ENVIS Centre, Ministry of Environment & Forest, Govt. of India

Printed Date: Wednesday, December 11, 2019

Air Pollution

Air Pollution in Tamil Nadu
Introduction
          Air pollution is defined as the introduction of particulates, biological molecules, or other harmful materials into the Earth's atmosphere, possibly that cause disease, death to humans, damage to food crops, or the natural or built environment. 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. Indoor air pollution and urban air quality are listed as two of the world’s worst toxic pollution problems.
 
 Air pollution:-
 
1. The presence in the atmosphere
          In the atmosphere of one or more contaminants in such quality and for such duration as is injurious, or tends to be injurious, to human health or welfare, animal or plant life".  It is the contamination of air by the discharge of harmful substances.  Air pollution can cause health problems and it can also damage the environment and property.  It has caused thinning of the protective ozone layer of the atmosphere, which is leading to climate
 
2. 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.
 
2.1. Anthropogenic (man-made) sources
These are mostly due to the burning of multiple types of fuel. Anthropogenic sources include the following: 
  1. Stationary sources include stacks of power plants, manufacturing Factories, waste  incinerators, furnaces and other types of fuel-burning devices.
  2. In less developed countries traditional biomass burning is the major source of air  pollutants;Traditional biomass includes wood, crop waste and Cow-dung.
  3. Mobile Sources include vehicles, marine vessels, and aircrafts. Fumes from paint, hairspray, varnish, aerosol sprays and other solvents also contribute   towards air pollution.
  4. Waste deposition in landfills; generate methan during the breakdown of compounds.  Methane being highly flammable and forms explosive mixtures with air.
  5. Methane is also an asphyxiant and displaces oxygen in an enclosed space. Military resources, such as nuclear weapons and toxic gases are also key sources of air pollution. 
 
2.2. 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      Volcani 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 are        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.
 
3. 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.

 

4.  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.

 
5. 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. National Air Quality Monitoring Programme (NAMP)
 
Status of Air Quality of Important Cities/Towns of Tamil Nadu – Under National Air Quality Monitoring Programme (NAMP) Annual Average Concentrations of Air Pollutants, 2017– 2018
S.
No
 City & Location
 Category
Annual Average concentrations of Air Pollutants in µg/m3
SO
NO
PM10
PM2.5
Max
Min
Avg
Max
Min
Avg
Max
Min
Avg
Max
Min
Avg
  1
 CHENNAI
a)
Kathivakkam
Industrial
15
11
13
18
13
15
67
32
47
43
20
29
b)
Manali
Industrial
16
12
14
20
14
16
76
37
52
51
21
31
c)
Thirvottiyur
Industrial
15
11
13
18
13
15
72
36
52
-
-
-
d)
Anna Nagar
Residential
10
7
9
20
14
17
137
58
98
49
22
39
e)
Adyar
Residential
8
6
7
16
12
14
75
32
53
26
9
16
 2
 COIMBATORE
a)
SIDCO
Industrial
8
5
6
31
22
26
82
35
56
57
24
39
b)
Ponaiyarajapuram
Residential
6
4
4
29
19
23
70
28
46
45
19
32
  3
 THOOTHUKUDI
a)
Raja Agencies
Industrial
16
11
14
15
8
11
249
111
186
67
13
32
b)
SIPCOT
Industrial
16
11
13
12
7
10
189
66
122
84
16
38
3
 MADURAI
a)
M/S Susee Cars & Trucks (p) Ltd.,
Industrial
17
13
14
28
20
24
94
54
72
38
25
31
b)
Highways project Buildings
Residential
10
7
9
20
16
18
80
48
61
31
19
24
  4
CUDDALORE
a)
SIPCOT
Industrial
15
9
10
21
16
17
55
40
46
31
26
25
b)
Eachangadu Village
Residential
16
10
11
21
16
17
58
42
47
35
28
32
 5
METTUR
a)
SIDCO
Industrial
9
6
7
27
19
23
81
33
55
39
19
30
b)
Raman Nagar
Residential
8
6
6
25
17
20
55
25
35
29
16
21
 6
TRICHY 
a)
Golden Rock
Residential
13
10
11
21
17
18
80
44
59
51
22
35
Prescribed standards(Annual average) for Industrial, Residential, Rural & Other areas
50
40
60
40
Note: SO2 : Sulphur di Oxide NO2: Nitrogen di Oxides
PM10 : Particulate Matter (less than 10 micron size)
PM2.5: Particulate Matter (less than 2.5 micron size)
Source: TNPCB
 
 5.1 Chennai Ambient Air Quality Monitoring (CAAQM) Programme
 
            Under NAMP three ambient air quality monitoring stations are functioning on 24 hours basis, twice a week.  The samples collected from NAMP stations are analysed for the Total Suspended Particulate Matter (TSPM), Respirable Suspended Particulate Matter (RSPM).   (RSPM is particulate matter less than 10 microns) and gaseous pollutants such as Sulphur di oxide (SO2) and Oxides of Nitrogen (NOx).    
            Under CAAQM programme, TNPCB is operating five monitoring stations on 24 hours basis two stations per day on all working days. The pollutants measured in the CAAQM stations are Sulphur di oxide (SO2), Oxides of  Nitrogen (NOx), Respirable Suspended Particulate Matter (RSPM) and Total suspended particulate matter (TSPM) in all stations.
 
The eight ambient air quality monitoring stations in Chennai are:
Table 2. Ambient Air Quality Monitoring Stations
I
Kathivakkam (NAMP)
Industrial area
II
Manali (NAMP)
Industrial area
III
Thiruvottiyur (NAMP)
Industrial area
IV
Kilpauk (CAAQM)
Commercial (traffic inter-section
V
Thiyagaraya Nagar (CAAQM)
Commercial (traffic inter – section)
VI
Vallalar Nagar (CAAQM)
Commercial (traffic inter – section)
VII
Anna Nagar (CAAQM)
Residential area
VIII
Adyar (CAAQM)
Residential area
Source: Tamil Nadu Pollution Control Board
  • The ambient air quality data collected from the above mentioned air quality monitoring stations (NAMP) indicate that all the parameters such as sulphur di oxide, oxides of nitrogen, total suspended particulate matter and respirable dust particulates are found to be well controlled in the industrial area die to the effective monitoring of  industrial source emissions by the TNPCB.
  • In general, under CAAQM project the ambient air pollutants such as sulphur dioxide and oxides of nitrogen are well within the standards in Chennai city limit, where as total suspended particulate matter and respirable suspended particulate matter (PM) levels exceeded the permissible limit at all stations except Adyar mainly due to the dust contributed by pipe line, telephone/electrical cable laying activities on the road and also due to the resuspension of traffic dust generated from automobile emissions and heavy vehicular traffic and pedestrian movement.
 6.  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
  1. No new polluting units are permitted within the cit.
  2. No new incinerators are permitted within the city, old incinerators being phased out.
  3. Common facilities are set up outside the city for incineration of Bio-medical Waste.
  4. The industries have been directed to develop a green belt of minimum 33% of the project area.
  5. Green belt is also being developed by industries on road sides as avenue plantations.
  6. Renewal of the consent is based on compliance with this condition.
  7. Periodic inspection of industrial units is to be fitted with online stack  monitor connected to the pollution control board – CARE Air centre.
7)  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 in Chennai city for all vehicles from 1-1-1997.
  • Catalytic Converter fitted passenger car have been registered since, 1997.