Heat and ozone together are associated with higher mortality risk
Pooled studies linked simultaneous heat and high ozone with higher mortality, but inconsistent definitions and possible confounding limit interpretation.
Based on the published abstract. The full paper may contain additional methods, results and limitations.
The 30-second takeaway
The pooled evidence associated combined heat and high ozone with greater mortality risk than situations without that combination. Observational associations cannot establish causation. Differences in study settings, exposure definitions and adjustment for other factors limit how precisely this estimate applies to a particular place or person.
Some studies inadequately accounted for potential confounders, and handling of missing data was unclear. Definitions of combined events, outcomes and study settings varied, limiting interpretation of this abstract-based summary.
What researchers found
Pooled relative risk (RR) of overall mortality
Combined heat and high ozone versus no combined exposure; exposure and follow-up periods were not reported. RR compares risks between groups; it does not give the absolute chance of death, which the abstract omits.
What the comparison establishes
The comparison category lacked the combined exposure scenario. The abstract does not describe a consistent comparison against heat alone or ozone alone, so the pooled result cannot isolate the additional effect of their combination.
Other mortality outcomes
The review also reported higher cardiovascular and respiratory mortality estimates. Associations appeared across age and gender groups and in urban areas, but the abstract provides limited detail about those comparisons.
The original publication
Effect of compound heat and ozone events on health outcomes: a systematic review and meta-analysis of epidemiological evidence.
Wang Y, Ho JY, Guo Y et al.
Environ Pollut · 2026
- PubMed ID
- 41422906
- Record checked
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