Temperature Variability and Mortality: A Multi-Country Study

Abstract

Background:The evidence and method are limited for the associations between mortality and temperature variability (TV) within or between days.Objectives:We developed a novel method to calculate TV and investigated TV-mortality associations using a large multicountry data set.Methods:We collected daily data for temperature and mortality from 372 locations in 12 countries/regions (Australia, Brazil, Canada, China, Japan, Moldova, South Korea, Spain, Taiwan, Thailand, the United Kingdom, and the United States). We calculated TV from the standard deviation of the minimum and maximum temperatures during the exposure days. Two-stage analyses were used to assess the relationship between TV and mortality. In the first stage, a Poisson regression model allowing over-dispersion was used to estimate the community-specific TV-mortality relationship, after controlling for potential confounders. In the second stage, a meta-analysis was used to pool the effect estimates within each country.Results:There was a significant association between TV and mortality in all countries, even after controlling for the effects of daily mean temperature. In stratified analyses, TV was still significantly associated with mortality in cold, hot, and moderate seasons. Mortality risks related to TV were higher in hot areas than in cold areas when using short TV exposures (0–1 days), whereas TV-related mortality risks were higher in moderate areas than in cold and hot areas when using longer TV exposures (0–7 days).Conclusions:The results indicate that more attention should be paid to unstable weather conditions in order to protect health. These findings may have implications for developing public health policies to manage health risks of climate change.Citation:Guo Y, Gasparrini A, Armstrong BG, Tawatsupa B, Tobias A, Lavigne E, Coelho MS, Pan X, Kim H, Hashizume M, Honda Y, Guo YL, Wu CF, Zanobetti A, Schwartz JD, Bell ML, Overcenco A, Punnasiri K, Li S, Tian L, Saldiva P, Williams G, Tong S. 2016. Temperature variability and mortality: a multi-country study. Environ Health Perspect 124:1554–1559; http://dx.doi.org/10.1289/EHP149

How Does Ambient Air Temperature Affect Diabetes Mortality in Tropical Cities?

“…We used 4 df for both lag and temperature dimensions in the cross-basis term, since it has the lowest QAIC value from among the various simulated combinations of both lag and temperature with each ranging from 4 to 20 df (see Supplementary Materials Table S1), respectively, which are supported by previous studies [9,10,11,12]. Seven degrees of freedom per year was used for time trends [10,11,13,33], while 3 df was used for RHave ; both are in concurrence with previously published studies.…”

Heat or Cold: Which One Exerts Greater Deleterious Effects on Health in a Basin Climate City? Impact of Ambient Temperature on Mortality in Chengdu, China

“…On the one hand, the winter excess mortality is changing over time but, on the other, indoor heating can relieve the threat of cold in a certain degree. A recent study suggests that, although unstable weather is a continuous process, impacts on health may be better captured by considering the temperature variability when assessing the associations between temperature and human health [36]. Only time will reveal exactly how climate change-related shifts in temperature distributions will affect mortality trends.…”

Changing rapid weather variability increases influenza epidemic risk in a warming climate

“…It has been proposed that sudden large changes in temperature can impair the human immune system and trigger immune evasion [24][25][26][27][28][29]. The possible mechanism is that the human thermoregulation of immune defense is less adjustable to the sudden large change in temperature [26,27] and less resistant to various diseases [24,25].…”

“…It has been proposed that sudden large changes in temperature can impair the human immune system and trigger immune evasion [24][25][26][27][28][29]. The possible mechanism is that the human thermoregulation of immune defense is less adjustable to the sudden large change in temperature [26,27] and less resistant to various diseases [24,25]. Recently, studies showed that the sudden large change in temperature tends to cause high respiratory mortality [24][25][26][27]30] and to impact influenza seasonality [31].…”

“…The possible mechanism is that the human thermoregulation of immune defense is less adjustable to the sudden large change in temperature [26,27] and less resistant to various diseases [24,25]. Recently, studies showed that the sudden large change in temperature tends to cause high respiratory mortality [24][25][26][27]30] and to impact influenza seasonality [31]. It is, in fact, based on this pathological mechanism that we suspect that frequent fluctuating weather, as an additional factor, may play a significant role in influenza epidemics.…”