CHAPTER FOUR

ATMOSPHERE

14.1 ATMOSPHERIC POLLUTION – MAIN SOURCES

The atmosphere consists of a mixture of gases that completely surround the earth. It extends to an altitude of 800 to 1000 kms above the earth’s surface, but is deeper at the equator and shallow at the poles. About 99.9% of the mass occurs below 50 Km and 0.0997% between 50 and 100 km altitude. Major polluting gases/ particles are confined to the lowermost layer of atmosphere known as Troposphere. That extends between 8 and 16 Kms above the earth surface.

The main sources of atmospheric pollution may be summarized as follows:

a) The combustion of fuels to produce energy for heating and power generation both in the domestic sector as well as in the industrial sector.

b) The exhaust emissions from the transport vehicles that use petrol, or diesel oil etc.

c) Waste gases, dust and heat from many industrial sites including chemical manufacturers, electrical power generating stations etc.

ENVIRONMENT POLLLUTION DUE TO ENERGY USE

A considerable amount of air pollution results from burning of fossil fuels. Fuels are primarily derived from fossilized plant material and consist mainly of carbon and/or its compounds. The household sector is the largest consumer of energy in India, accounting for 40-50% of the total energy consumption. As per a report of Planning Commission the share of the household sector in the final use of energy declined although retaining its dominant share at 58.9% in 1987. The most abundantly

used fossil fuel for cooking is the wood, which is almost 61% of the total fuel demand for cooking. Burning of traditional fuels introduces large quantities of CO₂ when the combustion is complete, but if there is incomplete combustion and oxidation then Carbon monoxide (CO) is produced, in addition to hydrocarbons. Incomplete combustion of coal produces smoke consisting of particles of soot or carbon, tarry droplets of unburnt hydrocarbons and CO. Fossil fuels also contain .5 – 4.0% of sulphur which is oxidized to SO₂ during combustion.

The environmental effects of various fuels namely coal , oil, nuclear, etc. are of growing concern owing to increasing consumption levels. The combustion of these fuels in industries and vehicles has been a major source of pollution. Coal production through opencast mining; its supply to and consumption in power stations; and industrial boilers leads to particulate and gaseous pollution which can cause pneumoconiosis, bronchitis, and respiratory diseases. Another major impact of coal mining is land degradation, especially of forest areas.

The consumption of petroleum products in vehicles, industries and domestic cooking activities results in the emission of pollutants in large quantities. Radioactive emissions from nuclear power plants are of grave concern as they can cause serious impact both in terms of spatial and inter-generational concerns. In addition, two key problems are long term waste disposal and the eventual decommissioning of plants. Due to limited reserves of petroleum , main emphasis needs to be given to non conventional energy sources such as wind energy, solar energy and ocean energy.

INDUSTRIAL EMISSIONS

Air borne emissions emitted from various industries are a cause of major concern. These emissions are of two forms, viz. solid particles (SPM) and gaseous emissions (SO₂, NO_x, CO, etc.). Liquid effluents, generated from certain industries, containing organic and toxic pollutants are also a cause of concern. Heavily polluting industries were identified which are included under the 17 categories of highly polluting industries for the purpose of monitoring and regulating pollution from them. The Ministry of Environment and Forests has, over the last two decades, developed standards for regulating emissions from various industries and emission standards for all the polluting industries including thermal power stations, iron and steel plants, cement plants, fertilizer plants, oil refineries, pulp and paper , petrochemicals, sugar, distilleries and tanneries have been prescribed . The industrial units in India are largely located in the States of Gujarat, Maharastra, Uttar Pradesh, Bihar, West Bengal and Madhya Pradesh. The highest concentration of sulpher dioxide and oxides of nitrogen is therefore often found in cities located in these states. Some other industrial estates in Delhi, Punjab, Rajasthan and Andhra Pradesh are also becoming critical.

ROAD TRANSPORT:

Road vehicles are the second major source of pollution. They emit CO, HCs, NO_X, SO₂, and other toxic substances such as TSP and lead. Diesel engines are much less polluting than petrol engines. Both types of engines are not very efficient converters of fuel energy. However, diesel types, with a conversion efficiency of around 30%, must be more efficient and use less fuel than petrol types with a 15-20% conversion efficiency. Both types of engines have incomplete combustion of fuel so the major pollutant is CO, amounting to 91% by weight of all vehicle emissions.

The primary pollutants produced in vehicle emissions undergo a series of complex interrelated chemical reactions in the troposphere and lower stratosphere to form secondary products.

Four factors make pollution from the vehicles more serious in developing countries.

i) Poor quality of vehicles creating more particulates and burning fuels inefficiently.

ii) Lower quality of fuel being used leads to far greater quantities of pollutants.

iii) Concentration of motor vehicles in a few large cities

iv) Exposure of a larger percentage of population, that lives and moves in the open.

HARMFUL EFFECTS OF EMISSIONS:

The high concentration of particulates in the atmosphere over large urban and industrial areas can produce a number of general effects. Smoke and fumes can increase the atmospheric turbidity and reduce the amount of solar radiation reaching the ground. The overall effect of air pollution upon the biosphere and the built environment can be broadly considered under 3 headings: The effect upon
i) buildings and materials

ii) soil, vegetation, crops and animal life

iii) human beings

i) Buildings and Materials: The fabric of buildings, that are surrounded by heavily polluted air for years undergo chemical changes. Gradual erosion takes place and this is only too evident when grimy upper surface is removed. A good example is that of the famous historical monument ‘Taj Mahal’ at Agra, which, on account of reaction of Sulphur-di-oxide, emitted from neighbouring industries, with the limestone has slowly, started turning yellow. As a result, on Court’s directives, a number of measures have been taken to protect our national heritage monument e.g. closure of neighbouring heavy polluting industries, operation of only non-polluting vehicles like battery busses, tonga in the vicinity of Taj Mahal etc.

ii) Soil, vegetation and Animal Life: The presence of gaseous pollutants in the air and deposition of particulates on to the soil can effect plants. It can effect the cattle and animals too as they have been found to develop breathing difficulties and suffer from low yield of milk, lameness and joint stiffness in a polluted environment

iii) Human beings: Smoke and SO₂cause the general and most widespread effects of air pollution on people. Atmospheric smoke contains potentially carcinogenic organic compounds similar to those that occur in cigarette tobacco smoke. The CO affects the cardiovascular system, NO_xs affect the respiratory system, Ozone causes increased sensitivity to infections, lung diseases, irritation in eyes, nose and throat etc.

STEPS TAKEN SO FAR AND THEIR IMPACT

With the alarming increase in the atmospheric pollution, especially in the big cities, Government has taken some important initiatives in the recent years. To start with the emphasis and implementation has been primarily in the big cities but gradually to spread throughout the country. These relate to the progressive tightening of the auto-emission norms (1991,1996,1998 & 2000) and fuel quality specifications (1996) as recommended by the Central Pollution Control Board (CPCB).

Till early 1994 ambient air quality standards in India were based on 8 hourly average time only. In April, 1994, these standards were revised and 24 hourly standards were also prescribed. National ambient air quality standards are prescribed for three distinct areas viz. i) industrial, ii) residential, rural and other areas and iii) sensitive areas.

Following steps have been taken so far:

i) Unleaded Petrol: With the gradual reduction of lead content in petrol and finally supply of unleaded petrol for all vehicles from Sept. 1998 in the capital city of Delhi, a lethal pollutant from vehicular exhaust has been removed. The lead content in the atmosphere near traffic intersections of Delhi has reduced by more than 60% with this measure.

ii) Sulphur in diesel: The sulphur content in the diesel supplied in Delhi has been reduced from 0.5% in 1996 to 0.25% in 1997 so as to meet the EURO-II norms.

iii) Tightening of the Vehicular Emission Norms: From 1995 new passenger cars were allowed to register only if they were fitted with catalytic converters. Emission norms for such cars were tightened by 50 % as compared to 1996 norms. With the recent directions of the Hon’ble Supreme Court, passenger cars ( both petrol and diesel) are required to meet atleast EURO-I norms in June 1999 and from Apr. 2000 only such vehicles meeting EURO-III norms will be permitted to register in the NCR of Delhi. CNG operated vehicles are also permitted by the Supreme Court directions.

iv) 2-T Oil for Two stroke engines: From 1.04.99, on the recommendations of CPCB, the low smoke 2T oil became effective. To prevent the use of 2T oil in excess of the required quantity, premixed 2T oil dispensers have been installed in all the petrol filling stations of Delhi. Sale of loose 2T oil has also been banned from Dec. 1998.

v) Phasing out of Grossly Polluting Vehicles: On CPCB’s recommendations initially 20 yr. Old vehicles were prohibited from plying from Dec.1998, followed by phasing out of 17 yr. old vehicles from Nov.98 and 15 yr. old from Dec. ’98.

IMPACT ON POLLUTION LOAD AND AIR QUALITY IN DELHI

The major impacts have been observed through the implementation of emission norms and fuel quality specifications effective from 1996, as also phasing out of 15 year old commercial vehicles and leaded petrol in the year 1998 and phasing out of 8 year old commercial vehicles and 15 year old two wheelers from 2000 onwards. The ambient air quality as monitored by CPCB during 1999, shows reduction in levels of various pollutants in ambient air as compared to previous year. The reducing trend was observed with respect to Carbon Monoxide, nitrogen dioxide, and lead in residential areas.

NOISE POLLLUTION

Of late, noise has been recognized as a pollutant which until recently was considered only as a nuisance. The Central Pollution Control Board (CPCB) has notified the ambient noise standards in 1987 under section 20 of the Air (Prevention and Control of Pollution ) Act, 1981. The noise standards specify limits as 55dB(A) and 45dB(A) as limits for day and night time respectively for residential areas, 75 dB(A) and 70 dB(A) in the day and night time for industrial areas, and 50 dB (A) and 40 dB(A) in the day and night for silence zones. Special campaign for reduction in use of fire crackers in Delhi have resulted in reduced pollution levels during Diwali in 1999.

4.2 GREEN HOUSE GASES AND THEIR EFFECTS

The greenhouse effect plays a crucial role in regulating the heat balance of the earth. It allows the incoming short-wave solar radiation to pass through the atmosphere relatively unimpeded; but the long-wave terrestrial radiation emitted by the earth’s surface is partially absorbed and then re-emitted by a number of trace gases in the atmosphere. These gases known as GHGs (greenhouse gases) are: water vapor, carbon dioxide, methane, nitrous oxide and ozone in the troposphere and in the stratosphere. This natural greenhouse effect warms the lower atmosphere.

If the atmosphere were transparent to the outgoing long wave radiation emanating from the earth’s surface, the equilibrium mean temperature of the earth’s surface would be considerably lower and probably below the freezing point of water. Mere incidence of GHG’s in the atmosphere, by itself, is no concern. What is more important is that their concentration should stay within reasonable limits so that global ecosystem is not unduly affected. However, by increasing the concentrations of natural GHG’s and by adding new GHG’s like chloroflouro carbons the global average and the annual mean surface-air temperature (referred to as the global temperature) can be raised, although the rate at which it will occur is uncertain. This is the enhanced greenhouse effect, which is over and above that occurring due to natural greenhouse concentration. Such a rise in the atmospheric concentration of GHG’s has led to an upward trend in global temperature.

While it is required to follow the general commitments under the Framework Convention on Climate Change, India is not required to adopt any GHG reduction targets. Irrespective of international commitments, it seems prudent to ready with

· Inventory of sinks & sources of GHG emission

· Predict the cumulative impact of national and international GHG emissions to plan for temperature and sea level rise

· Devise landuse plans for the coastal areas likely to be affected

· Devise water & land management strategies especially agricultural sector

LIST OF TABLES