Q.16 What is air pollution? What are its
effects on human health? Discuss the measures used for controlling air
pollution. (AKTU. - 2004-05, 2008-09)
Ans. Air Pollution: - (AKTU. - 2010 - 11)
Air pollution is basically the presence of
foreign substances in air in excessive concentration which adversely affects
the well being of the individual or causes damage to property.
Air pollution problems are
generally associated with the arrival of the industrial revolution. Population
explosion has led to urban growth, extensive industrial development and
automobile revolution, all of which are to be blamed for threatening to make
the earth’s environment inhospitable for future generations.
Effects
of Air Pollution on Human Health: -
The various health effects are as under:
1. Eye irritation can be
caused by many air pollutants
2. Nose and throat
irritation can be caused by pesticides, etc.
3. Gaseous pollutants like
and hydrocarbons can cause odour nuisance even at low concentrations.
4. A variety of
particulates, particularly pollens, can initiate asthmatic attacks.
5. High concentrations of
SPM (Suspended particular matter) and photochemical smog can aggravate chronic
pulmonary diseases like bronchitis and asthma.
6. Carbon monoxide, which is
two hundred times more reactive than oxygen, combines with haemoglobin in the
blood and consequently increases stress on those suffering from cardiovascular
and pulmonary diseases. Similarly, nitric oxide (NO) can react with hemoglobin
and reduce the oxygen carrying capacity of the blood.
7. Hydrogen fluoride can cause fluorosis and
mottling of teeth.
8. Air pollutants such as
polycyclic organic compounds, aliphatic hydrocarbons, etc. can cause cancer.
9. Dust particles can cause
dust specific respiratory diseases, such as silicosis (associated with silica
dust), asbestosis (associated with asbestos dust), etc.
10. Heavy metals, like lead
(emitted from vehicles), may enter the body through the lungs and can cause
poisoning. Its high concentration can damage liver and kidney, and can cause
abnormality in fertility and pregnancy, and mental development of children get
affected.
11. Exposure to radioactive
isotopes like Iodine 131, Phosphorus 32, Cobalt 60, Radium 226, etc. can cause
anaemia (iron deficiency), leukaemia (RBC deficiency), cancer, and genetic
defects.
Approaches to Air Pollution Control: -
Basically,
there are four approaches available for the control of emissions discharged
into the atmosphere. They are:
(i) Dispersion of
source locations. Air
pollution can be controlled/checked by dispersion of the sources of air
pollutants, through allocation of land, i.e. by proper planning and zoning of
industrial areas.
(ii) Dilution. By using tall stacks for industries or
thermal plants, the emissions or pollutants can be discharged at a sufficient
height from ground, where the air movement, both horizontal and vertical, is
more and chances of downward movement of air (i.e., inversion conditions) are
less. This will help in dispersion of pollutants over a larger area in less
time, and hence dilute the concentrations of pollutants near the source.
(iii) Reduction
at source by process changes. This can be achieved by:
(a) Substitution of raw materials e.g., the
use of low-volatile coal in place of high-volatile coal, eliminates smoke and
soot.
(b) Substitution of
fuel; e.g. desulphurization and de-ashing reduce emissions of SO2, SPM (suspended particulate matter) and ash. Similarly, natural gas can be used in
place of coal, to minimize emissions.
(c) Modification of the
process; e.g., in case of disposal of combustible refuse, sanitary landfill can
be used instead of incinerators.
(d) Modification of the
process equipment, or repair and maintenance of existing equipment help in reducing atmospheric pollution.
(iv) Reduction at source
by using control equipment.
This is the most effective method for reducing air pollution at source. Various
control devices are used for controlling different types of pollutants emitted
from different sources.
Q.17 Explain sources and effects of air
pollution. (AKTU. - 2008-09, 10 - 11, 11 - 12)
Related
Questions -
Q. What are the sources of air
pollutants? (AKTU. - 2012 - 13)
Ans. Sources
of Air Pollution: -
The sources may be natural or anthropogenic
(man-made). Natural sources include volcanic eruptions, forest fires, cosmic
dust, pollen grains,
Sources of Air Pollutants
sand
storms, hydrogen sulphide and methane from anaerobic decomposition of organic
matter, etc. Man-made sources such as burning of fossil fuels, emissions from
vehicles, rapid industrialization, agricultural activities, warfares, etc. are
major causes of air pollution. The sources may also be classified as stationary
or mobile sources.
Effects of Air Pollution: -
(a) Effects of Air Pollution on Human Health: -
Go through
previous question.
(b) Effect of Air Pollution on Plants: -
(i) SO2 bleaches the leaf surface and causes chlorosis
(i.e. loss of chlorophyll and yellowing of the leaf) especially in leafy
vegetables.
(ii) NO2 causes premature leaf fall (abscission) and
suppressed growth of plants resulting in reduced yields of crop plants.
(iii) Ozone causes
necrosis (dead areas on a leaf structure) and damages leaves.
(iv) PAN
(peroxyacylnitrate) damages leafy vegetables causing premature fall,
discolouration and curling of sepals.
(c) Effect of Air Pollution on Animals: -
In case of animals, it is two-step process
:
(i) Accumulation of
air pollutants in the vegetation and forage; and
(ii) Subsequent
poisoning of the animals, when they eat the contaminated vegetation/forage.
