Effects of COVID-19 lockdowns on fine particulate matter concentrations.

Hammer, Melanie S; van Donkelaar, Aaron; Martin, Randall V; McDuffie, Erin E; Lyapustin, Alexei; Sayer, Andrew M; Hsu, N Christina; Levy, Robert C et al. · Sci Adv · 2021

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Abstract

Lockdowns 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 (PM<sub>2.5</sub>) are of particular interest, as PM<sub>2.5</sub> is the leading environmental risk factor for mortality globally. We map global PM<sub>2.5</sub> concentrations for January to April 2020 with a focus on China, Europe, and North America using a combination of satellite data, simulation, and ground-based observations. We examine PM<sub>2.5</sub> concentrations during lockdown periods in 2020 compared to the same periods in 2018 to 2019. We find changes in population-weighted mean PM<sub>2.5</sub> concentrations during the lockdowns of -11 to -15 μg/m<sup>3</sup> across China, +1 to -2 μg/m<sup>3</sup> across Europe, and 0 to -2 μg/m<sup>3</sup> 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 PM<sub>2.5</sub> to emission sources.