Air Pollution

With a view to ascertain the ambient air quality at various locations, a monitoring
network has been established comprising of 295 stations covering 98 cities/towns in 29 States
and three Union Territories under the Air (Prevention and Control of Pollution) Act, 1981, as
amended in 1988. Under this programme, four criteria air pollutants viz. Sulphur dioxide
(SO2), oxides of nitrogen (NOx), Suspended Particulate Matter (SPM) and Respirable
Suspended Particulate Matter (RSPM) are regularly monitored at all the locations. Besides
this, additional parameters such as respirable lead and other toxic trace matters and polycyclic
aromatic hydrocarbons are also being monitored in 10 metro cities of the country. The
ambient air quality is monitored by Central Pollution Control Board (CPCB) in coordination
with the State Pollution Control Boards, Pollution Control Committees and some of the
universities and research institutes. The data, thus generated, are transmitted to CPCB for
scrutinisation, analysis, compilation and publication as a consolidated report. The monitoring
results indicate that levels of Sulphur dioxide and Nitrogen dioxide are within the stipulated
standards, whereas the levels of SPM and RSPM occasionally exceed, especially in Central
and Northern parts of the country due to natural dust and vehicular emissions.
The air quality of different cities/towns for three critical pollutants has been compared
with the respective national ambient air quality standards and has been classified into four
broad categories based on an Exceedence Factor (EF) as calculated by the following ratio:
Observed Annual mean
Concentration of criteria pollutant
Exceedence Factor =
Annual standard for the Respective
pollutant and area class
The four air quality categories are :
Critical pollution (C) : When EF is more than 1.5
High pollution (H) : When the EF is between 1.0-1.5
Moderate pollution (M) : With and EF between 0.5-1.0
Low pollution (L) : Where the EF is less than 0.5
Based upon the indicators stated above, a quarterly report is compiled by CPCB in some
of the major cities. For real time data collection, automatic monitoring stations have also been
established. Under the Male declaration, 11 automatic monitoring stations are also planned at
strategic locations to measure the trans-boundary movement of pollutants among the South
Asia Association of Region Co-operations (SAARC) Countries. CPCB has also initiated indepth
studies in the cities of Delhi and Kanpur to measures the level of PM10 and PM2.5.
To regulate and control air pollution, the source specific standards are notified from time
to time. During the year 2002, emission standards for new diesel generator sets upto 800 KW
were notified on 17th May, 2002 vide GSR 371(E). These rules shall apply to all new diesel
engines for Gensets manufactured in India or imported into India after the effective date. All
engines upto 20 KV shall carry ISI mark and meet the relevant BIS specifications. Emission
standards for diesel generator sets of more than 800 KW had also been notified on 9th July,
2002 vide GSR 489(E). These standards shall be regulated by the State Pollution Control
Boards or Pollution Control Committees as the case may be. It has also been made mandatory
for all the diesel generator sets upto 800 KVA or more to use the liquid fuel specified for
commercial. High Speed Diesel (HSD) applicable for diesel vehicles in the area from time to
time.