Steep drop in pollution since janta curfew, lockdown

Since the janta curfew was announced on March 22 and the country-wide lockdown two days later, particulate matter concentration in the Capital showed a significant fall, according to a central pollution control board (CPCB) report.

Between March 22 and 23, PM10 concentration(coarse pollution particles with diameter less than 10 microns) fell by 44%, while that of PM2.5 (ultra fine particles) fell by 8% from peak values recorded on March 21. After lockdown, PM2.5 levels fell by 34%.

While the March 22 curfew was a voluntary event on a Sunday, orders from the Delhi government prior to it had already shut down most schools and gyms, and advised citizens to remain indoors as much as possible. On March 23, the Delhi government clamped a lockdown in the city shutting all but essential services.

The measures between March 22 and 23 are significant as there was a steep reduction in the number of vehicles on the road and aided by favourable weather.On the days, there was 51% drop in oxides of nitrogen (NOx)and 32% reduction in carbon monoxide (CO) levels compared to March 21.

CPCB analysed the trends based on hourly PM10, PM2.5, NOx and CO data in the national capital region. Its scientists said favourable meteorological factors like rain and moderate wind speed also helped with dispersal of pollutants.

“Air quality monitoring data reveal that during the lockdown period, PM10 and PM2.5 levels were reduced by about 35% to 40%, which may be explained as a possible reduction from industries (10% considering continued operation of power plants with 7% – 8% share), transport ( 15% with essential service vehicles and a small part of fleet still plying on roads), dust (10-15%; with continued contribution due to soil and wind-blown dust because of high surface winds),” the report reads.

Experts say the steep reduction could be because the country-wide lockdown cut off most sources of pollution not just in the city but surrounding areas as well.

“Janta curfew was only for a day when the PM level started dropping but the maximum effect of restrictions were seen during the lockdown. The question is how can we achieve similar air quality targets even after the outbreak resolves. We need systematic solutions that will help us to sustain this kind of air quality. Collective community action during this pandemic can help us to reinvent longer-term solutions to reduce our vulnerability to toxic risk,” said Anumita Roychowdhury, executive director, Centre for Science and Environment.