If the low levels air pollution reached during the lockdown period are maintained, India’s annual death toll could reduce by 6.5 lakh, says a study by the Indian Institute of Technology (IIT) Delhi, and two Chinese universities, Fudan University in Shanghai and Shenzhen Polytechnic.

As India went into the world’s biggest lockdown to combat the deadly coronavirus, trains, planes, automobiles and factories came to a halt. And the skies in some of the most polluted cities on the planet turned blue.

Cities across the country, which was home to 14 of the 20 most polluted cities in the world last year, are breathing some of the cleanest air after the lockdown came into effect.

Restricted economic activity during the first month of the lockdown, which was the most stringent, saw a 52% average reduction in excessive risk (health risk assessment due to air pollution exposure) for particulate matter (PM) across India. 

“If this low concentration during one month persisted for a year, it would save the lives of 6.5 lakh people, which would have otherwise been lost due to air pollution health effects,” said Sri Harsha Kota, corresponding author from IIT-Delhi.

In the latest study, researchers calculated the average annual concentration for previous years (2017 to 2019), compared it with the reduced average concentration during the lockdown, and analysed it for the rest of the year.

The pollutant measuring indicator – air quality index (AQI) – reduced by 30% pan-India, with a 44% drop in north India, 33% in the south, 32% towards the west, 29% for east, and 15% for central parts of the country, the study found.

“The results show that predicted PM2.5 could increase only by 33% during unfavourable weather. This means a significant improvement in air quality can be expected if strict execution of air pollution mitigation plans is implemented even if meteorological conditions are adverse,” said Kota.