Road dust and secondary particles emitted from various sources are the primary contributors of pollution in the national capital, according to a draft report by IIT Kanpur. While the pollutants are almost similar in both summer and winter, sources said vehicles are the major contributors to pollution during winter.
“During winter, one of the major pollutants is not dust but from secondary particles, which are especially emitted by vehicles,” said a source.
The main contributors for PM 10 and PM 2.5 during winter are trucks and two-wheelers. Other sources of pollution during winter include secondary particles (25-30 per cent), vehicles (20-25 per cent), biomass burning (17-26 per cent), MSW burning (9-8 per cent) and to a lesser extent soil and road dust. In winters, major sources for PM 10 and PM2.5 are generally the same.
According to the report, the four top contributors of PM 10 during summer are road dust, concrete batching plants, industrial point sources and vehicles. The top four contributors for PM 2.5 are dust, vehicles, domestic fuel burning and industrial pollution. Other sources of pollution in summer include coal and fly ash (37-26 per cent), road dust (26-27 per cent), secondary particles (10-15 per cent), biomass burning (7-12 per cent), vehicles (6-9 per cent) and MSW burning (8-7 per cent).
“Delhi has witnessed severe air pollution as far as PM 10, PM 2.5 and nitrogen oxides in ambient air are concerned. These do not pollute in solitude but carry other pollutants,” said a source.