Delhi: Road-dust and fly-ash bigger summer pollutants, says study

DELHI: As the odd-even scheme’s second phase faced a stern test on Monday, critics and skeptics of the scheme have once again pointed that the focus of the initiative has shifted from reducing pollution to decongestion of road traffic. This, critics have said, has led to sidelining of holistic measures needed to reduce other major sources of pollution such as road dust, industries and domestic sources.

Though there have been several studies in the past on the major sources of pollution in the capital, the last comprehensive study on this issue, carried out by Indian Institute of Technology-Kanpur, has clearly shown that road dust and not vehicular pollution is the biggest source of air pollution. According to the IIT-Kanpur study that was carried out between 2012 and 2015, road dust is the top contributor to both PM10 (particulate matter) and PM2.5 emissions in Delhi.

Particles with a diameter of 10mm or less are called PM10 and those with a diameter of less than 2.5mm are called PM2.5. These fine particles when ingested by our respiratory organs pose health hazards and respiratory disorders.

Followed by road dust, vehicular pollution, domestic fuel burning and industries are the biggest sources of PM2.5 pollution. The report though, also says that the two most consistent sources for PM10 and PM2.5 pollution in both winter and summer seasons are secondary particles and vehicles. In fact, among vehicles, trucks contribute 46%, the maximum, to air pollution followed by two-wheelers that contribute 33% while four-wheelers contribute 10%.

In summer, coal and fly ash contribute about 30 per cent of PM10 and unless sources contributing to fly ash are controlled, one cannot expect improvement in air quality, the report said. Delhi is home to two coal-fired power plants at Rajghat and Badarpur of which the Rajghat plant has been shut down while two of the five units at the Badarpur plant continue to operate. Delhi also has nearly 9,000 restaurants which use coal in tandoors and they are one of the biggest sources of fly ash emissions, the report had said.

Biggest contributors to Delhi pollution (source: IIT-Kanpur study)
Road dust: 38%

Vehicle: 20%

Domestic: 12%

Industrial stack: 11%

Concrete batching: 6%

Biggest sources of PM10 and PM2.5 pollution in summer (Source: IIT-Kanpur study)
Coal and Flyash: 37-26%

Soil and road dust: 26-27%

Secondary particles: 10-15%

Biomass burning: 7-12%

Municipal solid waste burning: 8-7%