Comparative Health Risk Assessment of Black Carbon and Particulate Matter Emissions in East India During the COVID-19 First and Second Waves

“Impact of COVID-19 Lockdowns on Air Quality in East India: A Comparative Analysis of PM2.5 and Black Carbon Emissions during the First and Second Waves of the Pandemic” The COVID-19 pandemic has had a devastating toll on human lives worldwide, leading many countries to implement strict lockdowns and restrictions in an effort to combat the virus. While these measures were crucial for public health, they also had significant implications for the global economy and human well-being. One notable effect of the lockdowns was the reduction in emissions of particulate matter (PM2.5), Black Carbon (BC), aerosols, and other air pollutants in the atmosphere. This decline in human activities during the lockdowns contributed to an improvement in air quality. The pandemic unfolded in two waves: the First Wave (March–June 2020) and the Second Wave (March–June 2021). During both of these periods, we closely monitored the levels of PM2.5, BC, and meteorological parameters in the industrial cities of Sakchi (S1) and Gamharia (S2) in East India. In the First Wave, there was a noticeable drop in PM2.5 mass concentrations at S1 and S2, with levels ranging from 134 to 27 μg m⁻³ and 127 to 34 μg m⁻³, respectively. Similarly, BC mass concentrations showed a decrease, ranging from 56 to 10 μg m⁻³ at S1 and 48.8 to 10 μg m⁻³ at S2. In the Second Wave of COVID-19, we observed a rise in PM2.5 mass concentrations, with levels ranging from 117 to 164 μg m⁻³ at S1 and 123 to 159 μg m⁻³ at S2. The corresponding BC mass concentrations ranged from 23.5 to 66.6 μg m⁻³ at S1 and 23.2 to 71 μg m⁻³ at S2. This comparison indicates that PM2.5 and BC mass concentrations increased from the first to the Second Wave of the pandemic. However, it is worth noting that due to partial lockdowns or shutdowns during the Second Wave, the mass concentrations might still have been lower compared to regular days. Furthermore, the analysis of backward trajectories revealed that aerosol movement experienced a more significant reduction during the First Wave compared to the Second Wave, which had a moderate effect. In terms of health risks associated with BC exposure, the Npsc values ranged from 20.8 to 103.7 for CM, LC, LBW, and PLED during the First Wave and 14.4 to 61.6 during the Second Wave. In conclusion, the COVID-19 lockdowns had a discernible impact on air quality in East India, with reduced emissions of PM2.5 and BC during the First Wave and a partial improvement during the Second Wave. However, it is crucial to consider the complex interactions between human activities, air pollution, and public health when interpreting these findings.