Independent associations of short- and long-term air pollution exposure with COVID-19 mortality among Californians

Brittney Marian; Ying Yan; Zhanghua Chen; Fred Lurmann; Kenan Li; Frank Gilliland; Sandrah P Eckel; Erika Garcia

doi:10.1016/j.envadv.2022.100280

Independent associations of short- and long-term air pollution exposure with COVID-19 mortality among Californians

Environ Adv. 2022 Oct:9:100280. doi: 10.1016/j.envadv.2022.100280. Epub 2022 Aug 9.

Authors

Brittney Marian¹, Ying Yan¹, Zhanghua Chen¹, Fred Lurmann², Kenan Li³, Frank Gilliland¹, Sandrah P Eckel¹, Erika Garcia¹

Affiliations

¹ Department of Population and Public Health Sciences, University of Southern California, Los Angeles, CA, United States of America.
² Sonoma Technology, Inc, Petaluma, CA, United States of America.
³ Spatial Sciences Institute, University of Southern California, Los Angeles, CA, United States of America.

Abstract

The growing literature demonstrating air pollution associations on COVID-19 mortality contains studies predominantly examining long-term exposure, with few on short-term exposure, and rarely both together to estimate independent associations. Because mechanisms by which air pollution may impact COVID-19 mortality risk function over timescales ranging from years to days, and given correlation among exposure time windows, consideration of both short- and long-term exposure is of importance. We assessed the independent associations between COVID-19 mortality rates with short- and long-term air pollution exposure by modeling both concurrently. Using California death certificate data COVID-19-related deaths were identified, and decedent residential information used to assess short- (4-week mean) and long-term (6-year mean) exposure to particulate matter <2.5µm (PM_2.5), nitrogen dioxide (NO₂), and ozone (O₃). Negative binomial mixed models were fitted on weekly census tract COVID-19 mortality adjusting for potential confounders with random effects for county and census tract and an offset for population. Data were evaluated separately for two time periods March 16, 2020-October 18, 2020 and October 19, 2020-April 25, 2021, representing the Spring/Summer surges and Winter surge. Independent positive associations with COVID-19 mortality were observed for short- and long-term PM_2.5 in both study periods, with strongest associations observed in the first study period: COVID-19 mortality rate ratio for a 2-μg/m³ increase in long-term PM_2.5 was 1.13 (95%CI:1.09,1.17) and for a 4.7-μg/m³ increase in short-term PM_2.5 was 1.05 (95%CI:1.02,1.08). Statistically significant positive associations were seen for both short- and long-term NO₂ in study period 1, but short-term NO₂ was not statistically significant in study period 2. Results for long-term O₃ indicate positive associations, however, only marginal significance is achieved in study period 1. These findings support an adverse effect of long-term PM_2.5 and NO₂ exposure on COVID-19 mortality risk, independent of short-term exposure, and a possible independent effect of short-term PM_2.5.

Keywords: Air pollution; COVID; COVID-19, coronavirus disease 2019; Mortality; NO2, nitrogen dioxide; Nitrogen dioxide; Ozone; PM10, particulate matter < 10 µm; PM2.5, particulate matter < 2.5 µm; Particulate matter; SD, standard deviation.