Disparities in PM2.5 exposure and population density influence SARS-CoV-2 transmission among racial and ethnic minorities

Abstract

There is overwhelming evidence that minority populations across the United States (US) have been disproportionately affected by the coronavirus (COVID-19) pandemic. While the disparities are clear, the reasons underlying the rapidity of disease spread—characterized by the basic reproduction ratio R _0 —in these communities are less so. Here, we investigate the relative impact of disparities in socioeconomic, environmental, and lung health factors on R _0 across 12 major metropolitan statistical areas (MSAs) in the US at the county-level. We inferred county-level R _0 values using an established metapopulation epidemiological model corresponding to the period 1 March–30 April 2020 marked by a rapid surge in COVID-19 cases across the US and implementation of strict lockdown measures. We find that disparities in long-term, ambient PM _2.5 exposure (particulate matter with aerodynamic diameter 2.5 μ m or less) and population density have an outsized effect on R _0 in comparison to disparities in the other factors. We also find that the effect of increasing population density on R _0 is dependent on ambient PM _2.5 mass concentrations. PM _2.5 exposure has a well-established causal effect with increased risks and severe outcomes during previous infectious disease outbreaks. Overall, we find the largest disparities in PM _2.5 exposure, population density, and associated increase in R _0 among the Hispanic-American population, followed by Asian-American and African-American populations, respectively. Longstanding geographic segregation of minority communities has led to extremely large fluctuations in county-level racial and ethnic minority fractions. As such, we conclude by providing each MSA with a roadmap for identifying which communities should be targeted for PM _2.5 mitigation policy implementation. The methodology and results of this study may be extrapolatable to the rest of the world toward discerning the consequences of population density and PM _2.5 disparities in COVID-19 spread.

Keywords

• COVID-19
• air pollution
• PM2.5
• reproduction ratio
• racial disparities