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Background: Although many studies have reported the mortality effect of temperature, there were few studies on the mortality risk of humidity, let alone the joint effect of temperature and humidity. This study aimed to investigate the joint and interaction effect of high temperature and relative humidity on mortality in China, which will deepen understanding the health risk of mixture climate exposure., Methods: The mortality and meteorological data were collected from 353 locations in China (2013-2017 in Jilin, Hunan, Guangdong and Yunnan provinces, 2009-2017 in Zhejiang province, and 2006-2011 in other Provinces). We defined location-specific daily mean temperature ≥ 75th percentile of distribution as high temperature, while minimum mortality relative humidity as the threshold of high relative humidity. A time-series model with a distributed lag non-linear model was first employed to estimate the location-specific associations between humid-hot events and mortality, then we conducted meta-analysis to pool the mortality effect of humid-hot events. Finally, an additive interaction model was used to examine the interactive effect between high temperature and relative humidity., Results: The excess rate (ER) of non-accidental mortality attributed to dry-hot events was 10.18% (95% confidence interval (CI): 8.93%, 11.45%), which was higher than that of wet-hot events (ER = 3.21%, 95% CI: 0.59%, 5.89%). The attributable fraction (AF) of mortality attributed to dry-hot events was 10.00% (95% CI: 9.50%, 10.72%) with higher burden for females, older people, central China, cardiovascular diseases and urban city. While for wet-hot events, AF was much lower (3.31%, 95% CI: 2.60%, 4.30%). We also found that high temperature and low relative humidity had synergistic additive interaction on mortality risk., Conclusion: Dry-hot events may have a higher risk of mortality than wet-hot events, and the joint effect of high temperature and low relative humidity may be greater than the sum of their individual effects., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Although studies have estimated the associations of PM 2.5 with total mortality or cardiopulmonary mortality, few have comprehensively examined cause-specific mortality risk and burden caused by ambient PM 2.5. Thus, this study investigated the association of short-term exposure to PM 2.5 with cause-specific mortality using a death-spectrum wide association study (DWAS). Individual information of 5,450,764 deaths during 2013–2018 were collected from six provinces in China. Daily PM 2.5 concentration in the case and control days were estimated by a random forest model. A time-stratified case-crossover study design was applied to estimate the associations (access risk, ER) of PM 2.5 with cause-specific mortality, which was then used to calculate the population-attributable fraction (PAF) of mortality and the corresponding mortality burden caused by PM 2.5. Each 10 μg/m3 increase in PM 2.5 concentration (lag03) was associated with a 0.80 % [95 % confidence interval (CI): 0.73 %, 0.86 %] rise in total mortality. We found greater mortality effect at PM 2.5 concentrations < 50 μg/m3. Stratified analyses showed greater ERs in females (1.01 %, 95 %CI: 0.91 %, 1.11 %), children ≤ 5 years (2.17 %, 95 %CI: 0.85 %, 3.51 %), and old people ≥ 70 years. We identified 33 specific causes (level 2) of death which had significant associations with PM 2.5 , including 16 circulatory diseases, 9 respiratory diseases, and 8 other causes. The PAF estimated based on the overall association between PM 2.5 and total mortality was 3.16 % (95 %CI: 2.89 %, 3.40 %). However, the PAF was reduced to 2.88 % (95 %CI: 1.88 %, 3.81 %) using the associations of PM 2.5 with 33 level 2 causes of death, based on which 250.15 (95 %CI: 163.29, 330.93) thousand deaths were attributable to short-term PM 2.5 exposure across China in 2019. Overall, this study provided a comprehensive picture on the death-spectrum wide association between PM 2.5 and morality in China. We observed robust positive cause-specific associations of PM 2.5 with mortality risk, which may provide more precise basis in assessing the mortality burden of air pollution. [Display omitted] • We estimate association of short-term exposure to PM 2.5 with cause-specific mortality. • A time-stratified case-crossover study design was used in 5.4 million deaths in China. • Short-term exposure to PM 2.5 is associated with mortality from 33 specific causes. • Mortality burden of PM 2.5 using associations with total mortality was overestimated. • The results provide more precise basis in assessing mortality burden of air pollution. [ABSTRACT FROM AUTHOR]

The short-term effects of ambient temperature on mortality have been widely investigated. However, the epidemiological evidence on the long-term effects of temperature on mortality is rare. In present study, we conducted a nationwide quasi-experimental design, which based on a variant of difference-in-differences (DID) approach, to examine the association between long-term exposure to ambient temperature and mortality risk in China, and to analyze the effect modification of population characteristics and socioeconomic status. Data on mortality were collected from 364 communities across China during 2006–2017, and environmental data were obtained for the same period. We estimated a 2.93 % (95 % CI: 2.68 %, 3.18 %) increase in mortality risk per 1 °C decreases in annual temperature, the greater effects were observed on respiratory diseases (5.16 %, 95 % CI: 4.53 %, 5.79 %) than cardiovascular diseases (3.43 %, 95 % CI: 3.06 %, 3.80 %), and on younger people (4.21 %, 95 % CI: 3.73 %, 4.68 %) than the elderly (2.36 %, 95 % CI: 2.06 %, 2.65 %). In seasonal analysis, per 1 °C decreases in average temperature was associated with 1.55 % (95 % CI: 1.23 %, 1.87 %), −0.53 % (95 % CI: −0.89 %, −0.16 %), 2.88 % (95 % CI: 2.45 %, 3.31 %) and 4.21 % (95 % CI: 3.98 %, 4.43 %) mortality change in spring, summer, autumn and winter, respectively. The effects of long-term temperature on total mortality were more pronounced among the communities with low urbanization, low education attainment, and low GDP per capita. In total, the decrease of average temperature in summer decreased mortality risk, while increased mortality risk in other seasons, and the associations were modified by demographic characteristics and socioeconomic status. Our findings suggest that populations with disadvantaged characteristics and socioeconomic status are vulnerable to long-term exposure of temperature, and targeted policies should be formulated to strengthen the response to the health threats of temperature exposure. [Display omitted] • Long-term effect of temperature on health was assessed by a quasi-experiment study. • The decreased summer temperature was associated with decreased mortality risks. • The average winter temperature is negatively correlated with mortality risks. • People with respiratory diseases and the young are more susceptible to temperature. • The temperature risk are more prominent in areas with low socioeconomic status. [ABSTRACT FROM AUTHOR]

The association between temperature and mortality has been widely investigated, however, studies on the effects of central heating on mortality risk are sparse. We applied a variant of difference-in-differences (DID) approach to assess the effects of central heating on winter mortality in China, and further analyzed the modification effect of central heating on the temperature-mortality association. Central heating was negatively associated with winter mortality (OR: 0.42, 95% CI: 0.39, 0.46) with higher effects on females and the elderly. Compared with cardiovascular or cerebrovascular diseases, central heating had a much greater effect on respiratory diseases. Every week less in central heating duration was associated with a 3.32% (95% CI: 3.03%, 3.61%) increased risk in total mortality. We found the temperature effect was much more pronounced among the locations without central heating (ER: 5.01%, 95% CI: 4.68%, 5.34%) than those with central heating (ER: 0.01%, 95% CI: −0.74%, 0.75%). The analysis suggests that central heating significantly decreases winter mortality in northern China, which may partly be achieved by attenuating the mortality caused by temperature. Therefore, central heating should be developed in some regions of southern China to reduce the mortality risk of low temperature in winter. • Central heating reduces the winter mortality risk in northern China by nearly 60%. • Per week less in heating duration was related to a 3.3% increased mortality risk. • Central heating improves people's adaptability to low temperatures. [ABSTRACT FROM AUTHOR]