COVID-19 disease severity in hospitalized patients is associated with short- and long-term exposure to air pollutants

Abstract

Background and Aim Existing evidence suggests that exposure to air pollutants (AP) such as particulate matter (PM2.5 and PM10), nitrogen dioxide (NO2) and black carbon (BC) is associated with COVID-19 infection rates and mortality. We investigated whether exposure to AP was associated with COVID-19 disease severity in a cohort of hospitalised COVID-19 patients. Methods 329 COVID-19 patients were recruited at the time of admission to hospital. Clinical parameters and outcomes were collected from medical records, including the duration of stay, the early-warning score (EWS), oxygen saturation, and PaO2/FiO2 ratios. Daily exposure levels for PM2.5, PM10, NO2 and BC were modelled using a high-resolution spatiotemporal model. Black carbon particles in blood were quantified using femtosecond pulsed laser illumination. Associations between exposure to air pollutants and clinical outcomes were modelled using multiple regression models while adjusting for potential confounders. Results The duration of stay increased by 1 to 6 days for an interquartile range (IQR) increase in average exposure to AP in the week before admission (PM2.5: +5.2 days, NO2: +5.8 days). Similarly, an IQR increase in long-term exposure (to AP was associated with increased duration of stay (PM2.5: +2.8 days, NO2: +3.2 days, BC: +2.8 days). Furthermore, an increase in PM2.5 exposure 1 week before admission was associated with higher EWS (+0.40). Finally, IQR increases in long-term exposure to PM10, BC and NO2 as well as blood black carbon load were associated with odds of admission to the intensive care unit (OR: +1.32, +2.12, +2.46 and +1.19 respectively). Conclusion Exposure to AP was associated with duration of stay and EWS scores at the time of admission, which implies a potential link between AP exposure and COVID-19 disease severity, and a significant influence of AP exposure on the pressure on medical care systems during the COVID-19 pandemic.