Short-term exposure to air pollution does not alter the outcome of ARDS in Europe

Long-term exposure to air pollutants worsens acute respiratory distress syndrome (ARDS) frequency, but the impact of short-term exposure remains understudied. With coronavirus disease 2019 (COVID-19) causing a surge in ARDS cases and lockdown-related air pollution changes, we explored how brief air pollutant exposure affects ventilator-free days by day 28 (VFD28) in COVID-19 ARDS patients in French metropolitan intensive care units (ICUs).

Using a high-resolution AZUR method, exposure to nitrogen dioxide (NO₂), fine particles under 2.5 or 10 µm/m³ in aerodynamic diameter (PM_2.5 and PM₁₀), and ozone (O₃) in the week before admission was determined for each patient. COVID-19 ARDS patients from seven ICUs between March 2020 and March 2022 were categorized into high or low exposure groups based on whether their exposure exceeded or fell below the population's median levels.

Of 747 patients, 184 (25%) had died, and 170 (23%) remained on mechanical ventilation on day 28. The median VFD28 was 1 [0-20]. The standardized hazard ratio [IC 95%] for successful extubation by day 28 in the high short-term exposure group, compared to the low-exposure group, was 1.08 [0.91-1.3] for PM_2.5, 1.08 [0.78-1.51] for PM₁₀, 1.01 [0.84-1.2] for NO₂, and 1.08 [0.91-1.29] for O₃. After adjusting for potential confounding factors, no significant difference was observed in VFD28 or day-28 mortality between the low and high-exposure groups.

We found no association between short-term exposure to air pollutants and VFD28 or day 28 mortality in a population of COVID-19 related ARDS patients.