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[Preprint]. 2020 May 7:2020.05.04.20090746.
doi: 10.1101/2020.05.04.20090746.

Urban Air Pollution May Enhance COVID-19 Case-Fatality and Mortality Rates in the United States

Donghai Liang  1 , Liuhua Shi  1 , Jingxuan Zhao  2 , Pengfei Liu  3 , Joel Schwartz  4 , Song Gao  5 , Jeremy Sarnat  1 , Yang Liu  1 , Stefanie Ebelt  1 , Noah Scovronick  1 , Howard H Chang  6
Affiliations

Urban Air Pollution May Enhance COVID-19 Case-Fatality and Mortality Rates in the United States

Donghai Liang et al. medRxiv. .

Update in

Abstract

Background: The novel human coronavirus disease 2019 (COVID-19) pandemic has claimed more than 240,000 lives worldwide, causing tremendous public health, social, and economic damages. While the risk factors of COVID-19 are still under investigation, environmental factors, such as urban air pollution, may play an important role in increasing population susceptibility to COVID-19 pathogenesis.

Methods: We conducted a cross-sectional nationwide study using zero-inflated negative binomial models to estimate the association between long-term (2010-2016) county-level exposures to NO2, PM2.5 and O3 and county-level COVID-19 case-fatality and mortality rates in the US. We used both single and multipollutant models and controlled for spatial trends and a comprehensive set of potential confounders, including state-level test positive rate, county-level healthcare capacity, phase-of-epidemic, population mobility, sociodemographic, socioeconomic status, behavior risk factors, and meteorological factors.

Results: 1,027,799 COVID-19 cases and 58,489 deaths were reported in 3,122 US counties from January 22, 2020 to April 29, 2020, with an overall observed case-fatality rate of 5.8%. Spatial variations were observed for both COVID-19 death outcomes and long-term ambient air pollutant levels. County-level average NO2 concentrations were positively associated with both COVID-19 case-fatality rate and mortality rate in single-, bi-, and tri-pollutant models (p-values<0.05). Per inter-quartile range (IQR) increase in NO2 (4.6 ppb), COVID-19 case-fatality rate and mortality rate were associated with an increase of 7.1% (95% CI 1.2% to 13.4%) and 11.2% (95% CI 3.4% to 19.5%), respectively. We did not observe significant associations between long-term exposures to PM2.5 or O3 and COVID-19 death outcomes (p-values>0.05), although per IQR increase in PM2.5 (3.4 ug/m3) was marginally associated with 10.8% (95% CI: -1.1% to 24.1%) increase in COVID-19 mortality rate.

Discussions and conclusions: Long-term exposure to NO2, which largely arises from urban combustion sources such as traffic, may enhance susceptibility to severe COVID-19 outcomes, independent of long-term PM2.5 and O3 exposure. The results support targeted public health actions to protect residents from COVID-19 in heavily polluted regions with historically high NO2 levels. Moreover, continuation of current efforts to lower traffic emissions and ambient air pollution levels may be an important component of reducing population-level risk of COVID-19 deaths.

Keywords: Air pollution; COVID-19; Case-fatality rate; Mortality; Nitrogen dioxide.

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Conflict of interest statement

Potential Conflicts of Interest: The authors have no conflicts of interest relevant to this article to disclose

Figures

Figure 1
Figure 1
County-level COVID-19 Case-fatality Rate (A) and Mortality Rate per 1 Million people (B) as of April 29, 2020.
Figure 2
Figure 2
County-level Annual Average Concentrations of Nitrogen Dioxide (NO2, A), Fine Particulate Matter (PM2.5, B), and Ozone (C) for the period 2010–2016.
Figure 3
Figure 3. Percent Change in County-level COVID-19 Case-fatality Rate (A) and Mortality Rate (B) Per Inter Quartile Range (IQR) increase in Long-Term Air Pollutant Concentrations.
Effect estimates and 95% confidence interval were calculated using county-level concentrations of nitrogen dioxide (NO2, red), ozone (green), and fine particulate matter (PM2.5, blue) averaged between 2010–2016, controlling for covariates including county-level number of case per 1000 people, social deprivation index, population density, percent of residents over 60 years old, percent of male, body mass index, smoking rate, number of regular hospital beds per 1000 people, number of intensive units beds per 1000 people, number of medical doctors per 1000 people, average mobility index assessed in March and April 2020, average temperature and humidity between January 22 to April 29, 2020, state-level COVID-19 test positive rate as of April 29, 2020, and spatial smoother with a degree freedom of 5 for both latitude and longitude. IQRs of NO2, PM2.5, and O3 averaged between 2010–2016 were 4.6 parts per billion (ppb), 3.4 ug/m3, and 2.8 ppb, respectively.
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