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Author Notes:

Address correspondence to Yoonhee Kim, Department of Global Environmental Health, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan. Telephone: (81) 3 5841 3582. Email: yoonheekim@m.u-tokyo.ac.jp

The authors declare they have no actual or potential competing financial interests.


Research Funding:

This study was partly supported by the Global Research Lab (K21004000001-10A0500-00710) the Mid-Career Research grant (2019R1A2C1086194) of the National Research Foundation, the Ministry of Science, Information and Communication Technologies in South Korea; by the Medical Research Council UK (MR/M022625/1 and MR/R013349/1) and the Natural Environment Research Council (NE/R0093894/1) in the UK; by the National Institutes of Health/National Institute of Environmental Health Sciences–funded Health and Exposome Research Center at Emory (HERCULES) Center (P30ES019776) and the USEPA grant RD-83587201 in the United States; by the National Health Research Institute (NHRI-EM-106-SP03) in Taiwan; by the Environment Research and Technology Development Fund (S-14) of the Ministry of the Environment in Japan; by the Joint Usage/Research Center on Tropical Disease, Institute of Tropical Medicine, School of Tropical Medicine and Global Health, Nagasaki University in Japan; by the Japan Society for the Promotion of Science (JSPS) Invitational Fellowships for Research (S18149) in Japan; and by the JSPS Grants-in-Aid for Scientific Research (KAKENHI; JP16K19773, JP19K17104, and 19H03900) in Japan.


  • Science & Technology
  • Life Sciences & Biomedicine
  • Environmental Sciences
  • Public, Environmental & Occupational Health
  • Toxicology
  • Environmental Sciences & Ecology

Suicide and Ambient Temperature: A Multi-Country Multi-City Study

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Journal Title:



Volume 127, Number 11


, Pages 117007-117007

Type of Work:

Article | Final Publisher PDF


BACKGROUND: Previous literature suggests that higher ambient temperature may play a role in increasing the risk of suicide. However, no multicountry study has explored the shape of the association and the role of moderate and extreme heat across different locations. OBJECTIVES: We examined the short-term temperature–suicide relationship using daily time-series data collected for 341 locations in 12 countries for periods ranging from 4 to 40 y. METHODS: We conducted a two-stage meta-analysis. First, we performed location-specific time-stratified case-crossover analyses to examine the temperature–suicide association for each location. Then, we used a multivariate meta-regression to combine the location-specific lag-cumulative nonlinear associations across all locations and by country. RESULTS: A total of 1,320,148 suicides were included in this study. Higher ambient temperature was associated with an increased risk of suicide in general, and we observed a nonlinear association (inverted J-shaped curve) with the highest risk at 27°C. The relative risk (RR) for the highest risk was 1.33 (95% CI: 1.30, 1.36) compared with the risk at the first percentile. Country-specific results showed that the nonlinear associations were more obvious in northeast Asia (Japan, South Korea, and Taiwan). The temperature with the highest risk of suicide ranged from the 87th to 88th percentiles in the northeast Asian countries, whereas this value was the 99th percentile in Western countries (Canada, Spain, Switzerland, the UK, and the United States) and South Africa, where nearly linear associations were estimated. The country-specific RRs ranged from 1.31 (95% CI: 1.19, 1.44) in the United States to 1.65 (95% CI: 1.40, 1.93) in Taiwan, excluding countries where the results were substantially uncertain. DISCUSSION: Our findings showed that the risk of suicide increased with increasing ambient temperature in many countries, but to varying extents and not necessarily linearly. This temperature–suicide association should be interpreted cautiously, and further evidence of the relationship and modifying factors is needed. https://doi.org/10.1289/EHP4898.

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© 2019, Public Health Services, US Dept of Health and Human Services. All rights reserved.

This is an Open Access work distributed under the terms of the Creative Commons Universal : Public Domain Dedication License (https://creativecommons.org/publicdomain/zero/1.0/).
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