The impact of short-term ambient air pollution on CPAP therapy outcomes in obstructive sleep apnea.

PURPOSE: To determine whether short-term exposure to ambient air pollution adversely impacts the effectiveness of CPAP therapy in patients with diagnosed Obstructive Sleep Apnea (OSA).

METHODS

In a retrospective cohort study of 185 patients with diagnosed OSA using CPAP therapy, we analyzed the associations between daily levels of Particulate Matter (PM2.5), PM10, Black Carbon (BC) and Nitric Oxide (NO₂) and three primary outcomes: Continuous Positive Airway Pressure (CPAP) usage duration (minutes/night), AHI (events/hour) and mask leakage. Distributed lag non-linear models were used to assess lagged effects (lags 0-7 days), adjusting for confounders, seasonality and long-term trends. Subgroup analyses were conducted based on sex and CPAP compliance levels.

RESULTS

Statistically significant inverse associations were observed between air pollution and nightly CPAP usage (e.g., a 0.5 µg/m³ increase in BC was associated with a reduction of 4.6 min per night). Effects were cumulative across several days, with no significant impact on single-day exposures. No clinically meaningful associations were observed for residual AHI or mask leakage. Subgroup analyses suggested slightly stronger reductions in women and high-adherence users, but these effects remained small.

CONCLUSION

Short-term exposure to ambient air pollution is associated with minor reductions in CPAP usage; however, the effect size is small and unlikely to be clinically significant in a low-pollution settings. CPAP effectiveness, as measured by residual AHI and mask performance, appears unaffected. These findings suggest that CPAP therapy remains robust despite typical variations in environmental air quality, and the clinical relevance of pollution-driven adherence changes is limited.