delhi

Updated: Jan 18, 2011 02:02 IST

A new government study has broken the popular belief that vehicles are the major source of Particulate Matter (PM) air pollution. Instead, industrial emissions and road dust are the prominent causes, says environment ministry’s Source Appropriation Study in seven big cities of India.

Particulate matter was the fastest growing pollutant in most Indian cities but its sources were not known.

The only study of its type, first reported by HT in June 2010 and reviewed by an inter-ministerial group said that vehicles are the highest contributor to PM 10 (particulate matter of 10 micros or more) levels only in Bangalore. They were found to be third or fourth contributor in the remaining six cities, Delhi, Mumbai, Chennai, Pune, Kanpur and Chennai.

“Despite the large fleet of vehicles in Delhi, the share is less due to presence of other significant sources such as power plants, road dust re-suspension,” the report vetted by air pollution experts in Europe and United States, said.

Vehicular contribution to PM pollution was only seven percent whereas road dust contributed about 50% to total PM 10, which was found to be highest in Delhi among the cities surveyed.

Road dust re-suspension is primarily because of undone payments, roadside eateries and construction activity without pollution control measures.

Industrial activity was found to be the highest contributor for PM 10 pollution, which triggers lung ailments, in Mumbai and Kanpur. Large industries were the cause in Mumbai whereas small-scale industries produce high particulate matter in Kanpur. Power plants within city boundary limits were the primary cause for industry contributing 22 % in Delhi.

The study also found that domestic use of Liquid Petroleum Gas (LPG) was also a cause for particulate matter pollution. Including PM 2.5, a fine pollutant whose repeated exposure can trigger heart attacks.

Another startling revelation was that vehicles are not the major contributor to nitrogen oxide (NOX) pollution in Delhi and Mumbai. The fumes from diesel vehicles were considered the major source of rising levels of this gaseous pollutant in Delhi, where industries have been blamed for his high concentration.

However, the study found that in transport sector heavy-duty vehicles, especially those running on diesel, were the biggest contributor to pollution levels.