Ambient Air Pollution and Risk of ARDS and Mortality in Moderate to Severe COVID-19

Ambient air pollution is known to exacerbate respiratory illnesses. However, its impact on COVID-19 outcomes remains underexplored. We investigated the association between ambient air pollution and outcomes in patients with moderate to severe COVID-19.

We analysed 1867 hospitalized patients from a multicentre Korean cohort. Individual-level exposure to five air pollutants (SO₂, CO, NO₂, PM₁₀ and PM_2.5) was assessed over short-term (3-day) and long-term (3-year) periods. The risks of acute respiratory distress syndrome (ARDS) and 30-day mortality were evaluated using models adjusted for clinical and meteorological factors. Pollutant exposure was analysed both as quartiles and continuous variables to estimate effects per unit increase.

Short-term CO exposure was associated with increased ARDS incidence (per 0.1 ppm increase OR 1.18) and 30-day mortality (HR 1.15). Long-term NO₂ exposure was associated with higher ARDS risk (per 1 ppb OR 1.11). Long-term PM₁₀ exposure was also associated with ARDS incidence (per 10 μg/m³ OR 2.24). For mortality, short-term NO₂ (per 1 ppb HR 1.02) and PM_2.5 (per 10 μg/m³ HR 1.14) exposure were additionally associated with increased risk. These associations were consistent in quartile-based analyses.

Both short- and long-term exposure to ambient air pollution were associated with worse COVID-19 outcomes, including ARDS and mortality. CO, often overlooked in pollution surveillance, showed the most consistent impact. These findings highlight the importance of air quality in pandemic preparedness and public health policy.