School of Public Health, Shanghai Institute of Infectious Disease and Biosecurity, Key Lab of Public Health Safety of the Ministry of Education and NHC Key Lab of Health Technology Assessment, Fudan University, Shanghai, China.
Department of Biostatistics and Epidemiology, Graduate School of Public Health, Seoul National University, Seoul, Republic of Korea.
Lancet Planet Health. 2022 Aug;6(8):e648-e657. doi: 10.1016/S2542-5196(22)00139-5.
The health impacts of climate warming are usually quantified based on daily average temperatures. However, extra health risks might result from hot nights. We project the future mortality burden due to hot nights.
We selected the hot night excess (HNE) to represent the intensity of night-time heat, which was calculated as the excess sum of high temperature during night time. We collected historical mortality data in 28 cities from three east Asian countries, from 1981 to 2010. The associations between HNE and mortality in each city were firstly examined using a generalised additive model in combination with a distributed lag non-linear model over lag 0-10 days. We then pooled the cumulative associations using a univariate meta-regression model at the national or regional levels. Historical and future hourly temperature series were projected under two scenarios of greenhouse-gas emissions from 1980-2099, with ten general circulation models. We then projected the attributable fraction of mortality due to HNE under each scenario.
Our dataset comprised 28 cities across three countries (Japan, South Korea, and China), including 9 185 598 deaths. The time-series analyses showed the HNE was significantly associated with increased mortality risks, the relative mortality risk on days with hot nights could be 50% higher than on days with non-hot nights. Compared with the rise in daily mean temperature (lower than 20%), the frequency of hot nights would increase more than 30% and the intensity of hot night would increase by 50% by 2100s. The attributable fraction of mortality due to hot nights was projected to be 3·68% (95% CI 1·20 to 6·17) under a strict emission control scenario (SSP126). Under a medium emission control scenario (SSP245), the attributable fraction of mortality was projected to increase up to 5·79% (2·07 to 9·52), which is 0·95% (-0·39 to 2·29) more than the attributable fraction of mortality due to daily mean temperature.
Our study provides evidence for significant mortality risks and burden in association with night-time warming across Japan, South Korea, and China. Our findings suggest a growing role of night-time warming in heat-related health effects in a changing climate.
The National Natural Science Foundation of China, Shanghai International Science and Technology Partnership Project.
通常根据日平均温度来量化气候变暖对健康的影响。然而，炎热的夜晚可能会带来额外的健康风险。我们预测未来因炎热夜晚导致的死亡人数。
我们选择热夜超额（HNE）来表示夜间热量的强度，该值通过计算夜间高温的总和来得出。我们收集了来自三个东亚国家的 28 个城市在 1981 年至 2010 年的历史死亡率数据。在每个城市中，首先使用广义加性模型结合分布滞后非线性模型，对 HNE 与死亡率之间的关系进行了检验，滞后时间为 0-10 天。然后，我们在国家或地区层面上使用单变量荟萃回归模型来汇总累积关联。根据 1980-2099 年温室气体排放的两种情景，对历史和未来的每小时温度序列进行了预测，其中使用了 10 个全球环流模型。然后，我们预测了每种情景下因 HNE 导致的死亡率的归因比例。
我们的数据集中包括来自三个国家（日本、韩国和中国）的 28 个城市，共包括 9185598 例死亡。时间序列分析表明，HNE 与死亡率升高有显著相关性，炎热夜晚的相对死亡率可能比非炎热夜晚高 50%。与日平均温度升高（低于 20℃）相比，到 21 世纪末，炎热夜晚的频率将增加 30%以上，炎热夜晚的强度将增加 50%。在严格的排放控制情景（SSP126）下，预计因炎热夜晚导致的死亡率归因比例为 3.68%（95%CI 1.20 至 6.17）。在中等排放控制情景（SSP245）下，预计死亡率归因比例将增加到 5.79%（2.07 至 9.52），比因日平均温度升高导致的死亡率归因比例高 0.95%（-0.39 至 2.29）。
本研究提供了证据表明，日本、韩国和中国各地的夜间升温与死亡率升高和负担显著相关。我们的研究结果表明，在气候变化中，夜间升温在与热有关的健康影响中发挥着越来越重要的作用。
国家自然科学基金，上海市国际科技合作项目。
