Effects of temperature on mortality in Chiang Mai city, Thailand: a time series study
Yuming Guo1†, Kornwipa Punnasiri1,2† and Shilu Tong1*
Abstract
Background: The association between temperature and mortality has been examined mainly in North America and Europe. However, less evidence is available in developing countries, especially in Thailand. In this study, we examined the relationship between temperature and mortality in Chiang Mai city, Thailand, during 1999–2008.
Method: A time series model was used to examine the effects of temperature on cause-specific mortality (nonexternal, cardiopulmonary, cardiovascular, and respiratory) and age-specific non-external mortality (<=64, 65–74, 75–84, and>=85 years), while controlling for relative humidity, air pollution, day of the week, season and longterm trend. We used a distributed lag non-linear model to examine the delayed effects of temperature on mortality up to 21 days.
Results: We found non-linear effects of temperature on all mortality types and age groups. Both hot and cold temperatures resulted in immediate increase in all mortality types and age groups. Generally, the hot effects on all mortality types and age groups were short-term, while the cold effects lasted longer. The relative risk of nonexternal mortality associated with cold temperature (19.35°C, 1st percentile of temperature) relative to 24.7°C (25th percentile of temperature) was 1.29 (95% confidence interval (CI): 1.16, 1.44) for lags 0–21. The relative risk of nonexternal mortality associated with high temperature (31.7°C, 99th percentile of temperature) relative to 28°C (75th percentile of temperature) was 1.11 (95% CI: 1.00, 1.24) for lags 0–21.
Conclusion: This study indicates that exposure to both hot and cold temperatures were related to increased mortality. Both cold and hot effects occurred immediately but cold effects lasted longer than hot effects. This study provides useful data for policy makers to better prepare local responses to manage the impact of hot and cold temperatures on population health.
Keywords: Mortality, Cardiovascular, Respiratory, Temperature, Time series analysis
Guo et al. Environmental Health 2012, 11:36
http://www.ehjournal.net/content/11/1/36
* Correspondence:
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†Equal contributors
1School of Public Health, Queensland University of Technology, Kelvin Grove, Brisbane, Queensland, Australia
Full list of author information is available at the end of the article
