Effect of ambient ozone and its interactions with ambient PM2.5 and temperature on peak expiratory flow in adults with asthma

Abstract

Numerous studies have linked air pollution to asthma. However, limited information exists on the effect of ambient ozone (O₃), or its interactions with fine particulate matter (PM_2.5) or temperature on peak expiratory flow (PEF) of in asthmatic adults. We conducted a longitudinal study including 99 adult asthma patients and documenting 7153 person-days PEF records. Utilizing linear mixed-effect and distributed non-linear models, we investigated the associations between ambient O₃ exposures over lag0-14 days with morning and evening PEF, as well as diurnal PEF variability. Findings revealed significant associations between ambient O₃ exposure with reduced morning and evening PEF, with varied associations for exposures across different lag days. Specifically, the most pronounced association with morning PEF was found for exposure at lag4, with a change of −0.211 (95%CI: −0.360, −0.062) L/min per 10 μg/m³ increase; for evening PEF, the strongest association was observed for exposure at lag0, with a change of −0.379 (95%CI: −0.721, −0.037) L/min per 10 μg/m³ increase. However, no significant association between O₃ and diurnal PEF variability was found. Furthermore, we observed significant interactions between O₃ and PM_2.5 exposures from lag6 to lag9 on morning and evening PEF, and significant interactions between O₃ and temperature from lag1 to lag11 on morning PEF and from lag0 to lag11 on evening PEF. Stronger associations between O₃ and PEF were observed in males, those aged over 40 years, overweight individuals, smokers and those with non-allergic asthma. These results underscore considering combined pollution and climate impacts in asthma management and supporting policies.