Amid the coronavirus lockdown, countries across the globe have reported a significant drop in air pollution and witnessed improved air quality.

According to the World Air Quality Index, countries like the United States, Spain, Italy, China, France, Mexico and the UK have reported a drop in the level of NO2 levels in April as compared to the same period last year, the most significant improvement in air quality was seen in New Delhi.

Amid the lockdown, India’s national capital reported a drop in its NO2 levels. Nitrogen dioxide or NO2 is a gas emitted by motor vehicles and factories mostly and therefore, a drop in its level is indicative of reduced human activity outside the home amid the coronavirus lockdown.

As per an analysis by experts at the nonprofit Center for Science and Environment, days after the coronavirus lockdown was put into force on March 25 in India, the level of particle pollution dropped by nearly 60% in New Delhi.

But experts worry the clean air and unsullied skies are not here to stay once the lockdown is lifted. Selected business and economic activities resumed across the country on April 20. While the Delhi administration decided to provide no relaxation in lockdown restrictions in the national capital, some neighbouring states lifted few curbs.

Experts fear that a return to the pre-lockdown situation, where factories resume operations and vehicles jam the roads again, pollution levels will rise again.

“Currently, we have clean air due to the lockdown but this respite is short term. After the restrictions are lifted and human activities start, there will be a sudden rise in air pollution,” TK Joshi, member, Central Pollution Control Board (CPCB) task force on air pollution and health told HT’s business publication Mint.