» Trends in SO2

Trend in annual average concentration in SO2 levels in Delhi, Mumbai, Chennai and Kolkata is depicted in Figure 1. Trend in annual average concentration in SO2 levels in Hyderabad, Bangalore, Ahmedabad and Pune is depicted in Figure 2. Trend in annual average concentration in SO2 levels in Kanpur, Lucknow, Varanasi and Agra is depicted in Figure 3. Trend in annual average concentration in SO2 levels in Jodhpur, Patna, Faridabad, Solapur and Jharia is depicted in Figure 4. A decreasing trend has been observed in sulphur dioxide levels in residential areas of cities like Delhi, Mumbai, Lucknow, 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.

» Trends in NO2

Trend in annual average concentration in NO2 levels in Delhi, Mumbai, Chennai and Kolkata is depicted in Figure 5. Trend in annual average concentration in NO2 levels in Hyderabad, Bangalore, Ahmedabad and Pune is depicted in Figure 6. Trend in annual average concentration in NO2 levels in Kanpur, Lucknow, Varanasi and Agra is depicted in Figure 7. Trend in annual average concentration in NO2 levels in Jodhpur, Patna, Faridabad, Solapur and Jharia is depicted in Figure 8. A decreasing trend has also been observed in nitrogen dioxide levels in residential areas of Solapur, Kolkata 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.

» Trends in RSPM

Trend in annual average concentration in RSPM levels in Delhi, Mumbai, Chennai and Kolkata is depicted in Figure 9. Trend in annual average concentration in RSPM levels in Hyderabad, Bangalore, Ahmedabad and Pune is depicted in Figure 10. Trend in annual average concentration in RSPM levels in Kanpur, Lucknow, Varanasi and Agra is depicted in Figure 11. Trend in annual average concentration in RSPM levels in Jodhpur, Patna, Faridabad, Solapur and Jharia is depicted in Figure 12. 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 despite steep increase in number of vehicles.