Environmental Pollution and Public health - AU Journal

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
the globe for development jeopardized the
heath of man itself. Progress in agriculture and
industry is taken a general criterion of
development of any country. This craze
resulted into unlimited exploitation of every bit
of natural resource. Such activities of man had
adverse effect on all forms of living organisms
in the biosphere. Unlimited exploitation of
nature by man disturbed the ecological balance
between living and non living component of
the biosphere. Due to lack of development of a
culture of pollution control, there has resulted a
heavy backlog of gaseous, liquid and solid
pollution in all over the world. It is to be
cleaned. Thus pollution control is a recent
environmental concern.
The developed countries have been in a
mad race to exploit every bit of natural
resource to convert them into goods for their
comfort, and to export them to needy
developing world. In doing so, the
industrialized countries dump lot of materials
in their environment which become polluted.
In a way, pollution has been ‘exported’
to developing countries. UN Conference on
Gandhi had said, “Modern man must re-establish
an unbroken link with nature and with life. He
must again learn to invoke the energy for growing
things and to recognize, as did the ancients
in India centuries ago, that one can take from
the earth and the atmosphere only so much as
one put back in the them” (Sharma1998).
Pollution 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.
What are pollutants? Any substance that
caused pollution is called a pollutant. A
pollutant may thus include any chemical or
agrochemical substance, biotic component or
its products or physical factor (heat) that is
released by man into the environment, that may
have adverse harmful or unpleasant effects. A
pollutant has also been defined as any solid,
liquid, or gaseous substance present in such
concentration as may be or tend to be injurious
to the environment”. Pollutants are the
residues of things we make, use and throw
away. There are many sources of such
pollutants. The lake and rivers are polluted by
wastes from chemical and other factories,

waste from human and the air by gases of
automobile exhausts, industries, thermal power
plants, etc.
Air Pollution
The atmosphere is an insulating blanket
around the earth. It is source of essential gases,
maintains a narrow difference of day and night
temperatures and provides a medium for long
distance radio communication. It also acts as
shield around the earth against lethal UV
radiations. With out atmosphere, there will be
no lightening, no wind, no clouds, no rains, no
snow and no fire.
Sources and Pollutants
Air pollution results mainly from
gaseous emissions of industry thermal power
stations, automobiles, domestic combustions,
smoke from the fire etc. From the different
sources of air pollution, a variety of pollutants
are released in to atmosphere. The main air
pollutants emitted from these different sources
and how these pollutants affect the human and
other living organisms on the planet are
described:
1. Carbon compounds: These are CO 2 and
Co, the former is released by complete
combustion of fossil fuels, and the latter
by automobile exhausts.
2. Sulfur compounds: These include SO 2 ,
HS and H 2 SO 4 mostly released by fossilfuel-based
power generating plants,
thermal plants, and refineries.
3. Nitrogen oxides: These include NO, NO 2 ,
HNO 3 mostly released by automobiles,
power plants and industries.
4. Ozone: Its level may rise in astrosphere
due to human activities.
5. Fluorides: These come from industries,
insecticides spray etc.
6. Hydrocarbons: These are chiefly benzene,
benz pyrene etc which are released by
automobiles and industries.
7. Metals: These include lead, nickel arsenic,
beryllium, tin, vanadium, titanium,
cadmium, etc. present in the air as solid
particles or liquid droplets or gases. They
are produced mostly by metallurgical
processes, automobiles, sea spray, etc.
8. Photochemical products: These are
photochemical smog, PAN, PB 2 N, etc.
released by automobiles.
9. Particulate matter: These are fly ash,
dust, grit and other suspended particulate
matter released from power plants and
industries (stone crushers)
10. Biological particulate matters: Bacterial
cells, fungal spores and pollens in air.
11. Toxicants other than heavy metals: These
are complex chemical substances released
during manufacture of other goods.
Carbon Compounds
The two important pollutants are CO 2 and CO.
Carbon Dioxide (CO 2 ): Major amount of
CO 2 is released in the atmosphere from burning
of fossil fuel (coal, oil, etc.) for domestic
cooking, heating, etc. and the fuel consumed in
furnaces of power plants, industries, hot mix
plants, etc. Another reason is the destruction of
the forest in the tropical regions of the world.
These ecosystems are efficient in removing
CO 2 and storing the C atoms in the structure of
the plant. From fossil fuels alone more than 18
x 10 2 ton of CO 2 are being released into
atmosphere each year. This gas is also emitted
during volcanic eruptions. An increase in CO 2
concentration in atmosphere may result into
disastrous effects as green house effect.
Greenhouse Effect and Global Warming:
Since CO 2 is confined exclusively to the
troposphere, its higher concentration may act a
serious pollutant. Under normal conditions the
temperature at the surface of the earth is
maintained by the energy balance of the sun
rays that strike the planet and heat that is
reradiated back in to space. However, when
there is an increase in CO 2 concentration, the
thick layer of this gas prevents the heat from
being reradiated out. This thick CO 2 layer thus
functions like the glass panels of a greenhouse
(or the glass windows of a motorcar), allowing
the sunlight to filter through but preventing the
heat from being radiated in outer space. This is
the so-called Greenhouse Effect.
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Thus, most heat is absorbed by CO 2 layer
and water vapor in the atmosphere, which adds
to the heat that is already present. The net
result is the heating up of the earth’s
atmosphere. Thus increasing CO 2 levels tends
to warm the air in the lower layers of
atmosphere on a global scale. Nearly 100 years
age the CO 2 level was 275 ppm. Today it is
350 ppm and by the year 2035 and 2040 it is
expected to reach 450 ppm. CO 2 increases the
earth temperature by 50% while CFCs are
responsible for another 20% increase. There
are enough (CFCs up there to last 120 years)
(Sharma 1999).
The excess CO 2 to some extent is
absorbed by the oceans. But with the
industrialization of the west and increased
consumption of energy, CO 2 was released in to
the atmosphere at a faster rate than the capacity
of oceans to absorb it. Thus its concentration
increased. There are other gases also which
contributed to green house effect. These are
SO 2 , NOx, CFCs discharged by industry and
agriculture. CFCs were widely used as
refrigerant gases in refrigeration’s and air
conditioners. There is a strong correlation
between the increase in temperature and the
amount of green house gases.
According to one projection, changes
will be the least in the tropics, and the most at
the poles. So Greenland, Iceland, Norway,
Sweden, Finland, Siberia and Alaska will be
among the most affected. The polar icecaps
would melt. The floating Western Antarctica
ice sheet could begin to melt. A rise of five
degrees would raise the sea level by five meters
within a few decades, threatening all the
densely populated coastal cities from Shanghai
to San Francisco.
According to an estimate, if all the ice on
earth should melt 200 feet of water would be
added to surface of all oceans, and low lying
coastal cities as Bangkok and Venice Would be
inundated. Due to green house effect, there
may occur more hurricanes and Ceylonese and
early snow melts in mountains causing more
floods during monsoon.
During the 1980s, scientists, governments,
and the public became concerned about the
possibility that the world may be getting
warmer. UNEP, for exmple, established the
Inter-governmental Panel on Climate Change
(IPCC) to study the issue and make
recommendations. Its first assessment was
published in 1990. In 1996, the IPCC
published its second assessment and concluded
that climate change is occurring and that it is
highly probable that human activity is an
important cause of the change. The UNEP had
appropriately chosen the slogan “Global
Warming” to alter the people on World
Environment Day - June 5, 1989. The
problem is that most vulnerable areas in the
developing world do not have economic
resources. The hardest hit may be developing
world, which discharge two fifths the of the
global carbon emissions each year. The effect
of global warming will be worsening human
health, rising sea level, disruptive of water
cycle, changing forest and natural areas and
challenges to agriculture and food supply
(Smith 2000).
Carbon Monoxide (CO): The chief source
are automobiles, though other involving a
combustion process as stoves, furnaces, open
fires, forest and bush fires, burning coal mines,
factories, power plants etc also give off co.
The principal source of this pollutant is the
exhaust product from motor vehicles in
common busy routes. Natural sources of this
gas are various plants and animals. Higher
animals produce some CO from hemoglobin
break down. Some CO is also liberated from
bile Juice. Break down of photosynthetic
pigments in algae also release some CO. The
smoke of automobiles and thermal power and
hot mix plants, stone crushers etc also
contribute to CO. level in air.
In the USA in 1965, 66 million tons of
CO. was emitted by automobile exhaust,
roughly 91% of this gas from all sources. In
Los Angels in 1971, the CO. emission from
automobiles was 8,960 tons daily and
comprised 98% of CO. from all sources. In the
air, its concentration is from traces to 0.5 ppm
(Sharma1999)
CO is harmful to those persons exposed
to congested high ways. Thus drivers are the
most affected people. CO causes difficulty in
breathing, causes headache, and irritation -1 of
mucous membranes. It combines with
hemoglobin of blood, reducing its O 2 –
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carrying capacity. (cigarette smokers have
increased hematocrit (per cent volume of red
blood cells), Within minutes of smoking. In
developed countries cigarettes are linked to at
least 80% of all death from lung cancer.
Sulfur Dioxide
The major source of SO 2 emission is
burning of fossil fuels in thermal Power plants,
smelting industries, and other process as
manufacture of sulfuric acid and fertilizers.
These account for about 75% of the total SO 2
emission. The rest 25% emission is from
automobiles and petroleum refineries. In
U.S.A in 1970 there was emitted 37 million
tons of SO 2 , which is likely to go up to 95
million tons by 1990. It is believed that about
10 9 million tons SO 2 are added each year in to
the global environment.
SO 2 causes intense irritation to eyes and
respiratory tract. It is absorbed in the moist
passage of upper respiratory tract, leading to
swelling and stimulated mucus secretion.
This gas causes damage to higher plants,
forming necrotic areas on leaf. In most plants
leaf are collapses under intense exposure to
SO 2 . SO 2 is also involved in the erosion of
building materials as limestone Marble, the
slate use in roofing, mortar and deterioration of
statues. Petroleum refineries, Smelters, Kraft
paper mills deteriorate the adjoining historic
movements.
Hydrogen Sulphide
The chief source of H 2 S is decaying
vegetation and animal matter, especially in
aquatic habitats. Sulfur springs, volcanic
eruptions, coal pits and sewers also give of this
gas. About 30 million tons of H 2 S every year
is released by oceans and 60 to 80 million tons
per year by land. Industries emit 3 million ton
5 every year. The chief industrial sources of
H 2 S are, users of sulfur containing fuels.
At low concentration H 2 S causes
headaches, nausea, collapse, coma and final
death. Un pleasant odor may destroy the appetite
at 5 ppm level in some people. A concentration
of 150 ppm may cause conjunctivitis and
irritation of mucus membranes. This gas
readily passes through alveolar membrane of
the lung and penetrates the blood stream. Death
occurs due to respiratory failures.
Nitrogen Oxides (NO x )
Even in unpolluted atmosphere, there are
present measurable amounts of nitrous oxide,
nitric oxide and nitrogen dioxide. Of these,
nitric oxide (NO) is the pivot compound. It is
produced by combustion of O 2 and N 2 during
lightning discharges and by bacterial oxidation
of NH 3 to form poisonous NO 2 . NO 2 may react
with water vapor in air to form HNO 3 . This
acid combines with NH 3 to form ammonium
nitrate. About 95% of the NO x is emitted as
NO and remaining 5% as NO 2 . In metropolitan
cities, vehicular exhaust is the most important
source of nitrogen oxides.
Nitrous Oxide (N 2 O): This gas has so far
not been implicated in air pollution.
Nitric Oxide (NO): The chief source of this
gas is the industries manufacturing HNO 3 and
other chemicals, and the automobile exhausts.
Nitric oxide, is responsible for several
photochemical reactions in the atmosphere, in
the formation of pollutants like PAN, O 3 ,
carbonyl compounds etc. in the presence of
other organic substances. There is little
evidence o the direct role of this gas is causing
a health hazard, at the levels found in urban air.
Nitrogen Dioxide (NO 2 ): A deep reddish
brown gas, which is the only widely prevalent
colored pollutant gas. This gas is the chief
constituent of photo chemical smog. NO 2
causes irritation of alveoli, leading to
symptoms resembling emphysema. Lung
inflammation may be followed by edema and
final death.
Acid Rains
Oxides of sulfur and nitrogen are
important gaseous pollutants of air. These
oxides can travel thousands of Kilometers in
the atmosphere. They stay in the atmosphere
and are to be oxidized in to acids. Sulfuric and
Nitric acids are the main acids, which dissolve
in the water in the atmosphere and fall to the
32

ground as acid rain or may remain in the
atmosphere in clouds and fogs.
The acid rain problem has increased due
to industrialization. Burning of fossil fuels for
power generation contributes to almost 60 –
70% of total SO 2 emitted globally. Emission
of NO x from human activity ranges between 20
- 90 million tons annually over the globe.
Acid rains are a great threat to British
environment as to central Europe and Southern
Scandinavia. In 1974 acid rains over Scotland
were found to be sourer than vinegar (pH 2.4).
Much of the falling snow in Britain is now
highly acidic.(Smith 2000) If it does not melt
it may turn in to a pollution time bomb. Heavy
winds pick up acid rain from factories in
Britain and Frances to Sweden. Ninety percent
of acid rains of Norway and 75% of Sweden
are due to drifted acid rain oxides. It is a major
political issue.
Acid rains create complex problems and
their impacts are far reaching. They increase
soil acidity, this affecting land flora and fauna;
cause acidification of lakes and streams thus
affecting aquatic life, affects crop productivity
and human health. Besides these they also
corrode buildings, monuments, bridges, fences,
railing, etc.
Ozone (O 3 )
Ozone layer in the stratosphere protects
us from the harmful UV radiation from Sun.
The depletion of this O 3 layer by human
activities may have serious implications and
this has become a subject of much concern
over the last few years. Ozone is also formed
in the atmosphere through chemical reactions.
The atmospheric ozone is now being regarded
as potential danger to human health and crop
growth.
The ozone layer has two important and
interrelated effects. It absorbs UV light and
thus protects all life on earth from harmful
effects of radiation. By absorbing the UV
radiation the ozone layer heats the stratosphere,
causing temperature inversion. It limits the
vertical mixing of pollutants, there by causing
the dispersal of pollutants over large areas and
near the earth’s surface. That is why a thick
cloud of pollutants hangs over the atmosphere
33
in industrialized areas causing several un
pleasant effects. The stratosphere could be
regarded as a sink, but unfortunately, these
pollutants (CFC s ) react with the ozone and
deplete it.
The ozone near the earth’s surface in the
troposphere creates pollution problems. Ozone
and peroxy acetyl nitrate (PAN) and hydrogen
peroxide are formed by the reaction between
NO 2 and hydro carbon in sunlight. These
pollutants cause photo chemical smog. Higher
levels of O 3 in the atmosphere protect us, and is
harmful when it comes in direct contact with us
and plants at earth’s surface.
Any depletion of ozone, have catastrophic
effects on life systems of the earth. Major
pollutants responsible for this depletion are
chlorofluoro carbons, nitrogen oxides and
hydrocarbons. CFC s are used as coolants in air
conditioners and refrigerators, cleaning
solvents, aerosol propellants and in foam
insulation. They escape as aerosol in the
stratosphere. The threat to O 3 is mainly from
CFCs. Depletion of O 3 cause temperature
changes on the earth.
Cancer is the best established threat to
man, especially relating to skin like melanoma.
The other disorders are cataracts, destruction of
aquatic life and vegetation and loss of
immunity. Nearly 6,000 people die of such
cancers in USA each year.
There are also indirect effects. If the
plants exposed the UV radiation showed
reduction in chlorophyll content, reduction in
growth and increase in harmful mutations.
Global efforts: The first global conference
on the depletion of ozone layer was held in
Vienna (Austria) in 1985, the year, scientists
discovered hole in south pole. British team
discovered a hole in ozone layer as large as that
of the United States. This was followed by
Montreal Protocol in 1987 which called for a
50% cut in the use of CFC s by 1998 reducing
to the level of 1986, 95% of CFCs is released
by European countries, USA, USSR, and
Japan. The three-day international “Saving the
ozone layer” conference was organized jointly
in London in March 1989 by the British
government and the UNEP.
There was another international
conference on ozone at Helsinki in may 1989

to revise the Montreal Protocol. As many as 80
nations agreed to have a total ban on chemicals
that cause ozone depletion by 2,000 A.D. The
agreement for CFC elimination by 2,000 AD is
needed as a major step towards environmental
protection(.P.D.Sharma1999)
Fluorides
Fluorides in atmosphere come from
industrial process of phosphate fertilizers,
ceramics, aluminum, fluorinated hydrocarbons,
uranium and other metals. The pollutant is in
gaseous or particulate state. In air fluoride
chiefly comes from smoke of industries,
volcanic eruptions, and insecticide sprays. In
plants it causes tip burn. Fluoride pollution in
man and animals is mainly through water. In
minute amounts, fluorides are beneficial
helping prevention of tooth-decay in man.
However, higher levels become toxic.
Hydrocarbons
Among the hydrocarbons the chief air
pollutants are benzene, benzepyrene, and
methane. The Motor vehicles are their chief
source. These are emitted by evaporation of
gasoline through carburetors, crankcase etc.
They have carcinogenic effects on lung.
They combine with NOx under UV component
of light to form other pollutants like PAN and
O 3 which cause irritation of eye, nose, throat
and respiratory distress.
Benzene
It is a liquid pollutant emitted from
gasoline. It causes lung cancer. Benzepyrene is
most potent cancer inducing hydrocarbon
pollutant. It is also present in small amounts in
smoke, tobacco, charcoal boiled stakes and
gasoline exhaust.
Methane
concentration may cause explosions. At high
levels in absence of oxygen, methane may be
narcotic on man.
Metals
In air, the common metals present are
mercury, lead, zinc and cadmium. They are
released from industries and human activities
in the atmosphere.
Mercury: Mercury is a liquid volatile metal
(found in rock and soil) is present in air, as a
result of human activities. Human use mercury
compounds in production of fungicides, paints,
cosmetics, paper pulp etc. By inhalation
nervous system, liver, eyes are damaged.
Infant may be deformed. Other symptoms are
headache, fatigue, anxiety, loss of appetite etc.
Lead: Lead is added to gasoline to reduce
Knocking are emitted in to the air with the
exhaust as volatile lead halides (bromides &
chloride) About 75% of lead burnt in gasoline
comes out as lead halides through tail pipe in
exhaust gases. Of this 40% settles an the
ground 60% gels in to air. Lead inhalation
causes reduced hemoglobin formation, thus
leading to anemia. It also damage RBCs
resulting in infections of liver & kidney in
man.
Zinc: Zinc in air occurs mostly as white zinc
oxide fumes & is toxic to man.
Cadmium: It occurs in air due to industries.
Industries engage in extraction, refining,
electroplating and welding of cadmium
containing materials and refining of copper,
lead and zinc are the major source of cadmium
in air. This metal is emitted as vapor, it
quickly reacts to form oxide, sulfate, or
chloride compounds. It is poisonous and
accumulates in human liver and kidney. It
causes hypertension, emphysema and kidney
damage.
Photochemical Products
Methane is a gaseous pollutant, in
minute quantity in air. In nature it is produced
during decay of garbage, aquatic vegetation
etc. This is also released due to burning of
natural gas and from factories. Higher
34
NOx, hydrocarbons and O 3 in the
atmosphere are air pollutants. These may react
with each other the presence of sunlight,
producing secondary pollutants in the air. The
main photochemical products are olefins,

aldehydes, ozone, PAN, PB 2 N and
photochemical smog.
Olefines: Olefines are produced directly
from exhaust and in the atmosphere from
ethylene. They affect plants, especially they
wither sepals of orchid flowers, retard the
opening of carnation flowers & also high level
retard the growth of tomatoes.
Among the photochemical products,
benzepyrene, PAN, and peroxy benzoil nitrate
(PB 2 N) are the most potent pollutants.
Benzepyrene is carcinogenic. PAN is an eye
irritant. PAN and O 3 cause respiratory distress.
Photochemical Smog: It is produced as
a result of photochemical reaction among NO x ,
hydrocarbons and oxygen. Photochemical
smog formation occurred only during night or
cloudy days. Smog is formed by the
combination of smoke and Fog which
characterized air pollution episode in
London, Glasgow, Manchester and other
cities of U.K where sulfur rich coal was used.
The U.K smog was a mixture of reducing
pollutants and has been called reducing smog,
where as Los Angeles smog a mixture of
oxidizing pollutants is called oxidizing smog
which is produced as a result of pollution by
domestic fires and exhaust from motor
vehicles.
Photochemical smog adversely affects
plants, human health and Materials. The
oxidants enter as part of inhaled air, interfere
with respiratory process causing asthma and
bronchitis in epidemic form. Another serious
disease is emphysema.
The smoke, fog, mist, dust, soot etc in
the smog reduce the visibility, damage crop,
and cause corrosion of metals, stones, building
materials, painted surfaces, paper, leather etc.
Particulate Matter: This is a discrete mass
of any material, except pure water, that exist as
solid or liquid in atmosphere and of
microscopic or submicroscopic dimensions. It
arises in atmosphere from natural as well as
man made sources. Natural sources are soil
and rock debris (dust) volcanic emission, forest
fires and reaction between natural gas
emissions.
Human activities are industrial
operations (mining, smelting, polishing,
35
textiles, pesticides, fertilizers and chemical
production), industrial fugitive process
(loading and transfer operations) non industrial
fugitive process (road way dust, agricultural
operations, construction, fire etc.) vehicles
exhaust, clutch and break wear.
Particulate matter is injurious to health.
Soot, lead particles, asbestos, flash, volcanic
emission, pesticides, H 2 SO 4 mist, metallic dust,
cotton and cement dust, etc. when inhaled by
man cause respiratory diseases such as
tuberculosis and cancer.
In addition there are many kinds of
biological particulate matter that suspended in
atmosphere. These are bacterial cells, spores,
pollen grains, and fungal spores. These cause
allergy, bronchial disorders and any other
diseases in man animals & plants.
Hazardous and Toxic Substances
Hazardous substances are those that can
cause harm to humans or the environment. The
U.S. Environmental protection Agency (EPA)
defines hazardous materials have one or more
of the following characteristics.
1. Ignitability – substances that catch fire
readily (e.g. gasoline and alcohol).
2. Corrosivity – substances that corrode
storage tanks and equipment (e.g. acid).
3. Reactivity – substances that are
chemically unstable and may explode or
create toxic fumes when mixed with
water. (eg. conc. H 2 SO 4 ).
4. Toxicity – substances that are injurious to
health when in hailed e.g. chlorine,
ammonia, pesticides and formaldehyde.
Toxic substances are poisonous and cause
death or serious injury to humans and other
organisms. They are: (i) heavy metals, and
(ii) non-biodegradable synthetic organics.
Heavy Metals
The most dangerous heavy metals are
lead, mercury, arsenic, cadmium, tin,
chromium, zinc and copper. These metals are
widely used in industry particularly in metal
working or metal plating shops, and in such
products as batteries and electronics. They are
also used in pesticides and medicines, used in

paints pigments glazes, inks and dyes. Thus
heavy metals may enter the environment
wherever any of these products are produced,
used and ultimately discarded.
Heavy metals are toxic because, as ions
or in certain compounds, they are soluble in
water and may be readily absorbed in to the
body, where they combine with and inhibit the
functioning of particular vital enzymes. Even
very small amounts can have physiological or
neurological consequences.
The mental retardation caused by lead
poisoning and crippling birth defects caused by
mercury are well known examples.
Non-biodegradable Synthetic Organic
Compounds
Synthetic organic compounds are
plastics, synthetic fibers, synthetic rubber,
modern paint like coatings, solvents, pesticides,
wood preservatives and hundreds of other
products.
These products are toxic because they
are absorbed in to the body, there they interact
with the particular enzymes, but their non
biodegradability prevents them from being
broken down or processed further. The result
is that they upset the system. When a person
ingests a high dose, the effect may be an acute
poisoning and death.
With a low dose over extended periods,
the effects are insidious and can be mutagenic,
carcinogenic, or teratogenic (birth defect).
They may cause liver and kidney dysfunction,
sterility and numerous other physiological and
neurological problems.
The troublesome class of synthetic
organics is the halogenated hydrocarbons. It is
organic compounds in which one or more of
the hydrogen atoms have been replaced by
atoms of chlorine, bromine, fluorine, or iodine.
These four elements are classed as halogens.
Of the halogenated hydrocarbons, the
chlorinated hydrocarbons are the most
common. Organic chlorides are used in
plastics, pesticides, solvents electrical
insulation, flame retardants and many other
products.
Bio-accumulation and Bio-magnification
Heavy metals and non-biodegradable
synthetic organic compounds are accumulated
in the organisms. Because of accumulation in
small amounts received over a long period of
time may reach to toxic levels. This
phenomenon is referred to as bio-accumulation
(Nebel 1998).
Organisms act as filter for heavy metals
and synthetic organics. Heavy metals are
removed from solution. Synthetic organics are
highly soluble in lipids (fats and fatty
compounds) but sparingly soluble in water. As
they pass through cell membranes, which are
lipid, they come out of water solution and enter
in to the lipid of the body. Thus traces of
heavy metals and synthetic organics that are
absorbed by the water and water soluble wastes
are passed in the urine. Since the body has no
mechanism to excrete the heavy metals and
synthetic organics, trace levels consumed over
time gradually accumulate in the body and
produce toxic effects.
Each organism accumulates the
contamination in its food, so it accumulates in
its body. All the contaminants accumulated by
the higher organism through smaller organism
when they consume them as food. This
multiplying effect of bioaccumulation that
occurs through the food chain is called biomagnification.
The pesticide D.DT is an
example of bio-magnification (Nebel 1998).
There is no warning symptoms in the
beginning, until the contaminant concentration
in the body are high enough to cause problems.
Then it is too late to do much about.
There are also several polycentric
aromatic hydrocarbons. (PAHs), which arrive
in the atmosphere from coal production,
vehicle disposal, wood burning, municipal
incineration, petroleum refining and coal
furnaces. In general they do not produce
adverse effect in their parent forms. However
if metabolized by enzymes of the body, they
produce intermediates which are capable of
producing cancer.
36

Prevention and Control of Air Pollution.
We have seen that the main sources of air
pollution are motor vehicles, industries –
particularly their chimney wastes, and fossil
fuel (coal) based plants, as thermal power
plants. Steps are to be taken to control
pollution at source (prevention) as well as after
the release of pollutants in the atmosphere.
Vehicular Pollution
How can we control the air pollution by
motor vehicles?
1. By checking pollutant emission from
vehicular exhaust. This can be achieved by:
(i) using gas additives to improve
combustion.
(ii) more exact timing of fuel feeding.
(iii) using new proportion of gasoline and
air.
(iv) injecting air to exhaust to convert
exhaust compounds to less toxic
materials.
(v) updating of engine design to improve
combustion.
(vi) The three pollutant, CO, NO x and
hydrocarbon can eliminate by
updating engine design. Very recently,
L.K. Bharati of Bombay has claimed
to have devised a simple attachment
thermo reactor, to scrub air pollution
by motor vehicle. The reactor is fitted
to exhaust tailpipe and it converts
carbon monoxide in to pure oxygen.
2. By using electrostatic precipitators
(ESPs)
To remove the particles from gas stream,
the electrical forces are applied within the
chamber in the precipitator. Suspended
particles become charged or ionized and they
are attracted to charged electrodes and removed
99% particulate pollutant can remove by this
method. ESPs work very well in power plants,
paper mills, cement factory carbon block plants
etc.
Conclusion
The environment and its relation to
humanity is one of the most important
problems of the present time. Environmental
problems are man made. Hence man naturally
is the solution to most of them. With his
unique technological capabilities he can
increase or decrease human miseries.
Exploitation of nature was considered
inevitable for human survival. Hence man is
obliged to re examine his values, attitudes,
behavior, life styles and where necessary to
alter them to ensure his survival. To day we
have both knowledge and technology for a
sound ecological management. We know how
to control pollution, how to recycle materials
and nutrients and harness solar energy. What is
required is only a matter of desire and will as
individuals and societies to put what is known
in to practice. All powers are given to man to
preserve a quality environment. Our
environmental recession making should reflect
this fundamental purpose of human existence.
References
Enger, D.E.; and Smith, B.F. 2000.
Environmental Science. A Study of
Interrelationship, 8 th ed. McGraw-Hill,
New York, NY, USA.
Nebel, B.J.; and Wright, R.T. 1998.
Environmental Science, 6 th ed. Prentice
Hall, Upper Saddle River, NJ, USA.
Sharma, P.D. 1998. Ecology and Environment,
7 th ed. Rastogi Publ., Meerut, New Delhi,
India.
Sharma, P.D. 1999. Environmental Biology,
2 nd ed. Rastogi Publ., Meerut, New Delhi
India.
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