Mumbai topped in reduction of pollutants among six cities

Mumbai has seen the sharpest reduction in harmful air pollutants during the lockdown among major Indian cities, said the System of Air Quality Weather Forecasting and Research (SAFAR) on Tuesday. Researchers compared a three-week average pollutant concentration between March 1 and 21 and March 23 and April 14 for six cities (Delhi, Pune, Ahmedabad, Kolkata, Chennai and Mumbai), using data from multiple monitoring stations including those of the Central Pollution Control Board, the American Consulate, and SAFAR’S own monitoring stations. The results were presented by Gufran Beig, director,

SAFAR, during a the Ministry of Earth Sciences’ webinar on Tuesday.

Between March and April, Mumbai saw maximum percentage reduction for nitrogen dioxide (NO2) and particulate matter (PM) 2.5 — among the six cities. Mumbai recorded a 76% decline in NO2 (mainly from automobile fuel burning) and a 54% reduction of PM2.5 concentration. Kolkata recorded a 67% decline in NO2 and 40% reduction in PM 2.5 concentration.

However, even without major industrial and automobile emissions, Mumbai’s lowest PM2.5 concentration (or background level) was 33 micrograms per cubic metre (µg/m³), which was the highest of the six cities. “Background levels are the permanent concentration in any city when anthropogenic emissions are at their lowest. This shows that even though Mumbai has high pollutant dispersion, its background air already has higher PM2.5 than other cities,” said Beig. The national safe standard for PM2.5 is 40 µg/m³ for 24 hours.“being a coastal city, Mumbai has the advantage of sea breeze resulting in faster dispersion of pollutants,” he said.

TRANSPORT ADDED MOST TO PM2.5 LEVELS SAFAR on Tuesday said that its emission inventory for PM2.5 in Mumbai’s air in 2019 found the transport sector was the most dominant source at 30.49%. Sources titled ‘others’ (including open fires, brick kilns, textile plants, dust storms and sea salt) accounted for 20.88%.