title: Unusually cold and dry winters increase mortality in Australia.
abstract: Seasonal patterns in mortality have been recognised for decades, with a marked excess of deaths in winter, yet our understanding of the causes of this phenomenon is not yet complete. Research has shown that low and high temperatures are associated with increased mortality independently of season; however, the impact of unseasonal weather on mortality has been less studied. In this study, we aimed to determine if unseasonal patterns in weather were associated with unseasonal patterns in mortality. We obtained daily temperature, humidity and mortality data from 1988 to 2009 for five major Australian cities with a range of climates. We split the seasonal patterns in temperature, humidity and mortality into their stationary and non-stationary parts. A stationary seasonal pattern is consistent from year-to-year, and a non-stationary pattern varies from year-to-year. We used Poisson regression to investigate associations between unseasonal weather and an unusual number of deaths. We found that deaths rates in Australia were 20-30% higher in winter than summer. The seasonal pattern of mortality was non-stationary, with much larger peaks in some winters. Winters that were colder or drier than a typical winter had significantly increased death risks in most cities. Conversely summers that were warmer or more humid than average showed no increase in death risks. Better understanding the occurrence and cause of seasonal variations in mortality will help with disease prevention and save lives.
authors.affiliation: Centre for Environment and Population Health, School of Environment, Griffith University, Brisbane, Qld. 4111, Australia; School of Public Health, Sun Yat-sen University, 74 Zhongshan Road #2, Guangzhou, Guangdong Province 510080, China. Electronic address: huangcunrui@hotmail.com.
authors.forename: Cunrui
authors.initials: C
authors.lastname: Huang
authors.affiliation: Centre for Environment and Population Health, School of Environment, Griffith University, Brisbane, Qld. 4111, Australia.
authors.forename: Cordia
authors.initials: C
authors.lastname: Chu
authors.affiliation: CSIRO Climate Adaptation Flagship and CSIRO Ecosystem Sciences, Commonwealth Scientific and Industrial Research Organisation, Melbourne, Vic. 3190, Australia.
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Wang
authors.affiliation: Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Qld. 4059, Australia.
authors.forename: Adrian G
authors.initials: AG
authors.lastname: Barnett
mesh_terms: D001315:Australia / Q000453:epidemiology; D002980:Climate; D003080:Cold Temperature; D006801:Humans; D009026:Mortality; D012621:Seasons
keywords: Climate change; Humidity; Mortality; Season; Temperature