Air pollution exposure may affect COVID-19 severity, mortality

Exposure to ambient air pollution and nitrogen dioxide may influence COVID-19 severity and related mortality, researchers reported in the American Journal of Respiratory and Critical Care Medicine.

“Long-term and short-term air pollution exposure increases the risk of severe COVID-19, including hospitalizations and deaths from SARS-CoV-2 infection. Improving air quality and reducing personal air pollution exposure could be beneficial for preventing severe COVID-19 outcomes,” Zhanghua Chen, PhD, assistant professor of population and public health sciences in the department of preventive medicine at the Keck School of Medicine of USC, told Healio.

Chen and colleagues conducted a large, multiethnic, population-based cohort study that included 74,915 individuals (mean age, 42.5 years; 54% women; 66% Hispanic) who were diagnosed with COVID-19 at Kaiser Permanente Southern California from March to August 2020. Using patients’ residential address history, researchers estimated 1-year and 1-month averaged exposure to ambient air pollutants, including fine particulate matter (PM_2.5), nitrogen dioxide (NO₂) and ozone, prior to COVID-19 diagnosis.

“It is hypothesized that air pollution may increase the risk of severe COVID-19 through the direct effect on lung inflammation and altered immune response to virus infection, and through the adverse effect on other comorbidities related to severe COVID-19, such as obesity, diabetes and cardiovascular diseases,” Chen told Healio. “Although ecological analyses have shown some relationship of long-term air pollution exposure, including fine particle and nitrogen dioxide, with COVID-19 mortality by averaging data from large geographic areas and heterogenous populations, there is a critical need of evidence suggested by cohort studies linking individual-level air pollution exposure and the risk of severe COVID-19 outcomes adjusting for variations on individual confounders such as socio-characteristics and disease history.”

Overall, the rate of hospitalization was 6.3%, intensive respiratory support 2.4%, ICU admission 1.5% and mortality 1.5%.

Average 1-year PM_2.5 and 1-month NO₂ exposures were associated with severity of COVID-19 infection after adjusting for socio-characteristics and comorbidities, according to the researchers. For each 1 standard deviation increase in 1-year PM_2.5, the association remained for hospitalization (OR = 1.24; 95% CI, 1.16-1.32), intensive respiratory support (OR = 1.33; 95% CI, 1.2-1.47) and ICU admission (OR = 1.32; 95% CI, 1.16-1.51). For 1-month NO₂, the association also remained for hospitalization (OR = 1.12; 95% CI, 1.06-1.17), intensive respiratory support (OR = 1.18; 95% CI, 1.1-1.27) and ICU admission (OR = 1.21; 95% CI, 1.11-1.33), according to the results.

Regarding mortality, researchers reported associations between mortality and 1-year PM_2.5 (HR = 1.14; 95% CI, 1.02-1.27) and 1-month NO₂ (HR = 1.07; 95% CI, 0.98-1.16).

Looking forward, “beyond testing personal interventional tools, several main concerns now about COVID-19 are the new variants and long COVID,” Chen told Healio. “It will be important for future research to investigate whether air pollution exposure also increases COVID-19 incidence and severity for new virus variants, and whether air pollution could also have detrimental impact on long COVID.”

Reference:

• Exposure to air pollution can worsen patient outcomes from COVID-19. Published May 25, 2022. Accessed May 26, 2022.