COVID-19 pandemic reveals persistent disparities in nitrogen dioxide pollution

Abstract

The unequal spatial distribution of ambient nitrogen dioxide (NO2), 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 NO2 observations to investigate disparities in NO2 levels across different demographic subgroups in the United States. We show that, prior to the pandemic, satellite-observed NO2 levels in the least White census tracts of the United States were nearly triple the NO2 levels in the most White tracts. During the pandemic, the largest lockdown-related NO2 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. NO2 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 NO2 disparities was mixed and, for many cities, nonsignificant. For example, the least White tracts still experienced ∼1.5 times higher NO2 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.

Space‐Based Observational Constraints on NO2 Air Pollution Inequality From Diesel Traffic in Major US Cities

“…Absolute NO 2 disparities (molecules cm −2 ) are strongly associated with local city-level NO 2 pollution (Figure 1h), with a Pearson correlation coefficient (r) of 0.82 for the combined race-ethnicity and income metric (LIN-HIW). At the same time, relative inequalities (%) are only moderately associated with city-level NO 2 (r = 0.46), suggesting that sustained NO x emission control will reduce but not eliminate NO 2 disparities, a result consistent with work investigating trends in NO 2 inequality between 2000 and 2010 using land-use regression NO 2 data sets (Clark et al, 2017) and before and during COVID-19-related activity changes using TROPOMI NO 2 TVCDs (Kerr et al, 2021).…”

“…While HDDVs are the largest source of UA-level disparities, stationary sources may be more important across more suburban metropolitan areas. Regulatory controls on gasoline-powered vehicles and electricity generation between 2000 and 2010 decreased absolute, although not relative, NO 2 inequalities from these sources across the United States (Clark et al, 2017), and an analysis exploiting COVID-19-related reductions in passenger vehicle traffic suggest HDDV emissions dominate relative NO 2 inequalities in recent years (Kerr et al, 2021). Based on the FIVE18-19, summertime HDDV NO x emission densities decrease by 62 ± 2% on weekends, with diesel traffic still causing 26 ± 6% of LIN-HIW NO x emissions inequalities on weekends.…”

“…Nitrogen dioxide (NO 2 ) is a combustion product and a key control over atmospheric oxidation and secondary pollutant formation. Communities of color and those with lower household incomes often experience elevated NO 2 concentrations and exposures (Clark et al, 2014(Clark et al, , 2017Kerr et al, 2021;Kravitz-Wirtz et al, 2016;Rosofsky et al, 2018;Southerland et al, 2021). Epidemiological studies indicate an association between NO 2 exposure and/or its co-emissions and various adverse health effects (Brook et al, 2007;Brunekreef & Holgate, 2002;Burnett et al, 2004).…”

Climate Solutions Double as Health Interventions

“…Similarly, electrifying 27% of China's private vehicle fleet by 2030 could prevent 17,500 premature deaths annually from improvements in air quality [30]. Several studies have demonstrated that air pollution from vehicle traffic emissions disproportionately affects people of color and low-income populations, indicating that climate solutions aimed at reducing vehicles emissions could also improve health and equity [31,32].…”

Diesel passenger vehicle shares influenced COVID-19 changes in urban nitrogen dioxide pollution

“…Reductions in urban NO 2 during the pandemic (hereafter '∆NO 2 ') varied greatly across the world (e.g. [6][7][8][9]). Direct comparisons of ∆NO 2 among cities are inherently complicated by different meteorological patterns [10], stay-at-home measures, and levels of adherence to these measures in each city.…”