The evidence concerning the association between ambient temperature and mortality is limited in developing countries, especially in China. We assessed the effects of temperature on daily mortality between 2005 and 2008 in Suzhou, China. A Poisson regression model combined with a distributed-lag nonlinear model was used to examine the association between temperature and daily mortality. We investigated effect modification by individual characteristics, including gender, age and educational attainment. We found significant non-linear effects of temperature on total and cardiovascular mortality. Heat effects were immediate and lasted for 1-2 days, whereas cold effects persisted for 10 days. The relative risk of total morality associated with extreme cold temperature (1st percentile of temperature, -0.3 °C) over lags 0-14 days was 1.75 [95% confidence interval (CI): 1.43, 2.14)], compared with the minimum mortality temperature (26 °C). The relative risk associated with extremely hot temperature (99th percentile of temperature, 32.6 °C) over lags 0-3 days was 1.43 (95% CI: 1.31, 1.56). We did not observe significant modifying effect by gender, age or educational level. This study showed that exposure to both hot and cold temperatures was associated with increased mortality in Suzhou. Our findings may have implications for developing intervention strategies for extreme cold and hot temperatures.
This research quantifies the lag effects and vulnerabilities of temperature effects on cardiovascular disease in Changsha--a subtropical climate zone of China. A Poisson regression model within a distributed lag nonlinear models framework was used to examine the lag effects of cold- and heat-related CVD mortality. The lag effect for heat-related CVD mortality was just 0-3 days. In contrast, we observed a statistically significant association with 10-25 lag days for cold-related CVD mortality. Low temperatures with 0-2 lag days increased the mortality risk for those ≥65 years and females. For all ages, the cumulative effects of cold-related CVD mortality was 6.6% (95% CI: 5.2%-8.2%) for 30 lag days while that of heat-related CVD mortality was 4.9% (95% CI: 2.0%-7.9%) for 3 lag days. We found that in Changsha city, the lag effect of hot temperatures is short while the lag effect of cold temperatures is long. Females and older people were more sensitive to extreme hot and cold temperatures than males and younger people.
BACKGROUND: Tibet, with an average altitude of more than 4,000 meters, is warming faster than anywhere else in China. However, there have been no studies in Tibet of the relation between ambient temperature and mortality.
METHODS: We examined mean temperature and daily mortality in three Tibetan counties (Chengguan, Jiangzi and Naidong) using a distributed lag non-linear model (DLNM) based on 5,610 deaths that occurred in 2008-2012. We separately investigated hot and cold effects on non-accidental deaths, cardiovascular deaths, out-of-hospital deaths and vulnerability factors including age, sex and education.
RESULTS: In all three counties, the effect of heat tended to be immediate, while the impact of cold lasted longer. The effects were consistent but modest in size and not statistically significant except for cumulative cold effects in Jiangzi (lag=0-14, RR=2.251, 95% CI=1.054-4.849). Those who were more vulnerable to temperature extremes tended to be men, the elderly (over 65 years) and illiterate persons. We found stronger temperature effects on cardiovascular deaths than on all-cause mortality, and we also observed an increase in out-of-hospital mortality in one county.
CONCLUSIONS: This is the first study to investigate the temperature-mortality relationship in Tibet, and the findings may guide public health programs and other interventions to protect the population against extreme temperatures in a developing Tibet.
BACKGROUND: Air temperature has been shown to be associated with mortality; however, only very few studies have been conducted in Germany. This study examined the association between daily air temperature and cause-specific mortality in Bavaria, Southern Germany. Moreover, we investigated effect modification by age and ambient air pollution.
METHODS: We obtained data from Munich, Nuremberg as well as Augsburg, Germany, for the period 1990 to 2006. Data included daily cause-specific death counts, mean daily meteorology and air pollution concentrations (particulate matter with a diameter<10 μm [PM10] and maximum 8-h ozone). We used Poisson regression models combined with distributed lag non-linear models adjusting for long-term trend, calendar effects, and meteorological factors. Air pollutant concentrations were categorized into three levels, and an interaction term was included to quantify potential effect modification of the air temperature effects.
RESULTS: The temperature-mortality relationships were non-linear for all cause-specific mortality categories showing U- or J-shaped curves. An increase from the 90th (20.0 °C) to the 99th percentile (24.8 °C) of 2-day average temperature led to an increase in non-accidental mortality by 11.4% (95% CI: 7.6%-15.3%), whereas a decrease from the 10th (-1.0 °C) to the 1st percentile (-7.5 °C) in the 15-day average temperature resulted in an increase of 6.2% (95% CI: 1.8%-10.8%). The very old were found to be most susceptible to heat effects. Results also suggested some effect modification by ozone, but not for PM10.
CONCLUSIONS: Results indicate that both very low and very high air temperature increase cause-specific mortality in Bavaria. Results also pointed to the importance of considering effect modification by age and ozone in assessing temperature effects on mortality.
Several studies have examined the relationship of high and low air temperatures to cardiovascular mortality in the Czech Republic. Much less is understood about heat-/cold-related cardiovascular morbidity and possible regional differences. This paper compares the effects of warm and cold days on excess mortality and morbidity for cardiovascular diseases (CVDs) in the city of Prague and a rural region of southern Bohemia during 1994-2009. Population size and age structure are similar in the two regions. The results are evaluated for selected population groups (men and women). Excess mortality (number of deaths) and morbidity (number of hospital admissions) were determined as differences between observed and expected daily values, the latter being adjusted for long-term changes, annual and weekly cycles, and epidemics of influenza/acute respiratory infections. Generally higher relative excess CVD mortality on warm days than on cold days was identified in both regions. In contrast to mortality, weak excess CVD morbidity was observed for both warm and cold days. Different responses of individual CVDs to heat versus cold stress may be caused by the different nature of each CVD and different physiological processes induced by heat or cold stress. The slight differences between Prague and southern Bohemia in response to heat versus cold stress suggest the possible influence of environmental and socioeconomic factors such as the effects of urban heat island and exposure to air pollution, lifestyle differences, and divergence in population structure, which may result in differing vulnerability of urban versus rural population to temperature extremes.
OBJECTIVES: To assess the heterogeneity of heatwave-related impacts on mortality across different cities.
DESIGN: A multicity time series study.
SETTING: 3 largest Australian cities: Brisbane, Melbourne and Sydney.
PARTICIPANTS: All residents living in these cities.
MAIN OUTCOME MEASURES: Non-external causes mortality data by gender and two age groups (ie, 0-75 and 75+) for these cities during the period 1988-2009 were obtained from relevant government agencies.
RESULTS: Total mortality increased mostly within the same day (lag 0) or a lag of 1 day (lag 1) during almost all heatwaves in three cities. Using the heatwave definition (HWD) as the 95th centile of mean temperature for two or more consecutive days in the summer season, the relative risk for total mortality at lag 1 in Brisbane, Melbourne and Sydney was 1.13 (95% CI 1.08 to 1.19), 1.10 (95% CI 1.06 to 1.14) and 1.06 (95% CI 1.01 to 1.10), respectively. Using the more stringent HWD-the 99th centile of mean temperature for two or more consecutive days, the relative risk of total mortality at the lags of 0-2 days in Brisbane and Melbourne was 1.40 (95% CI 1.29 to 1.51) and 1.47 (95% CI 1.36 to 1.59), respectively. Elderly, particularly females, were more vulnerable to the impact of heatwaves.
CONCLUSIONS: A consistent and significant increase in mortality was observed during heatwaves in the three largest Australian cities, but the impacts of heatwave appeared to vary with age, gender, the HWD and geographical area.
Air temperature and pollution can jointly affect human health. Submicrometer particles appearing to have particularly harmful effects compared with the coarse ones. However, little is known about how the association between temperature and mortality is affected by these particles. This study examined the association between air temperature and mortality before and after adjustment for particle concentrations among different age and disease groups from 1995 to 2000 in Brisbane, Australia. The monitoring of particle size distribution within the 15-750nm range was carried out by a Scanning Mobility Particle Sizer. Corresponding climate and air pollutant data were collected from relevant government agencies. The association between temperature and mortality was quantified using a Poisson time-series model within a distributed lag non-linear modelling framework. The results showed that the effects of air temperature on mortality were lower among the elderly and people with respiratory diseases, and greater among people with cardiovascular diseases after controlling for submicrometer particle concentrations. Submicrometer particles seem to be an important confounder for the temperature-mortality relationship, particularly among vulnerable groups, and should be taken into account when assessing the impacts of air temperature on human health.
BACKGROUND: Ambient temperatures can cause an increase in mortality. A better understanding is needed of how health status and other factors modify the risk associated with high and low temperatures, to improve the basis of preventive measures. Differences in susceptibility to temperature and to heat and cold wave duration are relatively unexplored.
OBJECTIVES: We studied the associations between mortality and temperature and heat and cold wave duration, stratified by age and individual and medical factors.
METHODS: Deaths among all residents of Stockholm County between 1990 and 2002 were linked to discharge diagnosis data from hospital admissions, and associations were examined using the time stratified case-crossover design. Analyses were stratified by gender, age, pre-existing disease, country of origin, and municipality level wealth, and adjusted for potential confounding factors. Results : The effect on mortality by heat wave duration was higher for lower ages, in areas with lower wealth, for hospitalized patients younger than age 65. Odds were elevated among females younger than age 65, in groups with a previous hospital admission for mental disorders, and in persons with previous cardiovascular disease. Gradual increases in summer temperatures were associated with mortality in people older than 80 years, and with mortality in groups with a previous myocardial infarction and with chronic obstructive pulmonary disease (COPD) in the population younger than 65 years. During winter, mortality was associated with a decrease in temperature particularly in men and with the duration of cold spells for the population older than 80. A history of hospitalization for myocardial infarction increased the odds associated with cold temperatures among the population older than 65. Previous mental disease or substance abuse increased the odds of death among the population younger than 65.
CONCLUSION: To increase effectiveness, we suggest preventive efforts should not assume susceptible groups are the same for warm and cold days and heat and cold waves, respectively.
A substantial number of epidemiological studies have demonstrated an association between atmospheric conditions and human all-cause as well as cause-specific mortality. However, most research has been performed in industrialised countries, whereas little is known about the atmosphere-mortality relationship in developing countries. Especially with regard to modifications from non-atmospheric conditions and intra-population differences, there is a substantial research deficit. Within the scope of this study, we aimed to investigate the effects of heat in a multi-stratified manner, distinguishing by the cause of death, age, gender, location and socio-economic status. We examined 22,840 death counts using semi-parametric Poisson regression models, adjusting for a multitude of potential confounders. Although Bangladesh is dominated by an increase of mortality with decreasing (equivalent) temperatures over a wide range of values, the findings demonstrated the existence of partly strong heat effects at the upper end of the temperature distribution. Moreover, the study demonstrated that the strength of these heat effects varied considerably over the investigated subgroups. The adverse effects of heat were particularly pronounced for males and the elderly above 65 years. Moreover, we found increased adverse effects of heat for urban areas and for areas with a high socio-economic status. The increase in, and acceleration of, urbanisation in Bangladesh, as well as the rapid aging of the population and the increase in non-communicable diseases, suggest that the relevance of heat-related mortality might increase further. Considering rising global temperatures, the adverse effects of heat might be further aggravated.
BACKGROUND: Heat and air pollution are both associated with increases in mortality. However, the interactive effect of temperature and air pollution on mortality remains unsettled. Similarly, the relationship between air pollution, air temperature, and social deprivation has never been explored.
METHODS: We used daily mortality data from 2004 to 2009, daily mean temperature variables and relative humidity, for Paris, France. Estimates of chronic exposure to air pollution and social deprivation at a small spatial scale were calculated and split into three strata. We developed a stratified Poisson regression models to assess daily temperature and mortality associations, and tested the heterogeneity of the regression coefficients of the different strata. Deaths due to ambient temperature were calculated from attributable fractions and mortality rates were estimated.
RESULTS: We found that chronic air pollution exposure and social deprivation are effect modifiers of the association between daily temperature and mortality. We found a potential interactive effect between social deprivation and chronic exposure with regards to air pollution in the mortality-temperature relationship.
CONCLUSION: Our results may have implications in considering chronically polluted areas as vulnerable in heat action plans and in the long-term measures to reduce the burden of heat stress especially in the context of climate change.
The evidence concerning the association between ambient temperature and mortality is limited in developing countries, especially in China. We assessed the effects of temperature on daily mortality between 2005 and 2008 in Suzhou, China. A Poisson regression model combined with a distributed-lag nonlinear model was used to examine the association between temperature and daily mortality. We investigated effect modification by individual characteristics, including gender, age and educational attainment. We found significant non-linear effects of temperature on total and cardiovascular mortality. Heat effects were immediate and lasted for 1-2 days, whereas cold effects persisted for 10 days. The relative risk of total morality associated with extreme cold temperature (1st percentile of temperature, -0.3 °C) over lags 0-14 days was 1.75 [95% confidence interval (CI): 1.43, 2.14)], compared with the minimum mortality temperature (26 °C). The relative risk associated with extremely hot temperature (99th percentile of temperature, 32.6 °C) over lags 0-3 days was 1.43 (95% CI.: 1.31, 1.56). We did not observe significant modifying effect by gender, age or educational level. This study showed that exposure to both hot and cold temperatures was associated with increased mortality in Suzhou. Our findings may have implications for developing intervention strategies for extreme cold and hot temperatures.
