Nonlinear exposure-response associations of daytime, nighttime, and day-night compound heatwaves with mortality amid climate change

• DOI: 10.1038/s41467-025-56067-7
• Publication Date: 2025-01-14T03:49:00Z
• Authors: Jiangdong Liu; Ho Kim; Masahiro Hashizume; Whanhee Lee; Yasushi Honda; Satbyul Estella Kim; Cheng He; Haidong Kan; Renjie Chen
• Keywords: Science; Q; Article

Abstract Heatwaves are commonly simplified as binary variables in epidemiological studies, limiting the understanding of heatwave-mortality associations. Here we conduct a multi-country study across 28 East Asian cities that employed Cumulative Excess Heatwave Index (CEHWI), which represents excess heat accumulation during heatwaves, to explore potentially nonlinear associations daytime-only, nighttime-only, and day-night compound heatwaves with mortality from 1981 2010. Populations exhibited high adaptability daytime-only nighttime-only non-accidental risks increasing only at higher CEHWI levels (75th–90th percentiles). In contrast, posed super-linear increase after 25th percentile CEHWI. Associations cardiovascular mirrored those but were more pronounced levels, while significant respiratory emerged low-to-moderate levels. These results highlight necessity considering health responses different types disease burden assessments heatwave-health warning systems amid climate change.