Long-term exposure to fine particulate matter and hospitalization in COVID-19 patients

Background: Ecological evidence suggests that exposure to air pollution affects coronavirus disease 2019 (COVID-19) outcomes. However, no individual-level study has confirmed the association to date. Methods: We identified COVID-19 patients diagnosed at the University of Cincinnati hospitals and clinics and estimated particulate matter <= 2.5 mu m (PM2.5) exposure over a 10-year period (2008-2017) at their residential zip codes. We used logistic regression to evaluate the association between PM2.5 exposure and hospitalizations for COVID-19, adjusting for socioeconomic characteristics and comorbidities. Results: Among the 1128 patients included in our study, the mean (standard deviation) PM2.5 was 11.34 (0.70) mu g/m(3) for the 10-year average exposure and 13.83 (1.03) mu g/m(3) for the 10-year maximal exposures. The association between long-term PM2.5 exposure and hospitalization for COVID-19 was contingent upon having preexisting asthma or chronic obstructive pulmonary (COPD) (P-interaction = 0.030 for average PM2.5 and P-interaction = 0.001 for maximal PM2.5). In COVID-19 patients with asthma or COPD, the odds of hospitalization were 62% higher with 1 mu g/m(3) increment in 10-year average PM2.5 (odds ratio [OR]: 1.62, 95% confidence interval [CI]: 1.00-2.64) and 65% higher with 1 mu g/m(3) increase in 10-year maximal PM2.5 levels (OR: 1.65, 95% CI: 1.16-2.35). However, among COVID-19 patients without asthma or COPD, PM2.5 exposure was not associated with higher hospitalizations (OR: 0.84, 95% CI: 0.65-1.09 for average PM2.5 and OR: 0.78, 95% CI: 0.65-0.95 for maximal PM2.5). Conclusions: Long-term exposure to PM2.5 is associated with higher odds of hospitalization in COVID-19 patients with pre-existing asthma or COPD.