COVID-19 pandemic reveals persistent disparities in nitrogen dioxide pollution

Significance

We leverage the unparalleled changes in human activity during COVID-19 and the unmatched capabilities of the TROPOspheric Monitoring Instrument to understand how lockdowns impact ambient nitrogen dioxide ( ${\mathrm{N}\mathrm{O}}_2$ ) pollution disparities in the United States. The least White communities experienced the largest ${\mathrm{N}\mathrm{O}}_2$ reductions during lockdowns; however, disparities between the least and most White communities are so large that the least White communities still faced higher ${\mathrm{N}\mathrm{O}}_2$ levels during lockdowns than the most White communities experienced prior to lockdowns, despite a $\sim$ 50% reduction in passenger vehicle traffic. Similar findings hold for ethnic, income, and educational attainment population subgroups. Future strategies to reduce ${\mathrm{N}\mathrm{O}}_2$ disparities will need to target emissions from heavy-duty vehicles.

Abstract

The unequal spatial distribution of ambient nitrogen dioxide ( ${\mathrm{N}\mathrm{O}}_2$ ), an air pollutant related to traffic, leads to higher exposure for minority and low socioeconomic status communities. We exploit the unprecedented drop in urban activity during the COVID-19 pandemic and use high-resolution, remotely sensed ${\mathrm{N}\mathrm{O}}_2$ observations to investigate disparities in ${\mathrm{N}\mathrm{O}}_2$ levels across different demographic subgroups in the United States. We show that, prior to the pandemic, satellite-observed ${\mathrm{N}\mathrm{O}}_2$ levels in the least White census tracts of the United States were nearly triple the ${\mathrm{N}\mathrm{O}}_2$ levels in the most White tracts. During the pandemic, the largest lockdown-related ${\mathrm{N}\mathrm{O}}_2$ reductions occurred in urban neighborhoods that have 2.0 times more non-White residents and 2.1 times more Hispanic residents than neighborhoods with the smallest reductions. ${\mathrm{N}\mathrm{O}}_2$ reductions were likely driven by the greater density of highways and interstates in these racially and ethnically diverse areas. Although the largest reductions occurred in marginalized areas, the effect of lockdowns on racial, ethnic, and socioeconomic ${\mathrm{N}\mathrm{O}}_2$ disparities was mixed and, for many cities, nonsignificant. For example, the least White tracts still experienced $\sim$ 1.5 times higher ${\mathrm{N}\mathrm{O}}_2$ levels during the lockdowns than the most White tracts experienced prior to the pandemic. Future policies aimed at eliminating pollution disparities will need to look beyond reducing emissions from only passenger traffic and also consider other collocated sources of emissions such as heavy-duty vehicles.