Delhi air pollution: City’s ‘dust’ screen hiding bigger killers

New Delhi: Dust may be the most visible marker of Delhi’s air pollution, but its sheer abundance may actually be masking the bigger killers – emissions from vehicles, thermal power plants and industries.
Studies and research reports have underlined that its the chemical composition of ultrafine particulates PM2.5 or PM10, and not their volume, which is more crucial in determining the toxicity of air.
The Environment Pollution (Prevention and Control) Authority (EPCA), a Supreme Court-appointed pollution watchdog, made a similar point in a report the apex court, that particles from coal and diesel are more harmful than wind-blown dust, as they can lead to an increase in heart disease-related deaths.
“Similarly, particles from diesel combustion are very toxic and have been classified by the World Health Organisation as a class I carcinogen for strong links with lung cancer, putting them in the same bracket as tobacco smoking and asbestos.
“This suggests that we must prioritise the more harmful particulates for action. Combustion sources – vehicles, power plants and industry – need more stringent and priority action,” the report says. The EPCA mentioned it separately under a section – addressing quantum vs toxicity.
An Indian Institute of Technology-Kanpur report, which assessed the chemical composition of pollution from various sources in the city, also concluded that combustion – vehicular and industrial alike – was responsible for the formation of PM2.5 in greater quantity.
Among PM2.5 and PM10, the most dominant pollutants in Delhi’s air, PM2.5 is deadlier owing to its tinier size – up to 30 times smaller than the width of a human hair – aiding it in lodging deep in the lungs and subsequently entering the bloodstream.
The IIT report found that PM2.5 Nitrate particles formed from nitrogen oxides and sulphate particles formed from sulphur dioxides can be 25 per cent of the total PM2.5 load in the city.