NEW DELHI: There is a twist to the recent controversy about an MoEF affidavit to Supreme Court claiming vehicles in Delhi contribute to only 6.6% of particulate matter pollution while road dust contributes to 52%. Following criticism from experts about the veracity of these findings, MoEF, in another affidavit submitted to the apex court on Friday, claimed that vehicles in fact contribute between 8.7% and 20.5% of PM emissions while road dust leads to 14.5% to 29% and that the study by National Environmental Engineering Research Institute (NEERI) it had quoted is based on data from 2007.
The Central Pollution Control Board commissioned the NEERI study in 2005-06. Subsequent studies, some government-funded, have contradicted the NEERI findings of 6.6% PM emissions from the transport sector. NEERI scientists TOI spoke to were also clueless about why an old study was quoted in the affidavit and clarified it was not peer-reviewed.
In its latest affidavit, MoEF clarifies that its initial submission was only meant for PM10 (coarse particles more than 10 micrometres in size). PM10 emissions are not as dangerous as PM2.5 (fine, respirable particles less than 2.5 micrometres in size) as those can enter the bloodstream and get lodged in the lungs. It also informs that the data was from 2007 and there is no government study on source apportionment of PM2.5 emissions. A WHO study found Delhi has the highest PM2.5 levels among 1,600 cities globally. Delhi Pollution Control Committee has only recently commissioned another source apportionment study with focus on PM2.5 to Prof. Mukesh Sharma of IIT Kanpur.
After completely denying the role of vehicles in air pollution, MoEF-in its latest affidavit-seems to have made a volte-face. "Vehicular PM emissions being in the finer category and having toxic elemental carbon as well as organic carbon, controlling them is important for improving air quality and minimizing health effects." It also states there should be "no tolerance" to visible smoke-emitting vehicles and suggests taking Delhi government and the health ministry's opinion on mandatory use of masks, free public transport, allowing only BS III and BS IV vehicles and doubling of parking charges.
A NEERI scientist told TOI, "We aren't sure why MoEF quoted such an old study which only considers PM10 emissions. The study was not peer-reviewed." Another scientist said, "In any large city, contribution of vehicles is much higher. It's obvious the results of the NEERI study are not reliable."
CPCB had commissioned a large-scale study of health impacts of PM10 emissions to the Kolkata-based CNCI. Its 15-year study had alarming findings. Fearing criticism, CPCB reportedly didn't publish the reports for seven years.
