A multi-country analysis on potential adaptive mechanisms to cold and heat in a changing climate

The differential effect of ambient temperature on age-specific and sex-specific mortality in the 300 largest cities of Russia, 2000-19: a first national time-series study

BACKGROUND

Despite a substantial body of evidence on the association between ambient temperature and mortality worldwide, there has not yet been a comprehensive country-wide assessment of the health effects of temperature in Russia. Moreover, there is no consensus on the effect of non-optimal temperatures on age-specific and sex-specific mortality. Our study aimed to provide the first analysis of temperature-related mortality in a large assembly of cities located in different geographical and socioeconomic zones of Russia.

METHODS

We analysed 19 044 538 non-accidental deaths in the 300 most populated cities in Russia between 2000 and 2019. A two-stage analysis strategy was used. First, a quasi-Poisson time-series model with distributed lag non-linear model was fitted to estimate city-specific associations. Second, these associations were pooled with multivariate multilevel meta-regression, from which we also calculated temperature-attributable mortality.

FINDINGS

Relative risks were generally higher for cold than for heat, except for cities in southern European Russia. Cold had a similar effect in both sexes, with a varying age gradient across cities. Although the effect of heat was generally stronger in women than in men, with the relative risk increasing steadily with age in both sexes, men younger than 60 years had a significantly higher risk of dying from heat than women of the same age. With a total of 106 007 (95% empirical CI [eCI]: 88 942-121 318) temperature-attributable deaths, there was a higher mortality attributable fraction for cold (10·74%, 95% eCI 8·80-11·99) than for heat (0·67%, 0·42-0·88).

INTERPRETATION

Russia has a high temperature-related mortality burden, with large differences in risk between cities and subpopulations. This information should be taken into account when planning public health interventions.

FUNDING

European Research Council, National Health and Medical Research Council, and Australian Research Council.

Regional changes in temperature-related mortality before and during the COVID-19 pandemic: a continental modelling analysis in 805 European regions

BACKGROUND

The COVID-19 pandemic drastically disrupted usual seasonal mortality patterns, creating challenges in assessing temperature-related mortality. While previous studies explored the effect of temperature on SARS-CoV-2 transmission, few examined its relationship with mortality during the pandemic, often excluding COVID-19 deaths or relying on pre-pandemic models. In this study, we developed an innovative methodological framework that accounts for COVID-19 waves, allowing us to estimate changes in the short-term effects of temperature on mortality and assess the role of adaptation and maladaptation before and after the onset of the pandemic.

METHODS

We analyzed pre- (2015-2019) and pandemic (2020-2023) mortality data from Eurostat, covering 805 contiguous regions across 32 European countries. To adjust for COVID-19 deaths, we selected specific time windows during COVID-19 waves, and increased the degrees of freedom (d.f.) for these windows as necessary until achieving well-behaved residuals.

FINDINGS

Adjusting for COVID-19 deaths reduced uncertainty in the pandemic association, providing more precise estimates. When adjusting for COVID-19 deaths, we observed a significant reduction in cold and heat-related mortality risks in all sub-regions except in the southern regions for heat, which experienced a significant increase. When assessing the role of adaptation between pre- and pandemic periods, we observed significant changes for heat risks in southern and western regions with higher risks in the pandemic period than in the pre-pandemic one. For cold, all sub-regions except the southern ones had higher risks in the pre-pandemic period.

INTERPRETATION

Our work defines a new innovative methodological framework for future epidemiological studies using data from the pandemic period. The proposed methodology demonstrates the importance of using pandemic data and adjusting for COVID-19 deaths to accurately capture current vulnerabilities. The findings highlight different regional adaptation processes and underscore the need for enhanced heat adaptation measures, particularly in vulnerable regions.

Estimating future heat-related and cold-related mortality under climate change, demographic and adaptation scenarios in 854 European cities

Previous health impact assessments of temperature-related mortality in Europe indicated that the mortality burden attributable to cold is much larger than for heat. Questions remain as to whether climate change can result in a net decrease in temperature-related mortality. In this study, we estimated how climate change could affect future heat-related and cold-related mortality in 854 European urban areas, under several climate, demographic and adaptation scenarios. We showed that, with no adaptation to heat, the increase in heat-related deaths consistently exceeds any decrease in cold-related deaths across all considered scenarios in Europe. Under the lowest mitigation and adaptation scenario (SSP3-7.0), we estimate a net death burden due to climate change increasing by 49.9% and cumulating 2,345,410 (95% confidence interval = 327,603 to 4,775,853) climate change-related deaths between 2015 and 2099. This net effect would remain positive even under high adaptation scenarios, whereby a risk attenuation of 50% is still insufficient to reverse the trend under SSP3-7.0. Regional differences suggest a slight net decrease of death rates in Northern European countries but high vulnerability of the Mediterranean region and Eastern Europe areas. Unless strong mitigation and adaptation measures are implemented, most European cities should experience an increase of their temperature-related mortality burden.

Association between ambient temperature and years of life lost of external causes of death in 16 prefecture-level regions of Yunnan Province

BACKGROUND

Many injury deaths are related to the environment. This study examined the impact of ambient temperature on external causes of death in Yunnan Province.

METHODS

Data on external causes of death and meteorological information were collected from 2014 to 2020 across 129 counties and districts of Yunnan Province. We estimated associations of the years of life lost (YLL) and its attributable fraction (AF) with temperature using a distributed lag non-linear model in each city and then pooled them in a multivariate meta-regression.

RESULTS

This study included 191 115 external causes of death and daily YLL was 2338.1 years. The relationship between mean temperature and YLL was found to be U-shaped. The AF of the YLL was 12.65% (95% empirical CI (eCI) 7.80% to 16.45%), 18.54% (95% eCI 8.91% to 23.56%) and 15.79% (95% eCI 8.83% to 20.07%) for external causes of death, traffic accidents and other external causes, respectively. Most of the disease burden was attributed to heat temperature. In the disease burden caused by temperature, males, individuals under 75 years old and those of Han ethnicity were mainly affected by heat temperature; individuals over 75 years old and minority populations were mainly affected by cold temperatures. Non-farmers are more affected by temperature than farmers.

CONCLUSIONS

The findings suggest that ambient temperature impacts external causes of death, and the results vary by gender, age, ethnicity and occupation. The study shows the importance of implementing preventive measures targeting both the general population and vulnerable groups in order to address external causes of death in future adaptation policies.

Toward a Cohort Perspective of Climate Epidemiology: The Case of Examining Intergenerational Inequalities in Susceptibility to Non-Optimal Temperatures in Japan

BACKGROUND

Younger generations are projected to experience more severe climate exposure impacts during their lifetimes than older generations as global warming progresses. Despite the increasing evidence of the recent temporal changes in heat-related mortality risks, there remains a lack of research exploring this association from a cohort perspective.

OBJECTIVE

Our objective was to quantify the variation in susceptibility to short-term effects of non-optimal temperature on mortality, across generations and over the life course of specific generations, using a novel age-period-cohort approach.

METHODS

An extended two-stage analytical approach was applied to a nationwide mortality dataset covering individuals born from 1866 to 2019 in all 47 prefectures in Japan. Daily mortality counts observed between 1972 and 2019 were aggregated into 5-year birth cohorts and corresponding age groups of the decedents. For each prefecture and birth cohort, the age-dependent association between ambient temperature and daily mortality was modeled using conditional quasi-Poisson regression. Then, the prefecture-specific associations were pooled across cohorts, separately for each age group, using a repeated-measure meta-regression. To model the intergenerational changes in risks, a nonlinear, continuous term for cohort was applied in the meta-analysis.

RESULTS

A total of 29 million all-cause deaths were analyzed. The relative risk (RR) of heat-related mortality (99th temperature percentile compared to minimum mortality temperature) decreased across generations for elder adults (65-89 years of age), from RR = 1.18 [95% confidence interval (CI): 1.13, 1.23] for those born in 1901-1905 to RR = 1.04 (95% CI: 1.01, 1.07) for those born in 1926-1930 (p -trend = 0.004 ). Similar to heat-related risk, the cold-related mortality risk (at first percentile) also decreased across the same cohorts (p -trend < 0.001 ). The predicted continuous trends in heat- and cold-related mortality risks exhibited a nonlinear decline across generations. An inconsistent pattern was observed for middle-aged people (40-64 years of age) born between 1930 and 1960, with a slight increase in risks for cold and heat over generations. For cohort-specific risk trajectories, heat- and cold-related mortality risks generally increased with age, after 60 years old.

DISCUSSION

This nationwide, individual-level study adopted a novel cohort perspective to investigate how population susceptibility to short-term non-optimal temperature exposure varies across generations. Our findings revealed disparities in susceptibility between generations, highlighting the importance for researchers and policymakers to consider cohort differences in efforts to promote future health advancements and reduce inequalities. https://doi.org/10.1289/EHP15226.

The temporal change of heat exposure and adaptation capacity in Chinese adults from 1994 to 2023

Background

Studies have found decreased heat effect and increased minimum mortality temperature (MMT) during the past decades. However, it is unclear whether heat exposure or temperature adaptation play an important role in this change.

Methods

This is a cross-sectional study. Data were collected from 3,094 respondents aged 31-64 years old based on online questionnaire. The Cochran-Armitage test for trend and Cochran-Mantel-Haenszel (CMH) test were used for the difference between three decades. The Chi square test was employed to compare the difference between different demographic subgroups during 2014-2023. Multivariate logistic regression model was used to analyze the risk factors of air conditioner ownership.

Results

Most respondents (94.6%) thought ambient temperature had been increasing, and 57.0% people thought climate change impacted their health. Long duration outdoors work (≥4 h) decreased from 36.01, 30.93 to 24.53% (Z = -9.80, p < 0.01) and bicycling/walking decreased from 62.3, 27.9, to 9.7% (CMH value = 156.40, p < 0.01) significantly during the last three decades. Temperature adaptation capacity increased with air conditioner ownership rates increasing from 25.40, 57.63 to 81.51% at home (Z = -44.35, p < 0.01) and from 22.24, 57.47 to 80.51% in the office/school (Z = -45.95, p < 0.01), and the older adult, women, people with low income, outdoor work, low education, and people from northern China had lower air conditioner ownership rates. The frequency of air conditioner usage when felt hot also escalated significantly both at home (from 42.6%, 54.9, to 63.4%, CMH value = 156.40, p < 0.0001) and in the office/school (from 61.8, 63.1 to 72.7%, CMH value = 65.29, p < 0.0001) during the same periods.

Conclusion

Our study found that most people perceived climate change and changed behaviors to adapt to heat. Heat exposure significantly decreased and temperature adaptation capacity significantly increased during the last decades. The findings implied that heat-related health risk and burden driven by global warming may not increase in the future.

The reciprocal relation between rising longevity and temperature-related mortality risk in older people, Spain 1980-2018

Temperature-related mortality mostly affects older people and is attributable to a combination of factors. We focussed on a key non-temperature factor - rising longevity - and aimed to quantify its reciprocal relation with temperature-related mortality risk in Spain over 1980-2018. We obtained average annual temperature-attributable deaths among people aged 65y+, by sex and age group, for different temperature ranges (extreme cold, moderate cold, moderate heat, and extreme heat), from a previous study. Combining this with population and mortality data as well as life table information, we used: (i) a counterfactual approach to assess the contribution of rising longevity to changes in the absolute risk of temperature-related mortality, and (ii) decomposition to assess the contribution of changes in temperature-related mortality to changes in longevity and its variation (lifespan inequality). Rising longevity led to considerable declines in the absolute risk of temperature-related mortality in females and males across the entire temperature range. For extreme heat, it accounted for about a 30% decrease in absolute risk (half of the total decrease over the study period). For moderate and extreme cold, it accounted for about a 20% fall in absolute risk (a quarter of the total fall). In the opposite direction, changing patterns of temperature-related deaths contributed to higher life expectancy (accounting for > 20% of the total rise in both females and males) but also higher lifespan inequality amongst older people. Most of the influence (about 80%) was via moderate cold, but declines in risk at both moderate and extreme heat led to small rises in life expectancy. Our study points to the benefits of adopting risk-reduction strategies that aim, not only at modifying hazards and reducing exposure, but that also address socially-generated vulnerability among older people. This includes ensuring that lifespans lengthen primarily through increases in years lived in good health.

Heat-related mortality in Europe during 2023 and the role of adaptation in protecting health

The year of 2023 was the warmest on record globally and the second warmest in Europe. Here we applied epidemiological models to temperature and mortality records in 823 contiguous regions from 35 countries to estimate sex- and age-specific heat-related mortality in Europe during 2023 and to quantify the mortality burden avoided by societal adaptation to rising temperatures since the year 2000. We estimated 47,690 (95% confidence interval 28,853 to 66,525) heat-related deaths in 2023, the second highest mortality burden during the study period 2015-2023, only surpassed by 2022. We also estimated that the heat-related mortality burden would have been +80.0% higher in absence of present-century adaptation, especially in the elderly (+100.7% in people aged 80+ years). Our results highlight the importance of historical and ongoing adaptations in saving lives during recent summers and the urgency for more effective strategies to further reduce the mortality burden of forthcoming hotter summers.

Planetary boundaries transgressions: A review on the implications to public health

This literature review systematically examines the impacts of violating planetary boundaries from 2009 to 2023, emphasizing the implications for human health. Planetary boundaries define safe operational limits for Earth's systems, and their transgression poses significant threats to environmental stability and public health. This paper reviews extensive research on the health effects of breaches in these boundaries, including climate change, biodiversity loss, freshwater use, and aerosol loading. The review integrates findings from numerous studies, providing a critical overview of health impacts across various global regions. The analysis underscores the intricate links between planetary boundaries breaching impacts, highlighting urgent policy and governance challenges. The study's outcomes aim to inform policymakers, businesses, and communities, promoting sustainable development and resilience in the face of escalating global challenges.

Temporal change in minimum mortality temperature under changing climate: A multicountry multicommunity observational study spanning 1986-2015

Background

The minimum mortality temperature (MMT) or MMT percentile (MMTP) is an indicator of population susceptibility to nonoptimum temperatures. MMT and MMTP change over time; however, the changing directions show region-wide heterogeneity. We examined the heterogeneity of temporal changes in MMT and MMTP across multiple communities and in multiple countries.

Methods

Daily time-series data for mortality and ambient mean temperature for 699 communities in 34 countries spanning 1986-2015 were analyzed using a two-stage meta-analysis. First, a quasi-Poisson regression was employed to estimate MMT and MMTP for each community during the designated subperiods. Second, we pooled the community-specific temporally varying estimates using mixed-effects meta-regressions to examine temporal changes in MMT and MMTP in the entire study population, as well as by climate zone, geographical region, and country.

Results

Temporal increases in MMT and MMTP from 19.5 °C (17.9, 21.1) to 20.3 °C (18.5, 22.0) and from the 74.5 (68.3, 80.6) to 75.0 (71.0, 78.9) percentiles in the entire population were found, respectively. Temporal change was significantly heterogeneous across geographical regions (P < 0.001). Temporal increases in MMT were observed in East Asia (linear slope [LS] = 0.91, P = 0.02) and South-East Asia (LS = 0.62, P = 0.05), whereas a temporal decrease in MMT was observed in South Europe (LS = -0.46, P = 0.05). MMTP decreased temporally in North Europe (LS = -3.45, P = 0.02) and South Europe (LS = -2.86, P = 0.05).

Conclusions

The temporal change in MMT or MMTP was largely heterogeneous. Population susceptibility in terms of optimum temperature may have changed under a warming climate, albeit with large region-dependent variations.

Temperature-mortality associations by age and cause: a multi-country multi-city study

Background

Heterogeneity in temperature-mortality relationships across locations may partly result from differences in the demographic structure of populations and their cause-specific vulnerabilities. Here we conduct the largest epidemiological study to date on the association between ambient temperature and mortality by age and cause using data from 532 cities in 33 countries.

Methods

We collected daily temperature and mortality data from each country. Mortality data was provided as daily death counts within age groups from all, cardiovascular, respiratory, or noncardiorespiratory causes. We first fit quasi-Poisson regression models to estimate location-specific associations for each age-by-cause group. For each cause, we then pooled location-specific results in a dose-response multivariate meta-regression model that enabled us to estimate overall temperature-mortality curves at any age. The age analysis was limited to adults.

Results

We observed high temperature effects on mortality from both cardiovascular and respiratory causes compared to noncardiorespiratory causes, with the highest cold-related risks from cardiovascular causes and the highest heat-related risks from respiratory causes. Risks generally increased with age, a pattern most consistent for cold and for nonrespiratory causes. For every cause group, risks at both temperature extremes were strongest at the oldest age (age 85 years). Excess mortality fractions were highest for cold at the oldest ages.

Conclusions

There is a differential pattern of risk associated with heat and cold by cause and age; cardiorespiratory causes show stronger effects than noncardiorespiratory causes, and older adults have higher risks than younger adults.

The Multi-Country Multi-City Collaborative Research Network: An international research consortium investigating environment, climate, and health

Research on the health risks of environmental factors and climate change requires epidemiological evidence on associated health risks at a global scale. Multi-center studies offer an excellent framework for this purpose, but they present various methodological and logistical problems. This contribution illustrates the experience of the Multi-Country Multi-City Collaborative Research Network, an international collaboration working on a global research program on the associations between environmental stressors, climate, and health in a multi-center setting. The article illustrates the collaborative scheme based on mutual contribution and data and method sharing, describes the collection of a huge multi-location database, summarizes published research findings and future plans, and discusses advantages and limitations. The Multi-Country Multi-City represents an example of a collaborative research framework that has greatly contributed to advance knowledge on the health impacts of climate change and other environmental factors and can be replicated to address other research questions across various research fields.

Unbiased temperature-related mortality estimates using weekly and monthly health data: a new method for environmental epidemiology and climate impact studies

BACKGROUND

Exposure to environmental factors has a high burden on human health, with millions of premature annual deaths associated with the short-term health effects of ambient temperatures and air pollution. However, direct estimations of exposure-related mortality from real data are still not available in most parts of the world, especially in low-resource settings, due to the unavailability of daily health records to calibrate epidemiological models.

METHODS

In this study, we have filled the crucial gap in available direct estimations by developing a method to make valid inference for the relationship between exposure and response data that uses only exposure and temporally aggregated response data. We provided the mathematical derivation of the method, and compared the results by using simulations applied to daily temperature and daily, weekly, and monthly mortality data. The method was then applied to the newly created database of the EARLY-ADAPT project.

FINDINGS

The daily and weekly models produced similar and unbiased estimates of the temperature-related relative risks and attributable mortality, with only slightly more imprecision in the weekly model. Even the estimates of the monthly model were unbiased when using enough data, although at the expense of a substantial increase in variability. The real data analysis showed that the similarity between the regional values of two aggregation models increased with the number of years and regions of the dataset, and decreased with the difference in their degree of temporal aggregation.

INTERPRETATION

Our method opens the door to conducting epidemiological studies in low-resource settings, where access to daily health data is not possible. Moreover, it allows accurate estimation of the short-term health effects of environmental exposures in near-real time, when daily health data are still not available, such as in the estimation of the mortality burden of recent record-breaking heat episodes. Overall, our method represents an important new approach to how the public health community can use data to create new evidence for research, translation and policy making.

FUNDING

European Research Council (ERC).

Thermal Comfort Conditions and Mortality in Brazil

Conventional temperature-based approaches often overlook the intricate nature of thermal stress experienced by individuals. To address this limitation, climatologists have developed thermal indices-composite measures designed to reflect the complex interaction of meteorological factors influencing human perception of temperature. Our study focuses on Brazil, estimating the association between thermal comfort conditions and mortality related to respiratory and circulatory diseases. We examined four distinct thermal indices: the discomfort index (DI), net effective temperature (NET), humidex (H), and heat index (HI). Analyzing a comprehensive dataset of 2,872,084 deaths from 2003 to 2017, we found significant variation in relative risk (RR) based on health outcomes, exposure lag, percentile of exposure, sex/age groups, and specific thermal indices. For example, under high exposure conditions (99th percentile), we observed that the shorter lags (3, 5, 7, and 10) had the most robust effects on all-cause mortality. For example, under lag 3, the pooled national results for the overall population (all ages and sexes) indicate an increased risk of all-cause mortality, with an RR of 1.17 (95% CI: 1.13; 1.122) for DI, 1.15 (95% CI: 1.12; 1.17) for H, 1.15 (95% CI: 1.09; 1.21) for HI, and 1.18 (95% CI: 1.13; 1.22) for NET. At low exposure levels (1st percentile), all four distinct thermal indices were linked to an increase in all-cause mortality across most sex and age subgroups. Specifically, for lag 20, we observed an estimated RR of 1.19 (95% CI: 1.14; 1.23) for DI, 1.12 (95% CI: 1.08; 1.16) for H, 1.17 (95% CI: 1.12; 1.22) for HI, and 1.18 (95% CI: 1.14; 1.23) for NET. These findings have important implications for policymakers, guiding the development of measures to minimize climate change's impact on public health in Brazil.

The temporal variation in the effects of extreme temperature on respiratory mortality: Evidence from 136 cities in China, 2006-2019

BACKGROUND

In the context of climate change and urbanization, the temporal variation of the adverse health effect of extreme temperature has attracted increasing attention.

METHODS

The meteorological data and the daily death records of mortality from respiratory diseases of 136 Chinese cities were from 2006 to 2019. Heat wave and cold spell were selected as the indicator events of extreme high temperature and extreme low temperature, respectively. The generalized linear model and time-varying distributed lag model were used to perform a two-stage time-series analysis to evaluate the temporal variation of the mortality risk associated with extreme temperature in the total population, sub-populations (sex- and age- specific) and different regions (climatic zone and relative humidity level).

RESULTS

During the study period, relative risk (RR) of respiratory mortality associated with heat wave decreased from 1.22 (95 %CI: 1.07-1.39) to 1.13 (95 %CI: 1.01-1.26) in the total population, and RR of respiratory mortality associated with cold spell decreased from 1.30 (95 %CI: 1.14-1.49) to 1.17 (95 %CI: 1.08-1.26). The impact of heat wave reduced in the males (P = 0.044) and in the females as with cold spell (P < 0.001). The respiratory mortality risk of people over 65 associated with cold spell decreased (P = 0.040 for people aged 65-74 and P < 0.001 for people over 75). The effect of cold spell reduced in cities from tropical or arid zone (P = 0.035). The effects of both heat wave and cold spell decreased in cities with the relative humidity in the first quartile (P = 0.046 and 0.010, respectively).

CONCLUSION

The impact of heat wave on mortality of respiratory diseases decreased mainly in males and cities with the lowest relative humidity, while the impact of cold spell reduced in females, people over 65 and tropical and arid zone, suggesting adaptation to extreme temperature of Chinese residents to some extent.

Global climate change: Effects of future temperatures on emergency department visits for mental disorders in Beijing, China

Rising temperatures can increase the risk of mental disorders. As climate change intensifies, the future disease burden due to mental disorders may be underestimated. Using data on the number of daily emergency department visits for mental disorders at 30 hospitals in Beijing, China during 2016-2018, the relationship between daily mean temperature and such visits was assessed using a quasi-Poisson model integrated with a distributed lag nonlinear model. Emergency department visits for mental disorders attributed to temperature changes were projected using 26 general circulation models under four climate change scenarios. Stratification analyses were then conducted by disease subtype, sex, and age. The results indicate that the temperature-related health burden from mental disorders was projected to increase consistently throughout the 21st century, mainly driven by high temperatures. The future temperature-related health burden was higher for patients with mental disorders due to the use of psychoactive substances and schizophrenia as well as for women and those aged <65 years. These findings enhance our knowledge of how climate change could affect mental well-being and can be used to advance and refine targeted approaches to mitigating and adapting to climate change with a view on addressing mental disorders.

Impacts of heatwaves on type 2 diabetes mortality in China: a comparative analysis between coastal and inland cities

The impacts of extreme temperatures on diabetes have been explored in previous studies. However, it is unknown whether the impacts of heatwaves appear variations between inland and coastal regions. This study aims to quantify the associations between heat exposure and type 2 diabetes mellitus (T2DM) deaths in two cities with different climate features in Shandong Province, China. We used a case-crossover design by quasi-Poisson generalized additive regression with a distributed lag model with lag 2 weeks, controlling for relative humidity, the concentration of air pollution particles with a diameter of 2.5 µm or less (PM2.5), and seasonality. The wet- bulb temperature (Tw) was used to measure the heat stress of the heatwaves. A significant association between heatwaves and T2DM deaths was only found in the coastal city (Qingdao) at the lag of 2 weeks at the lowest Tw = 14℃ (relative risk (RR) = 1.49, 95% confidence interval (CI): 1.11-2.02; women: RR = 1.51, 95% CI: 1.02-2.24; elderly: RR = 1.50, 95% CI: 1.08-2.09). The lag-specific effects were significant associated with Tw at lag of 1 week at the lowest Tw = 14℃ (RR = 1.14, 95% CI: 1.03-1.26; women: RR = 1.15, 95% CI: 1.01-1.31; elderly: RR = 1.15, 95% CI: 1.03-1.28). However, no significant association was found in Jian city. The research suggested that Tw was significantly associated with T2DM mortality in the coastal city during heatwaves on T2DM mortality. Future strategies should be implemented with considering socio-environmental contexts in regions.

Remeasuring the influence of ageing on heat-related mortality in Spain, 1980 to 2018

Climate change and population ageing are converging challenges that are expected to significantly worsen the health impacts of high temperatures. We aimed to remeasure the implications of ageing for heat-related mortality by comparing time trends based on chronological age (number of years already lived) with those derived from the application of state-of-the-art demographic methodology which better captures the dynamics of evolving longevity: prospective age (number of years still to be lived). We conducted a nationwide time-series analysis of 13 regions in Spain over 1980-2018 using all-cause mortality microdata for people aged 65+ and annual life tables from the Spanish National Institute of Statistics, and daily mean temperatures from E-OBS. Based on confounder-adjusted quasi-Poisson regression with distributed lag non-linear models and multivariate meta-analysis in moving 15-year timeslices, we assessed sex-specific changes in absolute risk and impacts for heat-related mortality at extreme and moderate temperatures, for chronological and prospective age groups. In the conventional chronological age analysis, absolute risk fell over the study period (e.g. females, extreme heat: -54%; moderate heat: -23%); after accounting for rising longevity, the prospective age analysis, however, found a smaller decline in risk for extreme heat (-15%) and a rise for moderate heat (+46%). Additionally, while the chronological age analysis suggested a shift in mortality towards higher ages, the prospective age analysis showed that over the study period, people of largely the same (prospective) age were impacted. Further, the prospective age analysis revealed excess risk in females (compared to males) rose from 20% to 27% for extreme heat, and from 40% to 70% for moderate heat. Assessing the implications of ageing using a prospective age perspective showed the urgency of re-doubling risk reduction efforts, including accelerating healthy ageing programs that incorporate climate considerations. The age patterns of impacts suggested that such actions have the potential to mitigate ageing-related heat-health threats to generate climate change-ready, healthy societies.

Temperature frequency and mortality: Assessing adaptation to local temperature

Assessing the association between temperature frequency and mortality can provide insights into human adaptation to local ambient temperatures. We collected daily time-series data on mortality and temperature from 757 locations in 47 countries/regions during 1979-2020. We used a two-stage time series design to assess the association between temperature frequency and all-cause mortality. The results were pooled at the national, regional, and global levels. We observed a consistent decrease in the risk of mortality as the normalized frequency of temperature increases across the globe. The average increase in mortality risk comparing the 10th to 100th percentile of normalized frequency was 13.03% (95% CI: 12.17-13.91), with substantial regional differences (from 4.56% in Australia and New Zealand to 33.06% in South Europe). The highest increase in mortality was observed for high-income countries (13.58%, 95% CI: 12.56-14.61), followed by lower-middle-income countries (12.34%, 95% CI: 9.27-15.51). This study observed a declining risk of mortality associated with higher temperature frequency. Our findings suggest that populations can adapt to their local climate with frequent exposure, with the adapting ability varying geographically due to differences in climatic and socioeconomic characteristics.

Rising trend and regional disparities of the global burden of disease attributable to ambient low temperature, 1990-2019: An analysis of data from the Global Burden of Disease 2019 study

Background

Previous studies on the effect of global warming on the global burden of disease have mainly focussed on the impact of high temperatures, thereby providing limited evidence of the effect of lower temperatures.

Methods

We adopted a three-stage analysis approach using data from the Global Burden of Disease 2019 study. First, we explored the global burden of disease attributable to low temperatures, examining variations by gender, age, cause, region, and country. Second, we analysed temporal trends in low-temperature-related disease burdens from 1990 to 2019 by meta-regression. Finally, we fitted a mixed-effects meta-regression model to explore the effect modification of country-level characteristics.

Results

In 2019, low temperatures were responsible for 2.92% of global deaths and 1.03% of disability-adjusted life years (DALYs), corresponding to a death rate of 21.36 (95% uncertainty interval (UI) = 18.26, 24.73) and a DALY rate of 335 (95% UI = 280, 399) per 100 000 population. Most of the deaths (85.12%) and DALYs (94.38%) attributable to low temperatures were associated with ischaemic heart disease, stroke, and chronic obstructive pulmonary disease. In the last three decades, we observed an upward trend for the annual number of attributable deaths (P < 0.001) and a downward trend for the rates of death (P < 0.001) and DALYs (P < 0.001). The disease burden associated with low temperatures varied considerably among regions and countries, with higher burdens observed in regions with middle or high-middle socio-demographic indices, as well as countries with higher gross domestic product per capita and a larger proportion of ageing population.

Conclusions

Our findings emphasise the significance of raising public awareness and prioritising policies to protect global population health from the adverse effects of low temperatures, even in the face of global warming. Particular efforts should be targeted towards individuals with underlying diseases (e.g. cardiovascular diseases) and vulnerable countries or regions (e.g. Central Asia and central Europe).

Projection of Mortality Burden Attributable to Nonoptimum Temperature with High Spatial Resolution in China

The updated climate models provide projections at a fine scale, allowing us to estimate health risks due to future warming after accounting for spatial heterogeneity. Here, we utilized an ensemble of high-resolution (25 km) climate simulations and nationwide mortality data from 306 Chinese cities to estimate death anomalies attributable to future warming. Historical estimation (1986-2014) reveals that about 15.5% [95% empirical confidence interval (eCI):13.1%, 17.6%] of deaths are attributable to nonoptimal temperature, of which heat and cold corresponded to attributable fractions of 4.1% (eCI:2.4%, 5.5%) and 11.4% (eCI:10.7%, 12.1%), respectively. Under three climate scenarios (SSP126, SSP245, and SSP585), the national average temperature was projected to increase by 1.45, 2.57, and 4.98 °C by the 2090s, respectively. The corresponding mortality fractions attributable to heat would be 6.5% (eCI:5.2%, 7.7%), 7.9% (eCI:6.3%, 9.4%), and 11.4% (eCI:9.2%, 13.3%). More than half of the attributable deaths due to future warming would occur in north China and cardiovascular mortality would increase more drastically than respiratory mortality. Our study shows that the increased heat-attributable mortality burden would outweigh the decreased cold-attributable burden even under a moderate climate change scenario across China. The results are helpful for national or local policymakers to better address the challenges of future warming.

Impact of population aging on future temperature-related mortality at different global warming levels

Older adults are generally amongst the most vulnerable to heat and cold. While temperature-related health impacts are projected to increase with global warming, the influence of population aging on these trends remains unclear. Here we show that at 1.5 °C, 2 °C, and 3 °C of global warming, heat-related mortality in 800 locations across 50 countries/areas will increase by 0.5%, 1.0%, and 2.5%, respectively; among which 1 in 5 to 1 in 4 heat-related deaths can be attributed to population aging. Despite a projected decrease in cold-related mortality due to progressive warming alone, population aging will mostly counteract this trend, leading to a net increase in cold-related mortality by 0.1%-0.4% at 1.5-3 °C global warming. Our findings indicate that population aging constitutes a crucial driver for future heat- and cold-related deaths, with increasing mortality burden for both heat and cold due to the aging population.

Associations between cold spells of different time types and coronary heart disease severity

Limited evidence showed the association between cold spells and the severity of coronary heart disease (CHD). This study was to investigate the association between cold spells with their different time types and CHD severity. We collected data on CHD patients admitted to the Zhongnan Hospital, Wuhan, China from 2016 to 2021. CHD severity was quantified using the SYNTAX score and transformed into a binomial variable. Daily mean, maximum and minimum temperature were collected during the study period. We first used daily mean temperature to find the optimum definition among multiple thresholds and durations. The daily maximum and minimum temperatures were used to define different types of cold spells (daytime, nighttime and compound) based on the optimum definition. Annual cold spell days were included to assess individual exposure to cold spells. Logistic regression models were performed to fit the association between cold spell days and CHD severity stratified by different tertiles of PM2.5 and NDVI. In this study, 1937 CHD patients were included. The cold spell defined as at least four consecutive days with daily mean temperature below the 5th percentile exhibited the optimum model. We found that a 4-day increase in cold spell days was associated with more severe CHD (OR = 1.170, 95% CI: 1.074, 1.282). Such an association was more pronounced under higher levels of PM2.5 by OR = 1.270 (1.086, 1.494) and lower levels of greenness by OR = 1.240 (1.044, 1.476). Compared with daytime and compound cold spells, nighttime cold spells showed the strongest association with CHD severity by OR = 1.141 (1.026, 1.269). This study showed that exposure to cold spells was positively associated with CHD severity, especially the nighttime cold spells. The association between cold spells and CHD severity was more significant in high levels of PM2.5 and low levels of greenness.

Countrywide analysis of heat- and cold-related mortality trends in the Czech Republic: growing inequalities under recent climate warming

BACKGROUND

Only little is known about trends in temperature-mortality associations among the most vulnerable subgroups, especially in the areas of central and eastern Europe, which are considered major climatic hotspots in terms of heatwave exposure. Thus, we aimed to assess trends in temperature-related mortality in the Czech Republic by sex, age and cause of death, and to quantify the temporal evolution of possible inequalities.

METHODS

We collected daily time series of all-cause (1987-2019) and cause-specific (1994-2019) mortality by sex and age category, and population-weighted daily mean 2-metre temperatures for each region of the Czech Republic. We applied a quasi-Poisson regression model to estimate the trends in region-specific temperature-mortality associations, with distributed lag non-linear models and multivariate random-effects meta-analysis to derive average associations across the country. We then calculated mortality attributable to non-optimal temperatures and implemented the indicator of sex- and age-dependent inequalities.

RESULTS

We observed a similar risk of mortality due to cold temperatures for men and women. Conversely, for warm temperatures, a higher risk was observed for women. Results by age showed a clear pattern of increasing risk due to non-optimum temperatures with increasing age category. The relative risk (RR) related to cold was considerably attenuated in most of the studied subgroups during the study period, whereas an increase in the RR associated with heat was seen in the overall population, in women, in the age category 90+ years and with respect to respiratory causes. Moreover, underlying sex- and age-dependent inequalities experienced substantial growth.

CONCLUSIONS

Our findings suggest ongoing adaptation to cold temperatures. Mal/adaptation to hot temperatures occurred unequally among population subgroups and resulted in growing inequalities between the sexes and among age categories.

The effect of temporal data aggregation to assess the impact of changing temperatures in Europe: an epidemiological modelling study

Background

Daily time-series regression models are commonly used to estimate the lagged nonlinear relation between temperature and mortality. A major impediment to this type of analysis is the restricted access to daily health records. The use of weekly and monthly data represents a possible solution unexplored to date.

Methods

We temporally aggregated daily temperatures and mortality records from 147 contiguous regions in 16 European countries, representing their entire population of over 400 million people. We estimated temperature-lag-mortality relationships by using standard time-series quasi-Poisson regression models applied to daily data, and compared the results with those obtained with different degrees of temporal aggregation.

Findings

We observed progressively larger differences in the epidemiological estimates with the degree of temporal data aggregation. The daily data model estimated an annual cold and heat-related mortality of 290,104 (213,745-359,636) and 39,434 (30,782-47,084) deaths, respectively, and the weekly model underestimated these numbers by 8.56% and 21.56%. Importantly, differences were systematically smaller during extreme cold and heat periods, such as the summer of 2003, with an underestimation of only 4.62% in the weekly data model. We applied this framework to infer that the heat-related mortality burden during the year 2022 in Europe may have exceeded the 70,000 deaths.

Interpretation

The present work represents a first reference study validating the use of weekly time series as an approximation to the short-term effects of cold and heat on human mortality. This approach can be adopted to complement access-restricted data networks, and facilitate data access for research, translation and policy-making.

Funding

The study was supported by the ERC Consolidator Grant EARLY-ADAPT (https://www.early-adapt.eu/), and the ERC Proof-of-Concept Grants HHS-EWS and FORECAST-AIR.

The influence of humid heat on morbidity of megacity Shanghai in China

BACKGROUND

Increased attention has been paid to humid-heat extremes as they are projected to increase in both frequency and intensity. However, it remains unclear how compound extremes of heat and humidity affects morbidity when the climate is projected to continue warming in the future, in particular for a megacity with a large population.

METHODS

We chose the Wet-Bulb Globe Temperature (WBGT) index as the metric to characterize the humid-heat exposure. The historical associations between daily outpatient visits and daily mean WBGT was established using a Distributed Lag Non-linear Model (DLNM) during the warm season (June to September) from 2013 to 2015 in Shanghai, a prominent megacity of China. Future morbidity burden related to the combined effect of high temperature and humidity were projected under four greenhouse gases (GHGs) emission scenarios (SSP126, SSP245, SSP370 and SSP585).

RESULTS

The humid-heat weather was significantly associated with a higher risk of outpatient visits in Shanghai than the high-temperature conditions. Relative to the baseline period (2010-2019), the morbidity burden due to humid-heat weather was projected to increase 4.4 % (95 % confidence interval (CI): 1.1 %-10.1 %) even under the strict emission control scenario (SSP126) by 2100. Under the high-GHGs emission scenario (SSP585), this burden was projected to be 25.4 % (95 % CI: 15.8 %-38.4 %), which is 10.1 % (95 % CI: 6.5 %-15.8 %) more than that due to high-temperature weather. Our results also indicate that humid-hot nights could cause large morbidity risks under high-GHGs emission scenarios particularly in heat-sensible diseases such as the respiratory and cardiovascular disease by the end of this century.

CONCLUSIONS

Humid heat exposures significantly increased the all-cause morbidity risk in the megacity Shanghai, especially in humid-hot nights. Our findings suggest that the combined effect of elevated temperature and humidity is projected to have more substantial impact on health compared to high temperature alone in a warming climate.

Association between non-optimal temperature and cardiovascular hospitalization and its temporal variation at the intersection of disability

BACKGROUND

While previous research has identified populations susceptible to non-optimal temperatures, disability has been largely overlooked. Given the growing number of persons with disabilities (PwD) and their social and health disadvantages, understanding how disability intersects with temperature-related health effects is crucial. This study aimed to investigate the associations between non-optimal temperatures and cardiovascular disease (CVD) hospitalization and examine how these associations vary over time considering the existence of disability.

METHODS

We used the National Health Insurance Service-National Sample Cohort to investigate the association between non-optimal temperatures and CVD hospitalization in South Korea, 2002-2019. We obtained daily mean temperature from the Korea Meteorological Administration's automated synoptic observing system. We applied a space-time-stratified case-crossover design using a conditional quasi-Poisson regression with a distributed lag non-linear model, adjusting for relative humidity, wind speed, and public holidays. We examined temporal variations in temperature-CVD hospitalization associations using a time window approach. All analyses used the minimum hospitalization temperature (20.0 °C) as reference and were stratified by disability status.

RESULTS

The cumulative exposure-response curve in persons without disabilities showed a J-shape with a relative risk (RR) of 1.07 (95 % confidence interval [CI]: 0.99, 1.15) at extreme heat (99th percentile) and 1.09 (95 % CI: 0.97, 1.23) at extreme cold (1st percentile). The cumulative exposure-response curve in PwD showed an M-shape with the highest RR at chill (1.22 [95 % CI: 1.13, 1.32]) and moderate cold temperature (1.11 [95 % CI: 1.01, 1.21]), defined as the 30th and 5th percentiles, respectively. The impacts of heat and cold decreased over time for persons without disabilities but increased for PwD.

CONCLUSIONS

Our study found differential temperature-related impacts on CVD hospitalization based on disability status, and PwD were maladapted to heat and cold over time. This suggests the importance of considering disability when investigating temperature-related health disparity and adopting disability-inclusive adaptation strategies.

Summer heat waves and their mortality risk over a 14-year period in a western region of Iran

Compared to previous decade, impact of heat waves (HWs) on mortality in recent years needs to be discussed in Iran. We investigated temporal change in added impact of summer HWs on mortality in eight cities of Iran. The pooled length of HWs was compared between 2015-2022 and 2008-2014 using random and fixed-effects of meta-analysis regression model. The temporal change in impact of HWs was evaluated through interaction effect between crossbasis function of HW and year in a two-stage time varying model. In order to pool the reduced coefficients of each period, multivariate meta-regression model, including city-specific temperature and temperature range as heterogenicity factors, was used. In addition to relative risk (RR), attributable fraction (AF) of HW in the two periods was also estimated in each city. In the last years, the frequency of all HWs was higher and the weak HWs were significantly longer. The only significant RR was related to the lowest and low severe HWs which was observed in the second period. In terms of AF, compared to the strong HWs, all weak HWs caused a considerable excess mortality in all cities and second period. The subgroup analysis revealed that the significant impact in the second period was mainly related to females and elderlies. The increased risk and AF due to more frequent and longer HWs (weak HWs) in the last years highlights the need for mitigation strategies in the region. Because of uncertainty in the results of severe HWs, further elaborately investigation of the HWs is need.

A Nationwide Comparative Analysis of Temperature-Related Mortality and Morbidity in Japan

BACKGROUND

The impact of temperature on morbidity remains largely unknown. Moreover, extensive evidence indicates contrasting patterns between temperature-mortality and temperature-morbidity associations. A nationwide comparison of the impact of temperature on mortality and morbidity in more specific subgroups is necessary to strengthen understanding and help explore underlying mechanisms by identifying susceptible populations.

OBJECTIVE

We performed this study to quantify and compare the impact of temperature on mortality and morbidity in 47 prefectures in Japan.

METHODS

We applied a two-stage time-series design with distributed lag nonlinear models and mixed-effect multivariate meta-analysis to assess the association of temperature with mortality and morbidity by causes (all-cause, circulatory, and respiratory) at prefecture and country levels between 2015 and 2019. Subgroup analysis was conducted by sex, age, and regions.

RESULTS

The patterns and magnitudes of temperature impacts on morbidity and mortality differed. For all-cause outcomes, cold exhibited larger effects on mortality, and heat showed larger effects on morbidity. At specific temperature percentiles, cold (first percentile) was associated with a higher relative risk (RR) of mortality [1.45; 95% confidence interval (CI): 1.39, 1.52] than morbidity (1.33; 95% CI: 1.26, 1.40), as compared to the minimum mortality/morbidity temperature. Heat (99th percentile) was associated with a higher risk of morbidity (1.30; 95% CI: 1.28, 1.33) than mortality (1.04; 95% CI: 1.02, 1.06). For cause-specific diseases, mortality due to circulatory diseases was more susceptible to heat and cold than morbidity. However, for respiratory diseases, both cold and heat showed higher risks for morbidity than mortality. Subgroup analyses suggested varied associations depending on specific outcomes.

DISCUSSION

Distinct patterns were observed for the association of temperature with mortality and morbidity, underlying different mechanisms of temperature on different end points, and the differences in population susceptibility are possible explanations. Future mitigation policies and preventive measures against nonoptimal temperatures should be specific to disease outcomes and targeted at susceptible populations. https://doi.org/10.1289/EHP12854.

Drivers of the time-varying heat-cold-mortality association in Spain: A longitudinal observational study

BACKGROUND

A number of studies have reported reductions in mortality risk due to heat and cold over time. However, questions remain about the drivers of these adaptation processes to ambient temperatures. We aimed to analyse the demographic and socioeconomic drivers of the downward trends in vulnerability to heat- and cold-related mortality observed in Spain during recent decades (1980-2018).

METHODS

We collected data on all-cause mortality, temperature and relevant contextual indicators for 48 provinces in mainland Spain and the Balearic Islands between Jan 1, 1980, and Dec 31, 2018. Fourteen contextual indicators were analysed representing ageing, isolation, urbanicity, heating, air conditioning (AC), house antiquity and ownership, education, life expectancy, macroeconomics, socioeconomics, and health investment. The statistical analysis was separately performed for the range of months mostly causing heat- (June-September) and cold- (October-May) related mortality. We first applied a quasi-Poisson generalised linear regression in combination with distributed lag non-linear models (DLNM) to estimate province-specific temperature-mortality associations for different periods, and then we fitted univariable and multivariable multilevel spatiotemporal meta-regression models to evaluate the effect modification of the contextual characteristics on heat- and cold-related mortality risks over time.

FINDINGS

The average annual mean temperature has risen at an average rate of 0·36 °C per decade in Spain over 1980-2012, although the increase in temperature has been more pronounced in summer (0·40 °C per decade in June-September) than during the rest of the year (0·33 °C per decade). This warming has been observed, however, in parallel with a progressive reduction in the mortality risk associated to both hot and cold temperatures. We found independent associations for AC with heat-related mortality, and heating with cold-related mortality. AC was responsible for about 28·6% (31·5%) of the decrease in deaths due to heat (extreme heat) between 1989 and 1993 and 2009-2013, and heating for about 38·3% (50·8%) of the reductions in deaths due to cold (extreme cold) temperatures. Ageing (ie, proportion of population over 64 years) attenuated the decrease in cold-related mortality.

INTERPRETATION

AC and heating are effective societal adaptive measures to heat and cold temperatures. This evidence holds important implications for climate change health adaptation policies, and for the projections of climate change impacts on human health.

Temperature modifies the association between air pollution and respiratory disease mortality in Cape Town, South Africa

The aim of this 10-year study was to investigate whether and how temperature modifies the association between daily ambient PM10, NO2, SO2 air pollution and daily respiratory disease mortality in Cape Town. A time-stratified case-crossover epidemiological design was applied. Susceptibility by sex and age groups (15-64 years and ≥65 years) was also investigated. On days with medium Tapp levels, NO2 displayed a stronger association with respiratory mortality than PM10 or SO2. Females appeared to be more susceptible to NO2 at medium Tapp levels to males. The 15-64-year-old age group seemed to be more vulnerable to NO2 and PM10 at medium Tapp levels compared to the elderly (≥65 years). At high Tapp levels, females were more susceptible to PM10. The 15-64-year-old group were more vulnerable to NO2 and SO2. The results can be used in present-day early warning systems and in risk assessments to estimate the impact of increased air pollution and temperature.

Association of atmospheric temperature with out-of-hospital natural deaths occurrence before and during the COVID-19 pandemic in Osaka, Japan

In this study, we aimed to investigate the relationship between out-of-hospital natural death (OHND) and ambient temperature and examine the seriousness of the impact of the coronavirus disease-2019 (COVID-19) pandemic on this relationship. We used data from the Osaka Prefectural Office of Medical Examiners between 2018 and 2022 and performed a retrospective observational study. A Poisson regression model was applied to examine the relationship between OHND and temperature in Osaka City. The relative risk of OHND at 5 °C and 32 °C compared to the minimum mortality temperature increased from 1.81 in the pre-COVID-19 period to 2.03 in the post-COVID-19 period at 5 °C and from 1.29 in the pre-COVID-19 period to 1.60 in the post-COVID-19 period at 32 °C. The increase in relative risk per 1 °C increase from the pre- to post-COVID-19 period was 1.0551 (rate ratio [RR], p = 0.003) in the hot environment and 1.0233 (RR, p = 0.013) in the cold environment, which was larger than that in the hot environment. Although the risk of OHND increased at both temperatures, the change in OHND risk during post-COVID-19 was larger in the hot environment than in the cold environment, implicating the effect of pandemics in the current scenario of global warming.

Asthma hospitalisations and heat exposure in England: a case-crossover study during 2002-2019

BACKGROUND

Previous studies have reported an association between warm temperature and asthma hospitalisation. They have reported different sex-related and age-related vulnerabilities; nevertheless, little is known about how this effect has changed over time and how it varies in space. This study aims to evaluate the association between asthma hospitalisation and warm temperature and investigate vulnerabilities by age, sex, time and space.

METHODS

We retrieved individual-level data on summer asthma hospitalisation at high temporal (daily) and spatial (postcodes) resolutions during 2002-2019 in England from the NHS Digital. Daily mean temperature at 1 km×1 km resolution was retrieved from the UK Met Office. We focused on lag 0-3 days. We employed a case-crossover study design and fitted Bayesian hierarchical Poisson models accounting for possible confounders (rainfall, relative humidity, wind speed and national holidays).

RESULTS

After accounting for confounding, we found an increase of 1.11% (95% credible interval: 0.88% to 1.34%) in the asthma hospitalisation risk for every 1°C increase in the ambient summer temperature. The effect was highest for males aged 16-64 (2.10%, 1.59% to 2.61%) and during the early years of our analysis. We also found evidence of a decreasing linear trend of the effect over time. Populations in Yorkshire and the Humber and East and West Midlands were the most vulnerable.

CONCLUSION

This study provides evidence of an association between warm temperature and hospital admission for asthma. The effect has decreased over time with potential explanations including temporal differences in patterns of heat exposure, adaptive mechanisms, asthma management, lifestyle, comorbidities and occupation.

Rapid increase in the risk of heat-related mortality

Heat-related mortality has been identified as one of the key climate extremes posing a risk to human health. Current research focuses largely on how heat mortality increases with mean global temperature rise, but it is unclear how much climate change will increase the frequency and severity of extreme summer seasons with high impact on human health. In this probabilistic analysis, we combined empirical heat-mortality relationships for 748 locations from 47 countries with climate model large ensemble data to identify probable past and future highly impactful summer seasons. Across most locations, heat mortality counts of a 1-in-100 year season in the climate of 2000 would be expected once every ten to twenty years in the climate of 2020. These return periods are projected to further shorten under warming levels of 1.5 °C and 2 °C, where heat-mortality extremes of the past climate will eventually become commonplace if no adaptation occurs. Our findings highlight the urgent need for strong mitigation and adaptation to reduce impacts on human lives.

The relative value of sociocultural and infrastructural adaptations to heat in a very hot climate in northern Australia: a case time series of heat-associated mortality

BACKGROUND

Climate change is increasing heat-associated mortality particularly in hotter parts of the world. The Northern Territory is a large and sparsely populated peri-equatorial state in Australia. The Northern Territory has the highest proportion of Aboriginal and Torres Strait Islander people in Australia (31%), most of whom live in remote communities of over 65 Aboriginal Nations defined by ancient social, cultural, and linguistic heritage. The remainder non-Indigenous population lives mostly within the two urban centres (Darwin in the Top End region and Alice Springs in the Centre region of the Northern Territory). Here we aim to compare non-Indigenous (eg, high income) and Indigenous societies in a tropical environment and explore the relative importance of physiological, sociocultural, and technological and infrastructural adaptations to heat.

METHODS

In this case time series, we matched temperature at the time of death using a modified distributed lag non-linear model for all deaths in the Northern Territory, Australia, from Jan 1, 1980, to Dec 31, 2019. Data on deaths came from the national registry of Births, Deaths and Marriages. Cases were excluded if location or date of death were not recorded or if the person was a non-resident. Daily maximum and minimum temperature were measured and recorded by the Bureau of Meteorology. Hot weather was defined as mean temperature greater than 35°C over a 3-day lag. Socioeconomic status as indicated by Index of Relative Socioeconomic Disadvantage was mapped from location at death.

FINDINGS

During the study period, 34 782 deaths were recorded; after exclusions 31 800 deaths were included in statistical analysis (15 801 Aboriginal and 15 999 non-Indigenous). There was no apparent reduction in heat susceptibility despite infrastructural and technological improvements for the majority non-Indigenous population over the study period with no heat-associated mortality in the first two decades (1980-99; relative risk 1·00 [95% CI 0·87-1·15]) compared with the second two decades (2000-19; 1·14 [1·01-1·29]). Despite marked socioeconomic inequity, Aboriginal people are not more susceptible to heat mortality (1·05, [0·95-1·18]) than non-Indigenous people (1·18 [1·06-1·29]).

INTERPRETATION

It is widely believed that technological and infrastructural adaptations are crucial in preparing for hotter climates; however, this study suggests that social and cultural adaptations to increasing hot weather are potentially powerful mechanisms for protecting human health. Although cool shelters are essential during extreme heat, research is required to determine whether excessive exposure to air-conditioned spaces might impair physiological acclimatisation to the prevailing environment. Understanding sociocultural practices from past and ancient societies provides insight into non-technological adaptation opportunities that are protective of health.

FUNDING

None.

Heat-related mortality in Europe during the summer of 2022

Over 70,000 excess deaths occurred in Europe during the summer of 2003. The resulting societal awareness led to the design and implementation of adaptation strategies to protect at-risk populations. We aimed to quantify heat-related mortality burden during the summer of 2022, the hottest season on record in Europe. We analyzed the Eurostat mortality database, which includes 45,184,044 counts of death from 823 contiguous regions in 35 European countries, representing the whole population of over 543 million people. We estimated 61,672 (95% confidence interval (CI) = 37,643-86,807) heat-related deaths in Europe between 30 May and 4 September 2022. Italy (18,010 deaths; 95% CI = 13,793-22,225), Spain (11,324; 95% CI = 7,908-14,880) and Germany (8,173; 95% CI = 5,374-11,018) had the highest summer heat-related mortality numbers, while Italy (295 deaths per million, 95% CI = 226-364), Greece (280, 95% CI = 201-355), Spain (237, 95% CI = 166-312) and Portugal (211, 95% CI = 162-255) had the highest heat-related mortality rates. Relative to population, we estimated 56% more heat-related deaths in women than men, with higher rates in men aged 0-64 (+41%) and 65-79 (+14%) years, and in women aged 80+ years (+27%). Our results call for a reevaluation and strengthening of existing heat surveillance platforms, prevention plans and long-term adaptation strategies.

Changes in the temperature-mortality relationship in France: Limited evidence of adaptation to a new climate

CONTEXT

Documenting trends in the health impacts of ambient temperature is key to supporting adaptation strategies to climate change. This paper explores changes in the temperature-related mortality in 18 French urban centers between 1970 and 2015.

METHOD

A multicentric time-series design with time-varying distributed lag nonlinear models was adopted to model the shape of the relationship and assess temporal changes in risks and impacts.

RESULTS

The general shape of the temperature-mortality relationship did not change over time, except for an increasing risk at very low percentiles and a decreasing risk at very high percentiles. The relative risk at the 99.9^th percentile compared to the 50^th percentile of the 1970-2015 temperature distribution decreased from 2.33 [95% confidence interval (CI): 1.95:2.79] in 1975 to 1.33 [95% CI: 1.14:1.55] in 2015. Between 1970 and 2015, 302,456 [95% CI: 292,723:311,392] deaths were attributable to non-optimal temperatures, corresponding to 5.5% [95% CI: 5.3:5.6] of total mortality. This burden decreased progressively, representing 7.2% [95% CI: 6.7:7.7] of total mortality in the 1970s to 3.4% [95% CI: 3.2:3.6] in the 2000s. However, the contribution of hot temperatures to this burden (higher than the 90^th percentile) increased.

DISCUSSION

Despite the decreasing relative risk, the fraction of mortality attributable to extreme heat increased between 1970 and 2015, thus highlighting the need for proactive adaptation.

Reconstruction of the hourly fine-resolution apparent temperature (Humidex) with the aerodynamic parameters

Apparent temperature is the preferred measure of hotness or coldness expressed to depict the human sense. Spatially explicit measurement of the hourly apparent temperature is essential for capturing the threats to bioclimatic comfort and preventing potential mortality/morbidity risk from heat or cold. However, existing apparent temperature products only provide daily observations at the spatial resolution of several dozen kilometers, resulting in some substantial underestimations for some life-threatening thermal stresses highly localized in space and time. Furthermore, some data-driven models lack mechanical constraints on the turbulent exchange between the surface and the atmosphere, making some unsatisfactory accuracy. Here, we propose Humidex reconstruction model incorporating atmospheric dynamics theory and aerodynamic parameters (i.e., heat and momentum roughness lengths for natural surfaces and three urban canopy geometry parameters for artificial surfaces), capable of developing an hourly dataset at fine-grained spatial resolution (0.01° × 0.01°). In this study, a total of 2952 h in four seasons were selected to test the seasonal performance of this model, taking the Yangtze River Delta as an example. The results show that the Humidex products from this model generally outperform the existing comparable products, with the hourly population root mean square error (RMSE) ranging from 1 to 2 °C in winter and autumn and 2-3 °C in spring and summer. Moreover, the constraint of aerodynamic parameters can reduce RMSE with a significant margin for each season, up to 2 °C, especially in areas with dense woodlands or buildings. In addition, the results demonstrate the excellent performance of this model in capturing short-lived thermal health threats, which are easily overlooked when observed data only provides a daily variation. This indicates that the model can allow researchers and practitioners investigate the fine-grained spatial and temporal evolution of thermal stress and its impact on public health, tourism, learning, and work performance.

The Association Between High Ambient Temperature and Mortality in the Mediterranean Basin: a Systematic Review and Meta-analysis

PURPOSE OF REVIEW

The Mediterranean basin is highly vulnerable to climate change. This study is aimed at quantifying the risk of mortality associated with exposure to high ambient temperature in the Mediterranean basin in the general population and in vulnerable sub-populations.

RECENT FINDINGS

We retrieved effect estimates from studies linking temperature and mortality in the Mediterranean basin, between 2000 and 2021. In a meta-analysis of 16 studies, we found an increased risk of all-cause mortality due to ambient heat/high temperature exposure in the Mediterranean basin, with a pooled RR of 1.035 (95%CI 1.028-1.041) per 1 °C increase in temperature above local thresholds (I² = 79%). Risk was highest for respiratory mortality (RR = 1.063, 95% CI 1.052-1.074) and cardiovascular mortality (RR = 1.046, 95% CI 1.036-1.057). Hot ambient temperatures increase the mortality risk across the Mediterranean basin. Further studies, especially in North African, Asian Mediterranean, and eastern European countries, are needed to bolster regional preparedness against future heat-related health burdens.

Have residents adapted to heat wave and cold spell in the 21st century? Evidence from 136 Chinese cities

Global climate change has increased the probability and intensity of extreme weather events. The adverse health effect of extreme temperature has gone through a temporal variation over years. Time-series data including city-level daily cardiovascular death records and meteorological data were collected from 136 Chinese cities during 2006 and 2019. A time-varying distributed lag model with interaction terms was applied to assess the temporal change of mortality risk and attributable mortality of heat wave and cold spell. The mortality effect of heat wave generally increased and that of cold spell decreased significantly in the total population during the study period. The heat wave effect increased especially among the female and people aged 65 to 74. As for the cold spell, the reduced susceptibility was detected both in the temperate and cold climatic zone. Our findings appeal for counterpart measures corresponding to sub-populations and regions responding to future extreme climate events from the public and individuals.

Daily temperature effects on under-five mortality in a tropical climate country and the role of local characteristics

BACKGROUND

Climate change and its subsequent effects on temperature have raised global public health concerns. Although numerous epidemiological studies have shown the adverse health effects of temperature, the association remains unclear for children aged below five years old and those in tropical climate regions.

METHODS

We conducted a two-stage time-stratified case-crossover study to examine the association between temperature and under-five mortality, spanning the period from 2014 to 2018 across all six regions in Malaysia. In the first stage, we estimated region-specific temperature-mortality associations using a conditional Poisson regression and distributed lag nonlinear models. We used a multivariate meta-regression model to pool the region-specific estimates and examine the potential role of local characteristics in the association, which includes geographical information, demographics, socioeconomic status, long-term temperature metrics, and healthcare access by region.

RESULTS

Temperature in Malaysia ranged from 22 °C to 31 °C, with a mean of 27.6 °C. No clear seasonality was observed in under-five mortality. We found no strong evidence of the association between temperature and under-five mortality, with an "M-" shaped exposure-response curve. The minimum mortality temperature (MMT) was identified at 27.1 °C. Among several local characteristics, only education level and hospital bed rates reduced the residual heterogeneity in the association. However, effect modification by these variables were not significant.

CONCLUSION

This study suggests a null association between temperature and under-five mortality in Malaysia, which has a tropical climate. The "M-" shaped pattern suggests that under-fives may be vulnerable to temperature changes, even with a small temperature change in reference to the MMT. However, the weak risks with a large uncertainty at extreme temperatures remained inconclusive. Potential roles of education level and hospital bed rate were statistically inconclusive.

Temporal variation of the temperature-mortality association in Spain: a nationwide analysis

BACKGROUND

Although adaptation to continuously rising ambient temperatures is an emerging topic and has been widely studied at a global scale, detailed analysis of the joint indicators for long-term adaptation in Spain are scarce. This study aims to explore temporal variations of the minimum mortality temperature and mortality burden from heat and cold between 1979 and 2018.

METHODS

We collected individual all-cause mortality and climate reanalysis data for 4 decades at a daily time step. To estimate the temperature-mortality association for each decade, we fitted a quasi-Poisson time-series regression model using a distributed lag non-linear model with 21 days of lag, controlling for trends and day of the week. We also calculated attributable mortality fractions by age and sex for heat and cold, defined as temperatures above and below the optimum temperature, which corresponds to the minimum mortality in each period.

RESULTS

We analysed over 14 million deaths registered in Spain between 1979 and 2018. The optimum temperature estimated at a nationwide scale declined from 21 °C in 1979-1988 to 16 °C in 1999-2008, and raised to 18 °C in 2009-2018. The mortality burden from moderate cold showed a 3-fold reduction down to 2.4% in 2009-2018. Since 1988-1999, the mortality risk attributable to moderate (extreme) heat reduced from 0.9% (0.8%) to 0.6% (0.5%). The mortality risk due to heat in women was almost 2 times larger than in men, and did not decrease over time.

CONCLUSION

Despite the progressively warmer temperatures in Spain, we observed a persistent flattening of the exposure-response curves, which marked an expansion of the uncertainty range of the optimal temperatures. Adaptation has been produced to some extent in a non-uniform manner with a substantial decrease in cold-related mortality, while for heat it became more apparent in the most recent decade only.

Climate change and human health in the Eastern Mediterranean and Middle East: Literature review, research priorities and policy suggestions

Human health is linked to climatic factors in complex ways, and climate change can have profound direct and indirect impacts on the health status of any given region. Susceptibility to climate change is modulated by biological, ecological and socio-political factors such as age, gender, geographic location, socio-economic status, occupation, health status and housing conditions, among other. In the Eastern Mediterranean and Middle East (EMME), climatic factors known to affect human health include extreme heat, water shortages and air pollution. Furthermore, the epidemiology of vector-borne diseases (VBDs) and the health consequences of population displacement are also influenced by climate change in this region. To inform future policies for adaptation and mitigation measures, and based on an extensive review of the available knowledge, we recommend several research priorities for the region. These include the generation of more empirical evidence on exposure-response functions involving climate change and specific health outcomes, the development of appropriate methodologies to evaluate the physical and psychological effects of climate change on vulnerable populations, determining how climate change alters the ecological determinants of human health, improving our understanding of the effects of long-term exposure to heat stress and air pollution, and evaluating the interactions between adaptation and mitigation strategies. Because national boundaries do not limit most climate-related factors expected to impact human health, we propose that adaptation/mitigation policies must have a regional scope, and therefore require collaborative efforts among EMME nations. Policy suggestions include a decisive region-wide decarbonisation, the integration of environmentally driven morbidity and mortality data throughout the region, advancing the development and widespread use of affordable technologies for the production and management of drinking water by non-traditional means, the development of comprehensive strategies to improve the health status of displaced populations, and fostering regional networks for monitoring and controlling the spread of infectious diseases and disease vectors.

The Impact of Ambient Temperature on Cardiorespiratory Mortality in Northern Greece

It is well-established that exposure to non-optimum temperatures adversely affects public health, with the negative impact varying with latitude, as well as various climatic and population characteristics. This work aims to assess the relationship between ambient temperature and mortality from cardiorespiratory diseases in Eastern Macedonia and Thrace, in Northern Greece. For this, a standard time-series over-dispersed Poisson regression was fit, along with a distributed lag nonlinear model (DLNM), using a maximum lag of 21 days, to capture the non-linear and delayed temperature-related effects. A U-shaped relationship was found between temperature and cardiorespiratory mortality for the overall population and various subgroups and the minimum mortality temperature was observed around the 65th percentile of the temperature distribution. Exposure to extremely high temperatures was found to put the highest risk of cardiorespiratory mortality in all cases, except for females which were found to be more sensitive to extreme cold. It is remarkable that the highest burden of temperature-related mortality was attributed to moderate temperatures and primarily to moderate cold. The elderly were found to be particularly susceptible to both cold and hot thermal stress. These results provide new evidence on the health response of the population to low and high temperatures and could be useful to local authorities and policy-makers for developing interventions and prevention strategies for reducing the adverse impact of ambient temperature.

Association between temperature and natural mortality in Belgium: Effect modification by individual characteristics and residential environment

BACKGROUND

There is strong evidence of mortality being associated to extreme temperatures but the extent to which individual or residential factors modulate this temperature vulnerability is less clear.

METHODS

We conducted a multi-city study with a time-stratified case-crossover design and used conditional logistic regression to examine the association between extreme temperatures and overall natural and cause-specific mortality. City-specific estimates were pooled using a random-effect meta-analysis to describe the global association. Cold and heat effects were assessed by comparing the mortality risks corresponding to the 2.5th and 97.5th percentiles of the daily temperature, respectively, with the minimum mortality temperature. For cold, we cumulated the risk over lags of 0 to 28 days before death and 0 to 7 days for heat. We carried out stratified analyses and assessed effect modification by individual characteristics, preexisting chronic health conditions and residential environment (population density, built-up area and air pollutants: PM2.5, NO2, O3 and black carbon) to identify more vulnerable population subgroups.

RESULTS

Based on 307,859 deaths from natural causes, we found significant cold effect (OR = 1.42, 95%CI: 1.30-1.57) and heat effect (OR = 1.17, 95%CI: 1.12-1.21) for overall natural mortality and for respiratory causes in particular. There were significant effects modifications for some health conditions: people with asthma were at higher risk for cold, and people with psychoses for heat. In addition, people with long or frequent hospital admissions in the year preceding death were at lower risk. Despite large uncertainties, there was suggestion of effect modification by air pollutants: the effect of heat was higher on more polluted days of O3 and black carbon, and a higher cold effect was observed on more polluted days of PM2.5 and NO2 while for O3, the effect was lower.

CONCLUSIONS

These findings allow for targeted planning of public-health measures aiming to prevent the effects of extreme temperatures.

Trends in Temperature-associated Mortality in São Paulo (Brazil) between 2000 and 2018: an Example of Disparities in Adaptation to Cold and Heat

Exposure to non-optimal temperatures remains the single most deathful direct climate change impact to health. The risk varies based on the adaptation capacity of the exposed population which can be driven by climatic and/or non-climatic factors subject to fluctuations over time. We investigated temporal changes in the exposure-response relationship between daily mean temperature and mortality by cause of death, sex, age, and ethnicity in the megacity of São Paulo, Brazil (2000-2018). We fitted a quasi-Poisson regression model with time-varying distributed-lag non-linear model (tv-DLNM) to obtain annual estimates. We used two indicators of adaptation: trends in the annual minimum mortality temperature (MMT), i.e., temperature at which the mortality rate is the lowest, and in the cumulative relative risk (cRR) associated with extreme cold and heat. Finally, we evaluated their association with annual mean temperature and annual extreme cold and heat, respectively to assess the role of climatic and non-climatic drivers. In total, we investigated 4,471,000 deaths from non-external causes. We found significant temporal trends for both the MMT and cRR indicators. The former was decoupled from changes in AMT, whereas the latter showed some degree of alignment with extreme heat and cold, suggesting the role of both climatic and non-climatic adaptation drivers. Finally, changes in MMT and cRR varied substantially by sex, age, and ethnicity, exposing disparities in the adaptation capacity of these population groups. Our findings support the need for group-specific interventions and regular monitoring of the health risk to non-optimal temperatures to inform urban public health policies.

Temperature-related chest pain presentations and future projections with climate change

BACKGROUND

Climate change has led to increased interest in studying adverse health effects relating to ambient temperatures. It is unclear whether incident chest pain is associated with non-optimal temperatures and how chest pain presentation rates might be affected by climate change.

METHODS

The study included ambulance data of chest pain presentations in Melbourne, Australia from 1/1/2015 to 30/6/2019 with linkage to hospital and emergency discharge diagnosis data. A time series quasi-Poisson regression with a distributed lag nonlinear model was fitted to assess the temperature-chest pain presentation associations overall and according to age, sex, socioeconomic status, and event location subgroups, with adjustment for season, day of the week and long-term trend. Future excess chest pain presentations associated with cold and heat were projected under six general circulation models under medium and high emission scenarios.

RESULTS

In 206,789 chest pain presentations, mean (SD) age was 61.2 (18.9) years and 50.3 % were female. Significant heat- and cold-related increased risk of chest pain presentations were observed for mean air temperatures above and below 20.8 °C, respectively. Excess chest pain presentations related to heat were observed in all subgroups, but appeared to be attenuated for older patients (≥70 years), patients of higher socioeconomic status (SES), and patients developing chest pain at home. We projected increases in heat-related chest pain presentations with climate change under both medium- and high-emission scenarios, which are offset by decreases in chest pain presentations related to cold temperatures.

CONCLUSIONS

Heat- and cold- exposure appear to increase the risk of chest pain presentations, especially among younger patients and patients of lower SES. This will have important implications with climate change modelling of chest pain, in particular highlighting the importance of risk mitigation strategies to minimise adverse health impacts on hotter days.

Evolution of temperature-attributable mortality trends looking at social inequalities: An observational case study of urban maladaptation to cold and heat

BACKGROUND

To date, little is known about the temporal variation of the temperature-mortality association among different demographic and socio-economic groups. The aim of this work is to investigate trends in cold- and heat- attributable mortality risk and burden by sex, age, education, marital status, and number of household occupants in the city of Turin, Italy.

METHODS

We collected daily time-series of temperature and mortality counts by demographic and socio-economic groups for the period 1982-2018 in Turin. We applied standard quasi-Poisson regression models to data subsets of 25-year moving subperiods, and we estimated the temperature-mortality associations with distributed lag non-linear models (DLNM). We provided cross-linkages between the evolution of minimum mortality temperatures, relative risks of mortality and temperature-attributable deaths under cold and hot conditions.

RESULTS

Our findings highlighted an overall increase in risk trends under cold and heat conditions. All-cause mortality at the 1st percentile increased from 1.15 (95% CI: 1.04; 1.28) in 1982-2006 to 1.24 (95% CI: 1.11; 1.38) in 1994-2018, while at the 99th percentile the risk shifted from 1.51 (95% CI: 1.41; 1.61) to 1.59 (95% CI: 1.49; 1.71). In relation to social differences, women were characterized by greater values in respect to men, and similar estimates were observed among the elderly in respect to the youngest subgroup. Risk trends by educational subgroups were mixed, according to the reference temperature condition. Finally, individuals living in conditions of isolation were characterized by higher risks, with an increasing vulnerability throughout time.

CONCLUSIONS

The overall increase in cold- and heat- related mortality risk suggests a maladaptation to ambient temperatures in Turin. Despite alert systems in place increase public awareness and improve the efficiency of existing health services at the local level, they do not necessarily prevent risks in a homogeneous way. Targeted public health responses to cold and heat in Turin are urgently needed to adapt to extreme temperatures due to climate change.

A global comprehensive analysis of ambient low temperature and non-communicable diseases burden during 1990-2019

Climate change and health are inextricably linked, especially the role of ambient temperature. This study aimed to analyze the non-communicable disease (NCD) burden attributable to low temperature globally, regionally, and temporally using data from the Global Burden of Disease (GBD) study 2019. Globally, in 2019, low temperature was responsible for 5.42% DALY and 7.18% death of NCDs, representing the age-standardized disability-adjusted life years (DALY) and death rates (per 100,000 population) of 359.6 (95% uncertainty intervals (UI): 306.09, 416.88) and 21.36 (95% UI:18.26, 24.74). Ischemic heart disease was the first leading cause of DALY and death resulting from low temperature, followed by stroke. However, age-standardized DALY and death rates attributable to low temperature have exhibited wide variability across regions, with the highest in Central Asia and Eastern Europe and the lowest in Caribbean and Western sub-Saharan Africa. During the study period (1990-2019), there has been a significant decrease in the burden of NCDs attributable to low temperature, but progress has been uneven across countries, whereas nations exhibiting high sociodemographic index (SDI) declined more significantly compared with low SDI nations. Notably, three nations, including Uzbekistan, Tajikistan, and Lesotho, had the maximum NCDs burden attributed to low temperature and displayed an upward trend. In conclusion, ambient low temperature contributes to substantial NCD burden with notable geographical variations.

Association between ambient temperature and age-specific mortality from the elderly: Epidemiological evidence from the Chinese prefecture with most serious aging

Older people are main susceptible group affected by non-optimal temperature. The aim of the study was to determine how mortality of older people with different ages are affected by temperatures. For this study, we collected data of all-cause death of 256,037 people aged between 65 and 104 years of age from a prefecture located in the north subtropical area with most serious aging rate in 2000, 2010 and 2020 in China. A distributed lag nonlinear model under different age groups was used to estimate non-optimal temperature associations to mortality. The results revealed: (1) With increasing age, older people were more likely to die during moderate low temperature, the proportion of attributable fraction of moderate low temperature in all temperature gradually increased with age. (2) Moderate low temperature could be divided into two parts, the lower part caused most death at age 65-79 and the higher part was not so dangerous, while for age 80+, preventive actions should be taken for both parts. (3) A leveling-off and deceleration phenomenon was observed at age 95-99 for low temperature, but not 100-104, it may be virtually a consequence of "harvesting effect" in that susceptible and common people have died before age 95, it was coincidence with mortality deceleration at extreme old ages found by demographic scholars over the past 200 years. (4) Heat wave had much higher relative risk than cold spell compared with moderate high and low temperature because of steeper slope of relative risk at the period of moderate-extreme conversion of high temperature, the older people should pay more attention to weather with moderate-extreme conversion of high temperature. Furthermore, our findings could help improve the understanding of non-optimal temperature on health of older people and support the development of response strategies for different seasons at different ages.