Effects of the COVID-19 shutdown on spatial and temporal patterns of air pollution in New York City

Abstract

BACKGROUND AND AIM: To mitigate the COVID-19 pandemic, many governments across the world implemented “lockdown” measures. The resulting changes in economic activity had effects that cascaded across numerous aspects of everyday life. Using data from the New York City Community Air Survey (NYCCAS) and from the New York State (NYS) Department of Environmental Conservation (DEC), we characterized changes in fine particulate matter (PM2.5) and nitrogen dioxide (NO2) following the COVID-19 shutdown in New York City (NYC). METHODS: Difference-in-difference analysis of PM2.5 and NO2 measured at the DEC sites was used to calculate the change in citywide daily average pollutant concentrations that could be attributed to the COVID-19 shutdown. Spatial patterns of PM2.5 and NO2 in the winter and spring seasons of 2019 and 2020 were interpolated across NYC by fitting generalized additive models to measurements at 82-93 NYCCAS sites. Weather conditions and emission source trends were analyzed to determine the potential effects of meteorology and specific emission sources on the observed pollution changes. RESULTS:Difference-in-difference analysis suggests that PM2.5 and NO2 decreased by approximately 20% and 27%, respectively, because of the COVID-19 shutdown. Weather readings at LaGuardia Airport in NYC show little evidence that meteorology played a major role in observed pollutant decreases. Both PM2.5 and NO2 exhibited decreased spatial variability in NYC during the COVID-19 shutdown. Widespread increases in daytime (6am-8pm) traffic speeds and fewer open small businesses following the shutdown suggest that decreased vehicle traffic and business activity contributed to declines in air pollution during this period. CONCLUSIONS:Given the devastating effect the pandemic has had on lives and livelihoods, these pollution reductions are not truly cause for celebration. However, this study shows the potential for regulations on specific emission sources, such as traffic and commercial cooking, to control citywide pollution in the future. KEYWORDS: Air pollution, Oxides of nitrogen, Particulate matter, Policy, Causal inference