Long-term exposure to ambient ozone and adult-onset asthma: A prospective cohort study

Jiayue Zhang; Baozhuo Ai; Yuming Guo; Lan Chen; Ge Chen; Haitao Li; Hualiang Lin; Zilong Zhang

doi:10.1016/j.envres.2024.118962

Long-term exposure to ambient ozone and adult-onset asthma: A prospective cohort study

Environ Res. 2024 Apr 19;252(Pt 2):118962. doi: 10.1016/j.envres.2024.118962. Online ahead of print.

Authors

Jiayue Zhang¹, Baozhuo Ai¹, Yuming Guo², Lan Chen¹, Ge Chen¹, Haitao Li³, Hualiang Lin⁴, Zilong Zhang⁵

Affiliations

¹ Department of Epidemiology, School of Public Health, Sun Yat-sen University, Guangzhou, 510080, China.
² School of Public Health and Preventive Medicine, Monash University, Melbourne, VIC, 3004, Australia.
³ Department of Social Medicine and Health Service Management, Health Science Center, Shenzhen University, Shenzhen, 518055, China.
⁴ Department of Epidemiology, School of Public Health, Sun Yat-sen University, Guangzhou, 510080, China. Electronic address: linhualiang@mail.sysu.edu.cn.
⁵ Department of Epidemiology, School of Public Health, Sun Yat-sen University, Guangzhou, 510080, China. Electronic address: zhangzilong@mail.sysu.edu.cn.

PMID: 38642637
DOI: 10.1016/j.envres.2024.118962

Abstract

Background: The association between long-term exposure to ozone (O₃) and adult-onset asthma (AOA) remains inconclusive, and analysis of causality is lacking.

Objectives: To examine the causal association between long-term O₃ exposure and AOA.

Methods: A prospective cohort study of 362,098 participants was conducted using the UK Biobank study. Incident cases of AOA were identified using health administrative data of the National Health Services. O₃ exposure at participants' residential addresses was estimated by a spatio-temporal model. Instrumental variable (IV) modelling was used to analyze the causal association between O₃ exposure and AOA, by incorporating wind speed and planetary boundary layer height as IVs into time-dependent Cox model. Negative control outcome (accidental injury) was also used to additionally evaluate unmeasured confounding.

Results: During a mean follow-up of 11.38 years, a total of 10,973 incident AOA cases were identified. A U-shaped concentration-response relationship was observed between O₃ exposure and AOA in the traditional Cox models with HR of 0.916 (95% CI: 0.888, 0.945) for O₃ at low levels (<38.17 ppb), and 1.204 (95% CI: 1.168, 1.242) for O₃ at high levels (≥38.17 ppb). However, in the IV analysis we only found a statistically significant association between high-level O₃ exposure and AOA risk, but not for low-level O₃ exposure. No significant associations between O₃ exposure and accidental injury were observed.

Conclusion: Our findings suggest a potential causal relationship between long-term exposure to high-level ambient O₃ and increased risks of AOA.

Keywords: Adult-onset asthma; Causal relationship; Long-term exposure; Ozone.