Spatio-temporal assessment of ambient air quality, their health effects and improvement during COVID-19 lockdown in one of the most polluted cities of India.

The present work aims to investigate seasonal variations in air pollution levels in Lucknow and assess the ambient air quality of the city together with highlighting the health impacts of major pollutants like PM, PM, SO, NO, Pb, Ni and aerosols from 2010 to 2019. The maximum and minimum values of PM, PM, SO, NO, Pb and Ni were found to be 270.75 and 122.45 μg/m, 124.95 and 95.52 μg/m, 25.60 and 8.05 μg/m, 75.65 and 23.85 μg/m, 0.66 and 0.03 μg/m and 0.07 and 0.01 ng/m, respectively. Health impact of particulate matter has also been assessed with AirQ+, and it was estimated that long-term exposure of PM was attributed to between 37 and 48% for post-neonatal (age 1-12 months) mortality rate due to all causes, whereas long-term attributable proportions in mortality due to exposure of PM were to about 19 to 28% from all causes. Further, an attempt has also been made to evaluate the impact of lockdown amid COVID-19 on the ambient air quality of Lucknow. During the lockdown, PM levels reduced by 65% (at Gomti Nagar), 23% (at central school), 79% (at Lalbagh) and 35% (at Talkatora), due to which, air quality index of Gomti Nagar came down to 43, well below 50 which falls in the healthy range. NO levels also came down. However, levels of SO did not show significant reduction. Correlating the data between aerosol optical depth and Angstrom exponent by Pearson correlation analysis revealed a significant positive correlation (r = 0.65, P < 0.001).