Findings

The ambient air quality data is available in Environmental Data Bank software.

» Sulphur dioxide

· The levels of sulphur dioxide are within the prescribed National Ambient Air Quality Standards.

· A decreasing trend has been observed in sulphur dioxide levels in residential areas of cities like Delhi, Mumbai, Lucknow, Bhopal etc., during last few years. The decreasing trend in sulphur dioxide levels may be due to various measures taken such as reduction of sulphur in diesel etc. and use of LPG instead of coal as domestic fuel. Also, conversion of diesel vehicles to CNG may have contributed to reduction in ambient SO2 levels

» Nitrogen dioxide

· The levels of nitrogen dioxide are within the prescribed National Ambient Air Quality Standards in most of the cities.

· A decreasing trend has also been observed in nitrogen dioxide levels in residential areas of Bhopal, Solapur etc. during last few years. The decreasing trend in nitrogen dioxide levels may be due to various measures taken for vehicular pollution control such as stricter vehicular emission norms etc. Vehicles are one of the major sources of NO2 in the country. Trend in ambient NO2 is fluctuating in many cities despite steep increase in number of vehicles.

» Respirable Suspended Particulate Matter

· The levels of RSPM exceed the prescribed National Ambient Air Quality Standards in most of the cities.

· One of the major source of high RSPM levels is vehicles. The vehicle population is increasing exponentially in many cities. This is the single major factor for high RSPM levels.

· A decreasing trend has also been observed in RSPM levels in cities like Solapur, Ahmedabad etc during last few years. Decreasing trend in RSPM levels may be due to various measures taken such as reduction of sulphur in diesel, stringent standard of particulate matter in diesel vehicles etc. Trend in ambient RSPM is fluctuating in many cities.

· The reason for high particulate matter levels may be vehicles, engine gensets, small scale industries, biomass incineration, boilers and emission from power plants, resuspension of traffic dust, commercial and domestic use of fuels, etc.

» Suspended Particulate Matter

· The levels of SPM exceed the prescribed National Ambient Air Quality Standards in most of the cities.

· Trend in SPM is fluctuating in many cities. The sources of SPM include, vehicles, natural dust, industries such as thermal power plants, sugar, cement etc., resuspension of dust, refuse burning etc. Trend in annual average concentration of SPM is fluctuating in many cities.

· Lower levels of RSPM and SPM were observed during monsoon months possibly due to wet deposition. Higher levels of RSPM were observed during winter months possibly due to lower mixing heights and more calm conditions.

» Non-attainment Cities

CPCB has identified list of polluted cities in which the prescribed National Ambient Air Quality Standards ( NAAQS) are violated. These cities have been identified based on ambient air quality data obtained under National Air Quality Monitoring Programme (NAMP). Action plans are being formulated and implemented to control air pollution in non-attainment cities by respective states.

LIST OF NON ATTAINMENT CITIES IN INDIA