Half of PM 2.5 pollution in Delhi around Diwali was from vehicles: Report

Vehicular emission contributed half of PM 2.5 pollution from local sources in Delhi during the Diwali week between October 21 and October 26, according to the latest assessment by the Centre for Science and Environment (CSE).

It said that when pollution concentrations from all sources -- local, NCR and beyond -- are added, Delhi's vehicles account for nearly 17 per cent of total PM2.5 concentration. But, according to CSE's indicative data, vehicles' daily share of pollution varied between 49.3 per cent and 53 per cent during the week of Diwali.

"The vehicular contribution was followed by household pollution (residential) at 13 per cent, industries at 11 per cent, construction at 7 per cent, waste burning and the energy sector at 5 per cent each, and road dust and other sources at 4 per cent each. This observation is consistent with the trends evaluated during the previous winter in Delhi," principal programme manager at CSE's Clean Air and Sustainable Mobility unit Vivek Chattopadhyay said.

The CSE report indicated all combustion sources, including vehicles, peripheral industries, the energy sector, waste burning and residential cooking, have a higher share than the dust sources that include construction and road dust.

The report has used the decision support system (DSS) of Indian Institute of Tropical Meteorology(IITM), which has provided the information on potential emission sources in Delhi.

"With high traffic on pre-Diwali days, average speed plummeted to 27 km per hour against the design standard of 60 km per hour or regulated speed of 40 km per hour. On some stretches this reduced to 17 km per hour. Nitrogen dioxide coming largely from vehicles correlates well with traffic peaks and congestion though dispersion helped to dilute it in the afternoons, the CSE assessment stated.

The organisation said that despite vehicles becoming the top polluter, action on transport remains "the weakest".

It further stated that public transport augmentation and integration is needed, along with electrification of fleet, walking and cycling infrastructure, low emissions zones and vehicle restraint measures such as parking caps and pricing.