Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada; Harvard T H Chan School of Public Health, Harvard University, Boston, MA, USA.
Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada.
Lancet Planet Health. 2024 Apr;8(4):e256-e269. doi: 10.1016/S2542-5196(24)00030-5.
Health agencies worldwide have historically cautioned that electric fans accelerate body-heat gain during hot weather and heatwaves (typically in air temperatures ≥35°C). However, guidance published since 2021 has suggested that fans can still cool the body in air temperatures up to 40°C by facilitating sweat evaporation, and therefore are an inexpensive yet sustainable alternative to air conditioning. In a critical analysis of the reports cited to support this claim, we found that although fan use improves sweat evaporation, these benefits are of insufficient magnitude to exert meaningful reductions in body core temperature in air temperatures exceeding 35°C. Health agencies should continue to advise against fan use in air temperatures higher than 35°C, especially for people with compromised sweating capacity (eg, adults aged 65 years or older). Improving access to ambient cooling strategies (eg, air conditioning or evaporative coolers) and minimising their economic and environmental costs through policy initiatives, efficient cooling technology, and combined use of low-cost personal interventions (eg, skin wetting or fan use) are crucial for climate adaptation.
全球卫生机构历来警告说，电扇在炎热天气和热浪期间（通常在气温≥35°C 时）会加速身体热量积聚。然而，自 2021 年以来发布的指南表明，电扇仍然可以通过促进汗液蒸发来使身体在气温高达 40°C 的情况下降温，因此是空调的一种廉价且可持续的替代品。在对支持这一说法的报告进行的批判性分析中，我们发现，尽管使用电扇可以改善汗液蒸发，但这些益处的幅度不足以在气温超过 35°C 时对身体核心温度产生有意义的降低。卫生机构应继续建议在气温高于 35°C 时不要使用电扇，尤其是对于排汗能力受损的人（例如，65 岁或以上的成年人）。通过政策举措、高效冷却技术以及低成本个人干预措施（例如，皮肤湿润或使用电扇）的综合使用，改善环境冷却策略（例如，空调或蒸发冷却器）的获取并降低其经济和环境成本对于气候适应至关重要。
