Coronavirus: Mumbai witnesses 81% drop in NO2 levels in six weeks

A six-week assessment of air pollution data showed an 81% decline in nitrogen dioxide (NO2) levels in the air above Mumbai Metropolitan Region (MMR). This is the

A six-week assessment of air pollution data showed an 81% decline in nitrogen dioxide (NO2) levels in the air above Mumbai Metropolitan Region (MMR). This is the first air quality assessment using satellite imagery since a lockdown imposed to contain the spread of the Sars-Cov-2 virus.

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“The absence or reduction of almost all major sources of air pollution led to a drastic drop in emissions [during the lockdown], which shows that the air can be cleaned if emissions are controlled. Clean air does not necessarily have to come at the cost which we are paying now due to the Covid-19 outbreak, but this crisis should be used as an opportunity to learn from and move forward,” said Sunil Dahiya, an analyst working with Centre for Research on Energy and Clean Air (CREA).

CREA’s assessment showed an 81% decline in NO2 levels over six weeks, based on the Central Pollution Control Board’s (CPCB) readings across 10 real-time stations in Mumbai, and satellite imagery (TROPOMI/S5P satellite data). The most significant fall in NO2 levels was witnessed between March 23 and 29 when the concentration dropped to 10 µg/m3 and satellite images showed almost no emissions over most of MMR. The daily average on March 29 was 8 µg/m3, the lowest of this year so far, against NO2’s safe limit of 80 µg/m3.