Air pollution and the pandemic: Long‐term PM_2.5 exposure and disease severity in COVID‐19 patients

Abstract

Background and objective: Ecological studies have suggested an association between exposure to particulate matter ≤2.5 μm (PM 2.5 ) and coronavirus disease 2019 (COVID-19) severity. However, these findings are yet to be validated in individuallevel studies. We aimed to determine the association of long-term PM 2.5 exposure with hospitalization among individual patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Methods: We estimated the 10-year (2009-2018) PM 2.5 exposure at the residential zip code of COVID-19 patients diagnosed at the University of Cincinnati healthcare system between 13 March 2020 and 30 September 2020. Logistic regression was used to determine the odds ratio (OR) and 95% CI for COVID-19 hospitalizations associated with PM 2.5 , adjusting for socioeconomic characteristics and comorbidities. Results: Among the 14,783 COVID-19 patients included in our study, 13.6% were hospitalized; the geometric mean (SD) PM 2.5 was 10.48 (1.12) μg/m 3 . In adjusted analysis, 1 μg/m 3 increase in 10-year annual average PM 2.5 was associated with 18% higher hospitalization (OR: 1.18, 95% CI: 1.11-1.26). Likewise, 1 μg/m 3 increase in PM 2.5 estimated for the year 2018 was associated with 14% higher hospitalization (OR: 1.14, 95% CI: 1.08-1.21). Conclusion: Long-term PM 2.5 exposure is associated with increased hospitalization in COVID-19. Therefore, more stringent COVID-19 prevention measures may be needed in areas with higher PM 2.5 exposure to reduce the disease morbidity and healthcare burden.

Initially High Correlation between Air Pollution and COVID-19 Mortality Declined to Zero as the Pandemic Progressed: There Is No Evidence for a Causal Link between Air Pollution and COVID-19 Vulnerability

“…When researchers estimate the effects of air pollution on all-cause mortality, they generally find that all-cause mortality increases more when exposure times are longer [ 14 ]. Some authors have found a similar result for the effect on COVID-19 mortality [ 15 ]. However, if the effect of long-term exposure is insignificant, the effect of short-term exposure is likely smaller and, thus, also insignificant.…”

Climate change and global health: A call to more research and more action

“…as well as natural substances (soil, dust, and bioaerosols). A recent study found that long‐term PM 2.5 exposure is associated with increased hospitalization for COVID‐19 24,25 and increases risk for acute asthma exacerbation. Air pollution and climate change significantly contribute to the onset and aggravation of allergic rhinitis and asthma as well as other chronic respiratory diseases 26,27 .…”

Long-term outdoor air pollution and COVID-19 mortality in London: an individual-level analysis

“…Research into air pollution and COVID-19 outcomes generally found that greater levels of pollution were associated with increased risk of severe disease and COVID-19 death. This has been shown in both ecological studies (e.g., [6, 7, 8, 9], reviewed by [10, 11], up to June 2021) and individual-level studies [12, 13, 14, 15, 16, 17, 18, 19, 20, 21]. Individual-level studies can adjust well for factors such as age, sex and socio-economic status [22, 6].…”

“…These studies again found positive associations [14,18,20,21,23,24], albeit of a smaller magnitude (≤11% increased risk), except one study, where fully adjusting for confounders removed the positive association [19]. However, some of these studies included low numbers of cases [12,14,16,19], some did not include a sample representative of the entire population [15,19] or suffered from participation bias [17,16,19], some only investigated one pollutant [20], and some did not adjust for all of the known risk factors which include age, sex, ethnicity, deprivation and health comorbidities [13,12,14,18,21]. All of these risk factors have been shown to confound the positive relationship between air pollution and COVID-19 mortality [25,6,26,27].…”

“…Individual-level studies can adjust well for factors such as age, sex and socio-economic status [22, 6]. Most individual-level studies investigated disease severity such as hospitalisation [13, 12, 15, 17, 14, 16, 21, 19], generally identifying increased risk levels of ≥13%, in particular for PM 2.5 (particulate matter with a small aerodynamic diameter (≤2.5μm)), although two studies found a lower or no increased risk [21, 19]. To date, few individual-level studies have analysed the effect of long-term air pollution on mortality following COVID-19 disease.…”