PU-PGI team unlock sources of air pollution during covid-19 lockdown in Chandigarh

Chandigarh: The impact of COVID-19 lockdown on ambient air quality of Chandigarh was studied by the Department of Environment Studies, Panjab University along with Department of Community Medicine & School of Public Health, Post Graduate Institute of Medical Education and Research, Chandigarh and Chandigarh Pollution Control Committee.

The study recently published in the journal Chemosphere entitled ‘Impact of COVID-19 lockdown on air quality in Chandigarh, India: Understanding the emission sources during controlled anthropogenic activities’ examined the trend of 14 air pollutants, including particulate matter (PM10, PM2.5), trace atmospheric gases (NO2, NO, NOx, SO2, Ozone, NH3, CO) and Volatile Organic Compounds (benzene, toluene, o-xylene, m,p-xylene, ethylbenzene) along with six meteorological parameters before and during the COVID-19 lockdown.

The study duration was divided into four parts, i.e., a) 21 days of before lockdown b) 21 days of the first phase of lockdown c) 19 days of the second phase of lockdown d) 14 days of the third phase of lockdown. The results showed a significant reduction in all the major pollutants during the first and second phases of lockdown. However, the concentrations of SO2, Ozone, and m,p-xylene kept on increasing throughout the study period, except for benzene, which continuously decreased.

Dr. Suman Mor, Chairperson, Department of Environment Studies, PU and the lead investigator of the study, highlighted that vehicular pollution contributes as a primary source of air pollution during different stages of lockdown. Further, she added that regional atmospheric transfer of pollutants from coal-burning and stubble burning were identified as secondary sources of air pollution.

Dr. Ravindra Khaiwal, Additional Professor of Environment Health, Department of Community Medicine and School of Public Health, PGIMER, who coordinated this study, mentioned that reduction in air pollution is linked to the decline in local emissions and frequent rainfall. He also highlighted that the increase in Ozone concentration seems to be associated with intense solar radiation and high temperature, which enhances the atmospheric reactivity during COVID-19 lockdown, leading to a rise in Ozone concentration not only in Chandigarh but many cities in India.

The percentage decrease in the concentrations during 1, 2 and 3 lockdown periods were 28.8 %, 23.4 % and 1.1 % for PM2.5 and 36.8 %, 22.8 % and 2.4 % for PM10, respectively. NO2 concentration was reduced by 23 %, 16.5 %, and 6.1 % in lockdown 1, 2, and 3, respectively, as compared to the average concentrations before the lockdown period.