Cohort-based long-term ozone exposure-associated mortality risks with adjusted metrics: A systematic review and meta-analysis

Haitong Zhe Sun; Pei Yu; Changxin Lan; Michelle W L Wan; Sebastian Hickman; Jayaprakash Murulitharan; Huizhong Shen; Le Yuan; Yuming Guo; Alexander T Archibald

doi:10.1016/j.xinn.2022.100246

Cohort-based long-term ozone exposure-associated mortality risks with adjusted metrics: A systematic review and meta-analysis

Innovation (Camb). 2022 Apr 20;3(3):100246. doi: 10.1016/j.xinn.2022.100246. eCollection 2022 May 10.

Authors

Haitong Zhe Sun^{1

2}, Pei Yu³, Changxin Lan^{4

5}, Michelle W L Wan¹, Sebastian Hickman¹, Jayaprakash Murulitharan¹, Huizhong Shen⁶, Le Yuan¹, Yuming Guo³, Alexander T Archibald^{1

7}

Affiliations

¹ Centre for Atmospheric Science, Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, UK.
² Department of Earth Sciences, University of Cambridge, Cambridge CB2 3EQ, UK.
³ School of Public Health and Preventive Medicine, Monash University, Melbourne, VIC 3004, Australia.
⁴ Institute of Reproductive and Child Health, Key Laboratory of Reproductive Health, National Health Commission of the People's Republic of China, Beijing 100191, China.
⁵ Department of Epidemiology and Biostatistics, School of Public Health, Peking University, Beijing 100191, China.
⁶ School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China.
⁷ National Centre for Atmospheric Science, Cambridge CB2 1EW, UK.

Abstract

Long-term ozone (O₃) exposure may lead to non-communicable diseases and increase mortality risk. However, cohort-based studies are relatively rare, and inconsistent exposure metrics impair the credibility of epidemiological evidence synthetization. To provide more accurate meta-estimations, this study updates existing systematic reviews by including recent studies and summarizing the quantitative associations between O₃ exposure and cause-specific mortality risks, based on unified exposure metrics. Cross-metric conversion factors were estimated linearly by decadal observations during 1990-2019. The Hunter-Schmidt random-effects estimator was applied to pool the relative risks. A total of 25 studies involving 226,453,067 participants (14 unique cohorts covering 99,855,611 participants) were included in the systematic review. After linearly unifying the inconsistent O₃ exposure metrics , the pooled relative risks associated with every 10 nmol mol^-1 (ppbV) incremental O₃ exposure, by mean of the warm-season daily maximum 8-h average metric, were as follows: 1.014 with 95% confidence interval (CI) ranging 1.009-1.019 for all-cause mortality; 1.025 (95% CI: 1.010-1.040) for respiratory mortality; 1.056 (95% CI: 1.029-1.084) for COPD mortality; 1.019 (95% CI: 1.004-1.035) for cardiovascular mortality; and 1.074 (95% CI: 1.054-1.093) for congestive heart failure mortality. Insignificant mortality risk associations were found for ischemic heart disease, cerebrovascular diseases, and lung cancer. Adjustment for exposure metrics laid a solid foundation for multi-study meta-analysis, and widening coverage of surface O₃ observations is expected to strengthen the cross-metric conversion in the future. Ever-growing numbers of epidemiological studies supported the evidence for considerable cardiopulmonary hazards and all-cause mortality risks from long-term O₃ exposure. However, evidence of long-term O₃ exposure-associated health effects was still scarce, so more relevant studies are needed to cover more populations with regional diversity.

Publication types

Review