Air quality in five major cities of India induced by the COVID-19 pandemic lockdown

Abstract

This discussion paper looks into the COVID-19 induced lockdown on the air quality of the five most polluted cities in India. There were significant reductions in the concentrations of particulate matter, 2.5 mm and 10 mm, NO2, and CO during lockdown compared to that in 2019. Even then, the levels of particulate matter never reached the target specified by the World Health Organization. There was an increase in the concentrations of O3 at some cities, which may be attributed to the alterations in the photostationary cycle due to change in the concentration of nitrogen oxides and volatile organic carbons.