Impact of COVID-19 pandemic lockdown on atmospheric concentrations of particulate matter, trace gases and volatile organic compounds at a suburban site of Agra

The present manuscript aims to study the impact of the lockdown imposed during the COVID-19 pandemic on the air quality of Agra, India. Particulate matter (PM2.5), trace gases, and volatile organic compounds (VOCs) were evaluated to detect changes in air quality during pre-lockdown, lockdown, and post-lockdown periods. The average concentration of PM(2.5 )in pre-lockdown was 130 +/- 79.3 mu g/m(3), which reduced to 48.3 +/- 24.9 mu g/m(3 )(62.8%) during the lockdown period, while during post-lockdown it again increased to 59.3 +/- 26.6 mu g/m(3). Average concentrations of NO, NO2 and NOx, in pre-lockdown were 5.1 +/- 0.5, 2.3 +/- 0.3 and 6.2 +/- 2.9 ppb, respectively, which decreased by 60.8, 56.5, and 67.7%, respectively, during lockdown as compared to pre-lockdown period. Average concentration of carbon monoxide (CO) was 710.7 +/- 315.7 ppb in pre-lockdown, decreased to 381.8 +/- 164.4 ppb (46.3%) during the lockdown and increased to 401.3 +/- 280.5 ppb (5.2%) as post-lockdown occurred. Similar trend was observed for benzene and toluene. Average concentration of tropospheric ozone (O-3) before the lockdown was 24.5 +/- 9.5 ppb which rose to 40.4 +/- 12.9 ppb (64.9%) during lockdown and reduced to 29.2 +/- 5.8 ppb during post-lockdown period. CO may have reduced due to decreased vehicular intensity, while O-3 showed high concentration due to the weakened chemical titration of O-3 with NO. Interspecies ratio for benzene/toluene was 0.7, which suggests dominance of vehicular emissions and fresh air masses. The study may be beneficial in providing information for air pollution reduction and planning for future post-pandemic air quality management.

Automated summary

The present study aims to investigate the effect of the COVID-19 lockdown on the air quality in Agra, India. Results showed significant reductions in PM2.5, nitrogen oxide, carbon monoxide, and ozone concentrations during the lockdown period, with a subsequent increase after the lockdown was lifted. The findings have important implications for air pollution reduction and future post-pandemic air quality management.