The joint association of ambient air pollution and different sleep posture with mild obstructive sleep apnea: A study conducted at Taipei Sleep Center

Background: Growing evidence suggests the detrimental impact of supine position and air pollution on obstructive sleep apnea (OSA), as well as the potential benefits of nonsupine positions. However, their interaction effects on OSA remain unclear. Objectives: To evaluate the interaction effects of air pollution (NO₂/PM_2.5) and sleep position on OSA on additive and multiplicative scales. Methods: This study included 3330 individuals. Personal exposure to air pollution was assessed using a spatiotemporal model. OSA was diagnosed through polysomnography. The associations of supine and nonsupine positions and air pollutants with mild-OSA and their interaction effects on mild-OSA. were explored through generalized logistic regression. Results: Supine position and high NO₂ level independently increased the risk of mild-OSA, while PM_2.5 was not associated with mild-OSA. Significant interactions were observed between supine position and NO₂ at different lag periods (0–7 days, 0–1 year, and 0–2 years) (P = 0.042, 0.013, and 0.010, respectively). The relative excess risks due to interactions on the additive scale for 1-week, 1-year, and 2-year NO₂ exposure and supine position were 0.63 (95 % CI: 0.10–1.16), 0.56 (95 % CI: 0.13–0.99), and 0.64 (95 % CI: 0.18–1.10); the corresponding odds ratios for interactions on the multiplicative scale were 1.45 (95 % CI: 1.01–2.07), 1.55 (95 % CI: 1.09–2.22), and 1.60 (95 % CI: 1.12–2.28). The positive interactions persisted in men and participants with obesity. No interaction was observed between nonsupine position and NO₂ levels; nevertheless, significant interactions were noted on both the negative additive and multiplicative scales in men. Conclusion: Prolonged supine sleep significantly increased the risk of mild-OSA, particularly in men and individuals with obesity. Although the benefits of nonsupine position are considerably less than the risks of NO₂ exposure, avoiding prolonged supine sleep may reduce the risk of mild-OSA caused by high levels of NO₂ in men.