Chennai: If you are of the opinion that the Covid-19 induced lockdown has brought down pollution levels, sorry, you might be wrong.
For, a study of summer air quality trends during the nationwide lockdown, which started on 25 March, 2020, reveals that while PM2.5 (particulate matter) and NO2 (nitrogen dioxide) levels fell and flattened in many cities, tropospheric ozone pollution increased and even breached standards in several cities.
The analysis was conducted by the Centre for Science and Environment (CSE) in 22 mega and metropolitan Indian cities, including the National Capital Region, Kolkata, Kochi and Lucknow.
Based on data from the Central Pollution Control Board’s (CPCB) official online portal, the Central Control Room for Air Quality Management, the research said that that even as blue skies emerged in most cities (as particulate matter and NO2 levels plummeted) invisible ozone raised its ugly head on several days and in several cities.
According to Anumita Roychowdhury, executive director-research and advocacy, CSE, “This pandemic-led change in air quality has helped us understand summer pollution. Normally, every year, winter pollution is what draws our attention. The characteristics of summer pollution are different: there are high winds, intermittent rains and thunderstorms, and high temperature and heat waves. This is in contrast to winter— with its inversion, lower mixing height of air, and cold and calm conditions that trap the air and the pollutants in it.”