B96-02 Cumulative Air Pollution Exposure Increases the Severity of Acute Respiratory Failure: A U.S. Multicenter Study

Abstract Rationale Acute respiratory failure (ARF) causes 2 million intensive care unit (ICU) admissions annually in the United States with increasing mortality rates over the last decade. Ambient air pollution is a leading global cause of morbidity and mortality, yet its impact on critically ill patients remains poorly understood. The purpose of our study was to investigate whether higher cumulative exposure to fine particulate matter (PM2.5) and nitrogen dioxide (NO2) are associated with increased severity of community-acquired ARF. Methods We conducted a retrospective multicenter cohort study across seven U.S. academic medical centers participating in the Common Longitudinal ICU Format (CLIF) consortium from 2018–2024. Adults admitted to the ICU meeting clinical ARF criteria were geocoded by residential county and linked to annual mean satellite-derived PM2.5 (µg/m³) and NO2 (ppb) cumulative exposures prior to admission, along with census tract-level sociodemographics. These covariates were included in Fine–Gray competing risks regression models to estimate subdistribution hazard ratios (SHRs) for extubation, discharge on ventilation, and death. Site-specific SHRs were pooled using a random-effects meta-analysis with restricted maximum likelihood estimation to account for between-site heterogeneity. Results The cohort included 128,808 ICU patients with ARF (mean age 62 ± 15 years, 59% male, 32% non-Hispanic Black) with an in-hospital mortality rate of 16.9 ± 1.6% and a mean mechanical ventilation duration of 53.4 ± 156.5 hours. Mean annual PM2.5 and NO2 exposures were 7.6 ± 1.5 µg/m³ and 6.0 ± 2.9 ppb, respectively, with regional variability. Each 10 ppb increase in cumulative NO2 exposure was associated with a 5% higher risk of in-hospital death (95% CI 1.03–1.08) and a 2% longer duration of invasive ventilation (95% CI 1.00–1.04). Each 10 µg/m³ increase in cumulative PM2.5 exposure was associated with a 9% higher risk of in-hospital death (95% CI 1.03–1.16) and a 9% higher risk of 30-day death (1.09, 95% CI 1.02–1.17). In competing-risk analyses, greater cumulative NO2 exposure was associated with a 51% higher SHR of death (95% CI 1.07–2.13), while greater PM2.5 exposure was linked to a 2.45-fold higher SHR of death (95% CI 1.03–5.79), relative to recovery. Conclusions Cumulative exposure to ambient air pollution was consistently linked to increased time on invasive ventilation and mortality among critically ill patients with ARF. These findings suggest that PM2.5 and NO2 may impede recovery even within controlled ICU settings, which should be considered in clinical decision making. This abstract is funded by: 5T32HL007605-40