Effects of Short-Term Air Pollution Exposure on U.S. COVID-19 Mortality (WP-22-02)
Ruohao Zhang, Jeffrey Whittle, Vladimir Atanasov, John Meurer, Paula Natalia Barreto Parra, and Bernard Black
Importance: Prior studies have shown that long-term exposure to air pollution predicts higher COVID-19 mortality, but there is limited evidence on the effect of short-term fluctuations in air pollution levels.
Objective: To determine whether short-term changes in county air-pollution levels predict COVID-19 mortality in the U.S.
Design: We use county-level data regarding COVID-19 deaths, air pollution, temperature, precipitation, and lagged SARS-CoV2 infection and vaccination rates, with county and date fixed effects, to assess whether, and for how long, variation in local air pollution predicts COVID-19 mortality rates.
Setting: We use county-by-day data on COVID-19 deaths, infections, and vaccination rates, the aerosol optical depth (AOD) measure of daily air pollution from NASA MODIS satellite data, and Oregon State University PRISM database on daily precipitation and temperature, over March 2020 through August 2021.
Participants: 2,942 U.S. Counties with data on COVID-19 mortality and air pollution levels, after interpolation for days with missing pollution data.
Exposures: Daily air pollution levels; lagged daily COVID-19 infection and vaccination rates.
Main Outcomes and Measurements: County-level COVID-19 deaths measured as the natural log of (7-day moving average daily deaths +1).
Results: Higher AOD levels predict modestly higher COVID-19 mortality for the next 2-3 weeks, controlling for local lagged infections, lagged vaccination rates, temperature, and precipitation. A one-standard-deviation increase in AOD over the previous 14 days predicts 5.9% higher COVID-19 mortality.
Conclusion and Relevance: The evidence in this study on the association between higher near-term air pollution and COVID-19 mortality suggests that persons who are infected with or at risk for SARS-CoV-2 infection should limit their exposure to air pollution. Paying greater attention to indoor ventilation and air filtering, including in hospitals, may reduce COVID-19 deaths.