Effects of COVID-19 lockdowns on fine particulate matter concentrations

Interventions during the COVID-19 pandemic provide an unprecedented opportunity to examine the effects of human activity on air quality. The effects on fine particulate matter (PM2.5) are of interest, as PM2.5 is the leading environmental determinant of health. We map global PM2.5 concentrations with a focus on China, Europe, and North America using a combination of satellite data, simulation, and ground observations for January-April 2020. We examine PM2.5 concentrations during the lockdown periods in 2020 compared to the same periods in 2018-2019. We find changes in population-weighted mean PM2.5 concentrations during the lockdowns of -11 to -17 µg/m3 across China, -2 to +1 µg/m3 across Europe, and 0 to -2 µg/m3 across North America. We explain these changes through a combination of meteorology and emission reductions, mostly due to transportation. This work demonstrates regional differences in the sensitivity of PM2.5 to emission sources.