ORIGINAL RESEARCH article
Front. Public Health
Sec. Environmental Health and Exposome
Volume 13 - 2025 | doi: 10.3389/fpubh.2025.1652961
Associations between apparent temperatures and emergency ambulance calls in Wuxi, China: a time series analysis
Provisionally accepted
- 1Wuxi Center for Disease Control and Prevention, Wuxi, China
- 2School of Public Health, Nanjing Medical University, Nanjing, China
- 3Statistics and Information Center of Wuxi Health Commission, Wuxi, China
- 4The Affiliated Wuxi Center for Disease Control and Prevention of Nanjing Medical University, Wuxi, China
- 5Nanjing Medical University, Nanjing, China
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Inappropriate apparent temperature (AT) is a major global threat to human health. Although the association between temperature and health has been studied extensively, limited evidence regarding emergency ambulance calls (EACs) is available. Daily emergency department visit records, meteorological data, and air pollutant data were obtained from 1 January 2014 to 31 December 2019. A distributed lag non-linear model was applied to examine the interaction between AT and lagged effects. The analysis was stratified according to disease aetiology, sex, and age. The proportion of EACs attributable to AT was calculated as an indicator of associated burden. A non-linear U-shaped relationship was observed between AT and non-accidental, cardiovascular, and circulatory EACs, with the lowest risk AT occurring at 22.54°C, 17.12°C, and 12.74°C, respectively. High AT effects manifested immediately, whereas low AT effects were delayed. Stratified analysis indicated that males and individuals aged ≥65 years demonstrated heightened sensitivity to both extreme heat (97.5th percentile, 35.98°C) and cold (2.5th percentile, -1.27°C), whereas females displayed greater vulnerability to extreme heat (relative risks = 1.16, 95% confidence intervals [CI]: 1.04-1.29). The attributable fraction (AF) for non-accidental EACs in Wuxi was 6.88% (95% CI: 4.09%-9.26%), with higher AFs observed for cardiovascular (10.37%) and respiratory (4.94%) emergencies. Moderate thermal variations substantially affected the EACs more than extreme AT conditions. These findings underscore the necessity of implementing early warning mechanisms targeting thermal extremes and developing temperatureregulated public facilities to safeguard vulnerable groups, particularly older citizens, during extreme temperature events.
Keywords: Apparent temperature, Emergency ambulance calls, Extreme temperatures, Attributable risk, time series analysis
Received: 24 Jun 2025; Accepted: 25 Aug 2025.
Copyright: © 2025 Yang, Li, Zhang, Tao, Zhu, Lu, Zhou and Ding. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Xinliang Ding, Wuxi Center for Disease Control and Prevention, Wuxi, China
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