Human population size has grown enormously over the

last hundred years. This means increase in demand for

food, water, home, electricity, roads, automobiles and

numerous other commodities. These demands are exerting

tremendous pressure on our natural resources, and are

also contributing to pollution of air, water and soil. The

need of the hour is to check the degradation and depletion

of our precious natural resources and pollution without

halting the process of development.

Pollution is any undesirable change in physical,

chemical or biological characteristics of air, land, water or

soil. Agents that bring about such an undesirable change

are called as pollutants. In order to control environmental

pollution, the Government of India has passed the

Environment (Protection) Act, 1986 to protect

and improve the quality of our environment (air, water

and soil).

16.1 AIR POLLUTION AND ITS CONTROL

We are dependent on air for our respiratory needs. Air

pollutants cause injury to all living organisms. They

reduce growth and yield of crops and cause premature

death of plants. Air pollutants also deleteriously affect the

respiratory system of humans and of animals. Harmful

CHAPTER 16

ENVIRONMENTAL ISSUES

16.1 Air Pollution and Its

Control

16.2 Water Pollution and Its

Control

16.3 Solid Wastes

16.4 Agro-chemicals and

their Effects

16.5 Radioactive Wastes

16.6 Greenhouse Effect and

Global Warming

16.7 Ozone Depletion in the

Stratosphere

16.8 Degradation by Improper

Resource Utilisation and

Maintenance

16.9 Deforestation

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effects depend on the concentration of pollutants, duration of exposure

and the organism.

Smokestacks of thermal power plants, smelters and other industries

release particulate and gaseous air pollutants together with harmless

gases, such as nitrogen, oxygen, etc. These pollutants must be separated/

filtered out before releasing the harmless gases into the atmosphere.

Figure 16.1 Electrostatic precipitator

There are several ways of removing particulate matter; the most widely

used of which is the electrostatic precipitator (Figure 16.1), which can

remove over 99 per cent particulate matter present in the exhaust from a

thermal power plant. It has electrode wires that are maintained at several

thousand volts, which produce a corona that releases electrons. These

electrons attach to dust particles giving them a net negative charge. The

collecting plates are grounded and attract the charged dust particles.

The velocity of air between the plates must be low enough to allow the

dust to fall. A scrubber (Figure 16.1) can remove gases like sulphur

dioxide. In a scrubber, the exhaust is passed through a spray of water or

lime. Recently we have realised the dangers of particulate matter that are

very very small and are not removed by these precipitators. According to

Central Pollution Control Board (CPCB), particulate size 2.5 micrometers

or less in diameter (PM 2.5) are responsible for causing the greatest harm

to human health. These fine particulates can be inhaled deep into the

lungs and can cause breathing and respiratory symptoms, irritation,

inflammations and damage to the lungs and premature deaths.

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Automobiles are a major cause for atmospheric pollution atleast in

the metro cities. As the number of vehicles increase on the streets, this

problem is now shifting to the other cities too. Proper maintenance of

automobiles along with use of lead-free petrol or diesel can reduce the

pollutants they emit. Catalytic converters, having expensive metals namely

platinum-palladium and rhodium as the catalysts, are fitted into

automobiles for reducing emission of poisonous gases. As the exhaust

passes through the catalytic converter, unburnt hydrocarbons are

converted into carbon dioxide and water, and carbon monoxide and nitric

oxide are changed to carbon dioxide and nitrogen gas, respectively. Motor

vehicles equipped with catalytic converter should use unleaded petrol

because lead in the petrol inactivates the catalyst.

In India, the Air (Prevention and Control of Pollution) Act came

into force in 1981, but was amended in 1987 to include noise as an air

pollutant. Noise is undesired high level of sound. We have got used to

associating loud sounds with pleasure and entertainment not realising

that noise causes psychological and physiological disorders in humans.

The bigger the city, the bigger the function, the greater the noise!! A

brief exposure to extremely high sound level, 150 dB or more generated

by take off of a jet plane or rocket, may damage ear drums thus

permanently impairing hearing ability. Even chronic exposure to a

relatively lower noise level of cities may permanently damage hearing

abilities of humans. Noise also causes sleeplessness, increased heart

beat, altered breathing pattern, thus considerably stressing humans.

Considering the many dangerous effects of noise pollution can you

identify the unnecessary sources of noise pollution around you which

can be reduced immediately without any financial loss to anybody?

Reduction of noise in our industries can be affected by use of sound-

absorbent materials or by muffling noise. Stringent following of laws laid

down in relation to noise like delimitation of horn-free zones around

hospitals and schools, permissible sound-levels of crackers and of loud-

speakers, timings after which loudspeakers cannot be played, etc., need

to be enforced to protect ourselves from noise pollution.

16.1.1 Controlling Vehicular Air Pollution: A Case

Study of Delhi

With its very large population of vehicular traffic, Delhi leads the coun-

try in its levels of air-pollution – it has more cars than the states of

Gujarat and West Bengal put together. In the 1990s, Delhi ranked

fourth among the 41 most polluted cities of the world. Air pollution

problems in Delhi became so serious that a public interest litigation

(PIL) was filed in the Supreme Court of India. After being censured very

strongly by the Supreme Court, under its directives, the government

was asked to take, within a specified time period, appropriate meas-

ures, including switching over the entire fleet of public transport, i.e.,

buses, from diesel to compressed natural gas (CNG). All the buses of

Delhi were converted to run on CNG by the end of 2002. You may ask

the question as to why CNG is better than diesel. The answer is that

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CNG burns most efficiently, unlike petrol or diesel, in the automobiles

and very little of it is left unburnt. Moreover, CNG is cheaper than petrol

or diesel, cannot be siphoned off by thieves and adulterated like petrol

or diesel. The main problem with switching over to CNG is the difficulty

of laying down pipelines to deliver CNG through distribution points/

pumps and ensuring uninterrupted supply. Simultaneously parallel

steps taken in Delhi for reducing vehicular pollution include phasing

out of old vehicles, use of unleaded petrol, use of low-sulphur petrol

and diesel, use of catalytic converters in vehicles, application of stringent

pollution-level norms for vehicles, etc.

The Government of India through a new auto fuel policy has laid

out a roadmap to cut down vehicular pollution in Indian cities. More

stringent norms for fuels means steadily reducing the sulphur and

aromatic content in petrol and diesel fuels. Euro III norms, for example,

stipulate that sulphur be controlled at 350 parts-per-million (ppm) in

diesel and 150 ppm in petrol. Aromatic hydrocarbons are to be contained

at 42 per cent of the concerned fuel. The goal, according to the roadmap,

is to reduce sulphur to 50 ppm in petrol and diesel and bring down the

level to 35 per cent. Corresponding to the fuel, vehicle engines will also

need to be upgraded.

Mass Emission Standards (Bharat Stage II which is equivalent to

Euro-II norms) are no more applicable in any of the cities of India.

Details of the latest Mass Emission Standards in India are provided

below (Table 16.1)

Type of Vehicles Norms Cities of Implementation

4 Wheelers Bharat Stage IV Throughout the country

since April 2017

3 Wheelers Bharat Stage IV Throughout the country

since 1st April 2017

2 Wheelers Bharat Stage IV Throughout the country

since April 2017

Table 16.1: Table Showing the Mass Emission Standards in India

Thanks to the efforts made, the air quality of Delhi has significantly

improved. According to an estimate, a substantial fall in CO

and SO

level has been found in Delhi between 1997 and 2005.

16.2 WATER POLLUTION AND ITS CONTROL

Human beings have been abusing the water-bodies around the world by

disposing into them all kinds of waste. We tend to believe that water can

wash away everything not taking cognizance of the fact that the water

bodies are our lifeline as well as that of all other living organisms. Can

you list what all we tend to try and wash away through our rivers and

drains? Due to such activities of human kind, the ponds, lakes, stream,

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