Evidence map›Paper›PMID 40691071›Full record

ArticleEnvironmental health and preventive medicine2025

Association between outdoor temperature and bath-related drowning deaths in Japan (1995-2020): modifying factors and the role of prefectural characteristics.

Yoshiaki Tai, Kenji Obayashi, Yuki Yamagami, Keigo Saeki

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Article in Environmental health and preventive medicine, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 2 papers.

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3 · Its place in the literature

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2 citing papers in PubMed.

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4 · The record

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5 · Who and what money

Authors and funding

4 authors.

Yoshiaki TaiDepartment of Epidemiology, Nara Medical University School of Medicine.ORCID http://orcid.org/0000-0001-6204-113X
Kenji ObayashiDepartment of Epidemiology, Nara Medical University School of Medicine.
Yuki YamagamiDepartment of Epidemiology, Nara Medical University School of Medicine.
Keigo SaekiDepartment of Epidemiology, Nara Medical University School of Medicine.

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

backgroundOlder adults in Japan have the highest drowning mortality rate globally due to frequent bathing practices. Low outdoor temperatures have been linked to bath-related deaths; however, previous studies employed limited statistical models and focused on a single prefecture. Given Japan's aging population, preventing bath-related deaths is a public health priority. This study aimed to analyze the association between outdoor temperature and bath-related drowning deaths across Japan from 1995 to 2020 (n = 110,938), examining regional variations and identifying contributing prefectural characteristics.

methodsDaily counts of bath-related drowning deaths per prefecture were matched with daily mean temperature data from the Japan Meteorological Agency. Prefecture-level demographic and environmental data were obtained from Japan's Official Statistics. We applied a generalized additive mixed model to examine the association between daily mean temperature and bath-related drowning death risk. Meta-regression was used to identify prefecture-level modifiers.

resultsBath-related drowning death risk peaked at a daily mean temperature of 1.8 °C (relative risk [RR] 9.7, 95% confidence interval [CI]: 9.5-9.9), compared with the lowest risk at 30.3 °C. The association was stronger at mid-range temperatures, particularly among males and individuals aged ≥65 years. Among prefectures, Kagoshima-the southernmost prefecture on Japan's main islands-had the highest maximum RR at 19.6 (95% CI: 16.2-23.6), while Hokkaido-the northernmost prefecture-had the lowest at 3.8 (95% CI: 3.4-4.3). Prefecture-level factors that strengthened this relationship included a lower prevalence of double-pane windows as a proxy of housing insulation and higher annual mean temperatures with ratio of RR change per one standard deviation increase of 0.76 (95% CI: 0.69-0.83) and 1.27 (95% CI: 1.18-1.37), respectively.

conclusionsWarmer prefectures in southern regions exhibited greater maximum-to-minimum risk ratios compared to cooler northern prefectures. This paradoxical finding underscores the importance of region-specific interventions to reduce bath-related deaths.

Indexed as

BathsDrowningTemperatureAdolescentAdultAgedAged, 80 and overFemaleHumansJapanMaleMiddle AgedRisk FactorsYoung AdultAccidental drowningBath-related deathsHousing insulationOlder populationOutdoor temperature

Identifiers

PMID40691071
PMCPMC12301073

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.