHs), which arrive
organic compounds in which one or more of in the atmosphere from coal production,
the hydrogen atoms have been replaced by vehicle disposal, wood burning, municipal
atoms of chlorine, bromine, fluorine, or iodine. incineration, petroleum refining and coal
These four elements are classed as halogens. furnaces. In general they do not produce
Of the halogenated hydrocarbons, the adverse effect in their parent forms. However
chlorinated hydrocarbons are the most if metabolized by enzymes of the body, they
common. Organic chlorides are used in produce intermediates which are capable of
plastics, pesticides, solvents electrical producing cancer.
insulation, flame retardants and many other
products.
36Prevention and Control of Air Pollution. Conclusion
We have seen that the main sources of air The environment and its relation to
pollution are motor vehicles, industries – humanity is one of the most important
particularly their chimney wastes, and fossil problems of the present time. Environmental
fuel (coal) based plants, as thermal power problems are man made. Hence man naturally
plants. Steps are to be taken to control is the solution to most of them. With his
pollution at source (prevention) as well as after unique technological capabilities he can
the release of pollutants in the atmosphere. increase or decrease human miseries.
Exploitation of nature was considered
Vehicular Pollution inevitable for human survival. Hence man is
obliged to re examine his values, attitudes,
How can we control the air pollution by behavior, life styles and where necessary to
motor vehicles? alter them to ensure his survival. To day we
have both knowledge and technology for a
1. By checking pollutant emission from sound ecological management. We know how
vehicular exhaust. This can be achieved by: to control pollution, how to recycle materials
(i) using gas additives to improve and nutrients and harness solar energy. What is
combustion. required is only a matter of desire and will as
(ii) more exact timing of fuel feeding. individuals and societies to put what is known
(iii) using new proportion of gasoline and in to practice. All powers are given to man to
air. preserve a quality environment. Our
(iv) injecting air to exhaust to convert environmental recession making should reflect
exhaust compounds to less toxic this fundamental purpose of human existence.
materials.
(v) updating of engine design to improve
combustion.
References
(vi) The three pollutant, CO, NOx and
hydrocarbon can eliminate by
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to have devised a simple attachment Interrelationship, 8th ed. McGraw-Hill,
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by motor vehicle. The reactor is fitted Nebel, B.J.; and Wright, R.T. 1998.
to exhaust tailpipe and it converts th
Environmental Science, 6 ed. Prentice
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paper mills, cement factory carbon block plants
etc.
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