AIR POLLUTION
Introduction
Air pollution is contamination of the indoor or outdoor environment by any chemical, physical or biological agent that modifies the natural characteristics of the atmosphere. Stratospheric ozone depletion due to air pollution has long been recognized as a threat to human health as well as to the Earth's ecosystems.
Air quality is closely linked to the earth’s climate and ecosystems globally. Many of the drivers of air pollution (i.e. combustion of fossil fuels) are also sources of greenhouse gas emissions. Policies to reduce air pollution, therefore, offer a win-win strategy for both climate and health, lowering the burden of disease attributable to air pollution, as well as contributing to the near- and long-term mitigation of climate change.
Types of Air Pollutants
Pollutants can be classified as either primary or secondary. Air pollutants are emitted from anthropogenic and natural sources, both either emitted directly (primary pollutants) or formed in the atmosphere (as secondary pollutants). They are produced on a local scale and it can be transported or formed over long distances and it affects ecosystems, climate and health at small or large areas.
1.Primarily Pollutants
Emitted directly into the air from sources. A classic example of a primary pollutant would be the sulfur-dioxide emitted from factories. Examples: CO, NOx, SO , Pb, SPM, RSPM, 2 VOCs.
2.Secondary Pollutants:
Pollutants which are formed from primary pollutants in the atmosphere. Some of the reactions are catalyzed by sun light. Examples: acid rains, smog, O, HO, formaldehyde, 3 2 2 peroxy acetyl nitrate (PAN).
Causes of pollution
There are various activities or factors which are responsible for releasing pollutants into the atmosphere. These sources can be classified into two major categories.
i. Anthropogenic (man-made) sources
ii. Natural sources
i. Anthropogenic (man-made) sources
These are mostly due to the burning of multiple types of fuel. Anthropogenic sources include the following:
- Stationary sources include stacks of power plants, manufacturing Factories, waste incinerators, furnaces and other types of fuel-burning devices.
- In less developed countries traditional biomass burning is the major source of air pollutants; Traditional biomass includes wood, crop waste and Cow-dung.
- Mobile Sources include vehicles, marine vessels, and aircrafts. Fumes from paint, hairspray, varnish, aerosol sprays and other solvents also contribute towards air pollution.
- Waste deposition in landfills; generate methan during the breakdown of compounds. Methane being highly flammable and forms explosive mixtures with air.
- Methane is also an asphyxiant and displaces oxygen in anenclosed space. Military resources, such as nuclear wepons and toxic gases are also key source of air pollution.
ii. Natural sources
* Dust from natural sources, mostly large areas of land with few or no vegetation. Radongas from radioactive decay within the Earth's crust. Radon is a naturally occurring, radioactive noble gas that is formed from the decay of radium. It is considered to be a health hazard.
* Radon gas from natural sources can accumulate in buildings; especially in confined areas is the one of the most frequent cause of lung cancer. Smoke and carbon monoxide from wildfires volcanic activity, produces sulfur, chlorine, and ash particulates.
* A pollutant can be of natural origin or man-made. Pollutants are classified as primary or secondary Primary pollutants are usually produced from a process, such as ash from a volcanic eruption.
* Other examples include carbon monoxide gas from motor vehicle exhaust, or the sulfur dioxide released from factories secondary pollutants are not emitted directly.
* Rather, they form in the air when primary pollutants react or interact. Ground level ozone is a prominent example of a secondary pollutant. Some pollutants may be both primary and secondary: they are both emitted directly and formed from other primary pollutants.
* In India the Major source of air pollution include Fuel wood and biomass burning in rural and urban India, Most of India uses Fuel wood and biomass cakes for cooking and general heating needs.
* Cook stoves using biomass are present in over 100 million Indian households and used two to three times a day. Majority of Indians still use traditional fuels such as dried cow dung, agricultural wastes, and firewood as cooking fuel.
Major primary pollutants produced by human activity include
a) Sulphur oxides (SOx)
Particularly sulfur dioxide, a chemical compound with the formula SO2 is produced by volcanoes and various industrial processes.
Coal and petroleum often contain sulfur compounds, and their combustion releases sulfur dioxide. Further oxidation of SO2, usually in the presence of a catalyst such as NO2, forms H2SO4, and leads to the formation of acid rain.
b) Nitrogen oxides (NOx)
Nitrogen oxides, particularly nitrogen dioxide, are expelled from high temperature combustion, and are also produced during thunderstorms by electric discharge. It is a chemical compound with the formula NO2. It is one of the most prominent air pollutants.
c) Carbon monoxide (CO)
CO is also a toxic gas. It is a product by incomplete combustion of fuel such as natural gas, coal or wood. Vehicular exhaust is a major source of carbon monoxide.
d) Volatile organic compounds
VOCs are a well-known outdoor air pollutant. They are categorized as either methane (CH4) or non-methane (NMVOCs). Methane is a greenhouse gas which has contributed to enhance global warming. The aromatic NMVOCs such as benzene, toluene and xylene are suspected carcinogens and may lead to leukemia with prolonged exposure.
e) Particulate Matter
Particulates, alternatively referred to as particulate matter (PM), atmospheric particulate matter, or fine particles, are particles of solid or liquid suspended in a gas. Aerosols In contrast, aerosol refers to combined particles and gas. They can occur naturally, from volcanoes, dust storms, forest fires, and sea spray. Human activities, such as the burning of fossil fuels in vehicles, power plants and industrial processes also generate significant amounts of aerosols.
f) Chlorofluorocarbons (CFCs)
Harmful to the ozone layer. These are gases which are released from air conditioners, refrigerators. CFC's on being released into the air rises to stratosphere and reacts with other gases and damage the ozone layer. This allows harmful ultraviolet rays to reach the earth's surface causing skin cancer and diseases to the eye.
Secondary Pollutants Include
Particulates created from gaseous primary pollutants are called secondary pollutants. Smog is a kind of secondary air pollution. Smog results from large amounts of coal burning in an area caused by a mixture of smoke and sulfur dioxide. Smog also comes from vehicular and industrial emissions that are acted on in the atmosphere by ultraviolet light from the sun to form secondary pollutants that also combine with the primary emissions to form photochemical smog.
a) Ground level ozone (O3)
It is formed from NOx and VOCs. Ozone (O3) is a key constituent of the troposphere. It is also an important constituent of certain regions of the stratosphere commonly known as the Ozone layer.
b) Peroxyacetyl nitrate (PAN)
It is also formed from NOx and VOCs.
Air Pollution in Tamil Nadu Scenario
Air quality is being monitored by the Tamil Nadu Pollution Control Board (TNPCB) to assess the concentration of air pollutants arising out of emissions from industries as well as increasing vehicular population. In Chennai alone, ambient air quality is being monitored at three locations under National Air Quality Monitoring Programme (NAMP) and at five locations under Chennai Ambient Air Quality Monitoring Programme (CAAQM). Apart from Chennai, monitoring of ambient air quality is carried out at Thoothukudi, Coimbatore, Madurai, Salem and Tiruchirapalli. Besides, six continuous ambient air quality monitoring stations are established at Cuddalore, Tuticorin, Ranipet, Manali-Chennai, Tamil Nadu Scenario. Royapuram- Chennai, Kottivakkam - Chennai to evaluate the levels of pollution. There has been a rapid increase in the number of vehicles, as a result of urbanization, economic growth and easy availability of finance. Apart from new vehicles, old vehicles also exist often with outdated technology and nonobservance of emission norms. The quality of fuel supplied has also compounded the problem of vehicular pollution. The Board is monitoring vehicular emission since 1992. In Chennai city, three vehicular monitoring stations located at Alandur, Ambattur and Vyasarpadi for monitoring of the vehicular emission from goods and transport vehicles on a continuous basis. In addition to this, vehicular emission is being monitored at Dindigul, Palani, Ooty, Chengalpattu and Katteri.
Strategies and Actions taken for controlling Air Pollution in Tamil Nadu
Government of Tamil Nadu faces to deterioration of air quality in view of it being a rapidly industrialising State which is also the most urbanised State in the country. There are several industrial clusters within the State in which air pollution is emerging as a concern, even as growth in personalised transportation contributes to degradation of air quality in urban areas. Along with these challenges, the expected increase in thermal power generation to meet the growing power demand makes it necessary to accord greater focus and thrust on minimizing risks of air pollution.
Government of Tamil Nadu would undertake the following actions in Air pollution Strengthen systems for monitoring air quality Continuous Emission Monitoring Systems (CEMS) shall be implemented in all industry clusters, thermal power plants and urban areas.
Urban air quality monitoring
a) The Tamil Nadu Pollution Control Board (TNPCB) monitors ambient air quality at 28 stations in major cities and towns under National Ambient Air Quality Monitoring Programme (NAAQMP) Tamil Nadu. These cities include Chennai (Eight stations), Coimbatore (Three stations), Thoothukudi (Three stations), Madurai (Three stations), Salem (One station), Trichy (Five stations), Cuddalore (Three stations) and Mettur (Two stations). This network shall be expanded to monitor air quality in all large urban agglomerations with population greater than 5,00,000.
b) Continuous air quality monitoring for industry areas and thermal power plants: In order to monitor source emissions and ambient air quality on a real-time basis, TNPCB has established a Centre for Accessing Real Time Air Quality Information Report (CARE AIR) at its Head office. A first-of-its-kind in the country initiative, CARE AIR is a continuous real-time emission monitoring system in which when emission levels exceed norms, an in-built alarm system is activated to inform concerned industry and environment officials.
Promote use of public transportation in urban areas
Government of would initiate projects and programmes to increase the share of public transport in urban commuting. The Integration of Multi modal transport system including metro, mono-rail, bus rapid transit with cycle tracks and walk ways shall be implemented wherever necessary in the State. Government of Tamil Nadu had made necessary amendments in the Tamil Nadu Motor Vehicle Rules 1989 to get Pollution under Control (PUC) certificate for goods vehicles in Chennai from authorized private testing centres. This initiative will be launched in other large urban centres (with population greater than 500,000).
Enforce legislation, policies, and rules to establish and meet air quality standards with focus on reducing Tamil Nadu industrial air pollution. Government of Tamil Nadu will ensure appropriate siting of industries and will strengthen enforcement mechanisms to control pollution from industries. Thrust shall be given to cleaner technologies, use of cleaner fuels and energy efficient devices.
Status of Air Pollution Tamil Nadu
Tamil Nadu Pollution Control Board is operating eight ambient air quality monitoring stations in Chennai under two monitoring programmes.
Table 1.Status of Air Quality of Chennai City of Tamil Nadu, Residential Report-2021
|
State
|
District
|
Location
|
Month
|
SO 2
|
NO 2
|
SPM
|
RSPM
|
|
Tamil Nadu
|
Chennai
|
Anna nagar
|
January
|
12
|
23
|
76
|
NA
|
|
February
|
10
|
22
|
NA
|
62
|
|
March
|
11
|
21
|
NA
|
58
|
|
April
|
11
|
21
|
52
|
NA
|
|
May
|
8
|
17
|
NA
|
39
|
|
June
|
9
|
18
|
NA
|
40
|
|
July
|
11
|
20
|
NA
|
51
|
|
August
|
10
|
21
|
NA
|
50
|
|
September
|
11
|
21
|
NA
|
53
|
|
October
|
10
|
21
|
NA
|
50
|
|
November
|
10
|
20
|
NA
|
49
|
|
December
|
10
|
21
|
NA
|
57
|
|
Adayar
|
January
|
10
|
20
|
NA
|
49
|
|
February
|
10
|
21
|
NA
|
52
|
|
March
|
10
|
21
|
NA
|
51
|
|
April
|
10
|
19
|
NA
|
45
|
|
May
|
7
|
16
|
34
|
NA
|
|
June
|
8
|
16
|
NA
|
35
|
|
July
|
10
|
19
|
NA
|
44
|
|
August
|
10
|
19
|
NA
|
45
|
|
September
|
10
|
20
|
NA
|
45
|
|
October
|
11
|
20
|
NA
|
48
|
|
November
|
9
|
19
|
NA
|
47
|
|
December
|
10
|
21
|
NA
|
54
|
Source: ISBEID –TNPCB.
Action Taken to Prevent Air Pollution in Tamil Nadu
a) Industrial Pollution
The salient features of actions taken to control industrial pollution are as follows
· No new polluting units are permitted within the cit.
· No new incinerators are permitted within the city, old incinerators being phased out.
· Common facilities are set up outside the city for incineration of Bio-medical Waste.
· The industries have been directed to develop a green belt of minimum 33% of the project area.
· Green belt is also being developed by industries on road sides as avenue plantations.
· Renewal of the consent is based on compliance with this condition.
· Periodic inspection of industrial units is to be fitted with online stack monitor connected to the pollution control board – CARE Air centre.
b) Vehicular Pollution
The salient features of action taken to control vehicular pollution are as follows
- Bharat Stage –II norms have been implemented for the registration of new passenger car from 1-7-2011.
- Emission norms for in-use vehicles in consultation with MoRTH & MoEF have been implemented.
- Catalytic Converter fitted passenger car have been registered.
Conclusion
Air pollution can be prevented the using toxic substances that cause air pollution in the first place. This would require the cessation of all fossil fuel-burning processes, from industrial manufacturing to home use of air conditioners. The regulations are to be designed to further reduce harmful emissions into the Earth's atmosphere.