Cardiovascular mortality risks during the 2017 exceptional heatwaves in China

Epidemiology of Ischemic Heart Disease Burden Attributable to High Temperature in Asia From GBD 2021

BACKGROUND

Ischemic heart disease (IHD) posed the highest global disease burden in 2021, with regional disparities in Asia. Moreover, climate change is exacerbating population exposure to high temperatures (Hi-Tem).

OBJECTIVES

This study aimed to systematically assess the burden of IHD attributed to Hi-Tem in Asia, considering geographic and demographic factors.

METHODS

The Global Burden of Disease Study 2021 tools evaluated the IHD burden from Hi-Tem in Asia, and decomposition analysis was conducted to further explore the potential burden drivers.

RESULTS

Asia witnessed a significant increase in IHD burden caused by Hi-Tem, with 88,450 (95% UI: 15,815-188,816) deaths and 2,112,025.42 (95% UI: 456,758.65-4,325,643.47) disability-adjusted life years in 2021. Over the past 3 decades, the burden increased annually by 1.63% (95% CI: 1.25%-2.01%) in age-standardized mortality rate and by 1.60% (95% CI: 1.21%-1.99%) in age-standardized rate of disability-adjusted life years. Notably, South Asia bore the heaviest burden, whereas high-income Asia Pacific had the lightest. Men and older persons consistently faced a higher IHD burden from Hi-Tem. Despite generally balanced contributions from population growth, aging, and epidemiological changes, regional disparities may persist.

CONCLUSIONS

Our study provides a comprehensive overview of the demographic and geographic characteristics of the IHD burden attributable to Hi-Tem in Asia from 1990 to 2021. In summary, Asia's IHD burden caused by Hi-Tem rose significantly, with the greater impact on men and older populations.

Association between ambient temperature and couple fecundity: Insights from a large-scale cohort study in Yunnan, China

BACKGROUND

Direct evidence linking ambient temperature to human fecundity is sparse. We aimed to evaluate the potential impact of ambient temperature on time to pregnancy (TTP) and identify the optimal temperature range for initiating conception attempts.

METHODS

Our analysis included 576 927 couples from the Chinese National Free Preconception Health Examination Project (NFPHEP) in Yunnan Province, with a one-year follow-up post-enrollment. Each female partner's cycle-specific average temperatures (Tmean) at the couple residences were aggregated and summarized by daily concentrations with a resolution of 0.1° × 0.1°. We used discrete-time Cox regression nested with distributed lag non-linear models to estimate the fecundity odds ratio (FOR) for Tmean concerning one-, two-, or three-cycle preceding pregnancy attempts.

RESULTS

Among the 576 927 couples (mean [SD] age: female partner, 27.6 [5.5] years; male partner, 30.1 [5.8] years), 193 710 couples conceived within 12 cycles, among which 52.1% were pregnant within 3 TTPs and 78.9% were pregnant within 6 TTPs. The cumulative pregnancy rate in 12 menstrual cycles was 38.87%. An inverted U-shaped exposure-response relationship between TTP and Tmean was identified for the cycles preceding the pregnancy attempt. The optimal temperature interval (TI) for conception attempts was determined to be 7.9 °C to 14.5 °C, correlating with a 0.3% (FOR: 1.003, 95%CI: 0.987-1.020) to 3.8% (FOR:1.038, 95%CI: 1.031-1.047) increase in fecundity, compared to the median Tmean of 15.9 °C. Temperatures below or above this interval were linked to a significant reduction in fecundity, ranging from 1.2% (FOR: 0.988, 95%CI: 0.977-1.000) to 6.8% (FOR: 0.932, 95%CI: 0.910-0.953) for the lower TI (<7.9 °C), 2.3% (FOR: 0.977, 95%CI: 0.970-0.984) to 6.6% (FOR: 0.934, 95%CI: 0.921-0.948) for the higher TI (14.5 °C-24.6 °C), respectively, compared to the optimal TI. These findings were robust after stratifying by age and BMI of female or male partners.

CONCLUSION

Exposure to temperatures within the 7.9 °C to 14.5 °C, one to three menstrual cycles preceding pregnancy attempts, was associated with enhanced fecundity and a reduced TTP, suggesting that the optimal ambient temperature could be pivotal for conception success.

Spatio-temporal variations of heat extremes across the yangtze river delta during 2001-2023 based on remotely sensed seamless air temperature

Heat extremes become increasingly frequent and severe, posing adverse risks to public health and environment. Previous research on extreme heat mostly used meteorological observations or reanalysis data, which cannot well capture detailed spatial patterns. This study developed a seamless air temperature (Ta) dataset from remote sensing data to characterize the spatio-temporal variations of heat extremes in the Yangtze River Delta (YRD) from 2001 to 2023. First, the daily maximum Ta of cloud-free pixels was estimated through machine learning algorithms from MODIS land surface temperature (LST) and other remote sensing data. Then, gaps in the estimated Ta caused by cloud cover were filled using the Temporal Fourier Analysis (TFA) method, generating a seamless daily maximum Ta dataset. The remotely sensed Ta achieved an overall MAE of 1.11 °C. Based on the remotely sensed Ta, six heat indices were calculated to characterize heat extremes, including heat days (HTD), effective accumulated high temperature (EAHT), heatwave frequency (HWF), cumulative heatwave days (HWD), maximum heatwave duration (HWMD) and average heatwave duration (HWAD). Heat extremes occurred frequently in the YRD, with obvious spatial variability. Southern basins experienced intense heat with high frequency and duration, while southern mountains and northern areas experienced weaker heat extremes. Urban areas have substantially more intense heat events than suburbs, attributed to urban heat island effect. 2022 recorded the most severe heat, with notable events also in 2013 and 2003. This study provides valuable insights into heat events in the YRD and serves as a reference for remote sensing research on heat events.

Mental health disparities among maternal populations following heatwave exposure in North Carolina (2011-2019): a matched analysis

Background

The increasing incidence of extreme heat due to climate change poses a significant threat to maternal mental health in the U.S. We examine the association of acute exposure to heatwaves with maternal mental health conditions in North Carolina from 2011 to 2019.

Methods

We incorporate a matched analysis design using NC Hospital Discharge Data to examine emergency department admissions for psychiatric conditions during the warm season (May to September), matching heatwave periods with non-heatwave unexposed periods at the zip code tabulation area (ZCTA) level. We stratify the sample to examine effect modification across the rural-urban continuum, physiographic regions, measurements of neighborhood racial and economic inequality, and individual-level sociodemographic factors (e.g., age, race/ethnicity, and insurance type).

Findings

Our sample of 324,928 emergency department visits by pregnant individuals has a mean age of 25.8 years (SD: 5.84), with 9.3% (n = 30,205) identifying as Hispanic. Relative risk (RR) estimates and 95% confidence intervals (CI) indicate significant increases in maternal mental health burdens following heatwave exposure. Acute heatwave periods were associated with a 13% higher risk of severe mental illness (RRSMI: 1.13, CI: 1.08-1.19, p: <0.0001), while prolonged exposure to moderate-intensity heatwaves was associated with 37% higher risk (RRSMI: 1.37, CI: 1.19-1.58, p: <0.001). Individual factors (e.g., advanced maternal age and insurance providers) and neighborhood-level characteristics, like low socioeconomic status, racialized and economic segregation, rurality, and physiographic region, further modified the risk of adverse maternal mental health outcomes.

Interpretation

Our results add to the growing evidence of the impact of extreme heat on maternal mental health, particularly among vulnerable subpopulations. Additionally, findings emphasize the influence of socioeconomic and environmental contexts on mental health responses to heatwave exposure.

Funding

This work was supported by the Faculty Early Career Development Program (CAREER) award (grant #2044839) from the National Science Foundation and the National Institute of Environmental Health Sciences (NIEHS) award (grant #5R03ES035170-02).

The graded heat-health risk forecast and early warning with full-season coverage across China: a predicting model development and evaluation study

Background

Due to global climate change, high temperature and heatwaves have become critical issues that pose a threat to human health. An effective early warning system is essential to mitigate the health risks associated with high temperature and heatwaves. However, most of the current heatwave early warning systems are not adequately developed based on the heat-health risk model, and the health impact of hot weather has not been well managed in most countries.

Methods

This study proposed a "full-season coverage and population health-oriented graded early-warning" concept and developed a heat-health surveillance, forecast and early warning (HHSEW) model. The exposure-response (E-R) relationship between temperature and mortality was analyzed through a two-stage approach using time-series analysis data from 323 counties across China for the period 2013-2018. The premature mortality curve at each temperature percentile was plotted and four temperature-percentile points on the curve were determined as the thresholds of the pre-warning and warning levels 1-3 based on the variations in the rates of the segmental slopes on the curve. The HHSEW model was evaluated by comparing the frequency, the mortality risk of all-cause and cause-specific diseases, the predicted numbers of premature deaths, and the heat-related health economic burden at each warning level with those of the current high temperature early warning systems.

Findings

The HHSEW model determined five levels, including seasonal surveillance, pre-warning, and warning levels 1-3. There was a gradual increase in the mortality risks of all-cause and cause-specific diseases along with the increase of warning levels. The risk of all-cause mortality increased by 9.79% (95% CI: 8.59%-11.01%), 22.62% (95% CI: 19.49%-25.83%), 28.36% (95% CI: 24.72%-32.10%), and 33.87% (95% CI: 28.89%-39.06%) at the pre-warning level, warning level 1, warning level 2, and warning level 3, respectively. Through our HHSEW model, 94,008 heat-related all-cause deaths were predicted annually in the 337 major cities of China, which was much larger than the number (14,858) of the China Meteorological Administration (CMA) heatwave early-warning system currently used in China. It was estimated that the proper implementation of the HHSEW-based early warning system would save 220 billion CNY in heat-related health burden compared to the current heatwave early-warning system.

Interpretation

The HHSEW model has been proven to surpass the current heatwave early warning system. With its full-season coverage and graded warning levels for heat-related health risks, the HHSEW model and system can provide timely early warnings to the public, leading to significant health benefits. This methodology, labeled "full-season coverage and population health-oriented graded early-warning", should be implemented globally to mitigate the escalating health risks associated with high temperature.

Funding

National Natural Science Foundation of China (82425051, 42071433, 42305196, 82241051) and the Special Foundation of Basic Science and Technology Resources Survey of Ministry of Science and Technology of China (2017FY101204).

The 2023 report of the synergetic roadmap on carbon neutrality and clean air for China: Carbon reduction, pollution mitigation, greening, and growth

The response to climate change and air pollution control demonstrates strong synergy across scientific mechanisms, targets, strategies, and governance systems. This report, based on a monitoring indicator system for coordinated governance of air pollution and climate change, employs an interdisciplinary approach combining natural and social sciences. It establishes 20 indicators across five key areas: air pollution and climate change, governance systems and practices, structural transformation and technologies, atmospheric components and emission reduction pathways, and health impacts and co-benefits. This report tries to provide actionable insights into the interconnectedness of air pollution and climate governance. It highlights key policy gaps, presents updated indicators, and offers a refined monitoring framework to track progress toward China's dual goals of reducing emissions and improving air quality. Compared to previous editions, this year's report has updated four key indicators: meteorological impacts on air quality, climate change and its effects, governance policies, and low-carbon building energy systems. The aim is to further refine the monitoring framework, track progress, and establish a comprehensive theory for collaborative governance while identifying challenges and proposing solutions for China's pathway to carbon neutrality and clean air. The report comprises six chapters. The executive summary chapter is followed by analyzing air pollution and climate change interactions. Governance systems and practices are discussed in the third chapter, focusing on policy implementation and local experiences. The fourth chapter addresses structural transformations and emission reduction technologies, including energy and industrial shifts, transportation, low-carbon buildings, carbon capture and storage, and power systems. The fifth chapter outlines atmospheric component dynamics and emission pathways, presenting insights into emission drivers and future strategies. The sixth chapter assesses health impacts and the benefits of coordinated actions. Since 2019, China Clean Air Policy Partnership has produced annual reports on China's progress in climate and air pollution governance, receiving positive feedback. In 2023, the report was co-developed with Tsinghua University's Carbon Neutrality Research Institute, involving over 100 experts and multiple academic forums. The collaboration aims to continuously improve the indicator system and establish the report as a key resource supporting China's efforts in pollution reduction, carbon mitigation, greening, and sustainable growth.

Association of Ozone and Temperature with Ischemic Heart Disease Mortality Risk: Mediation and Interaction Analyses

Global warming and elevated ozone (O3) levels are gradually gaining widespread attention, and exposure to which may cause many physiological changes associated with cardiovascular events such as hypertension, cardiomyocyte apoptosis, etc. In addition, ischemic heart disease (IHD) is the leading cause of death worldwide. However, the contributions of temperature and O3, independently or in combination, to IHD mortality are not well understood. This study employs a two-stage analytical protocol (generalized additive model followed by meta-analysis) to explore the respective associations of temperature and O3 with IHD mortality, and determine their possible mediation and interaction effects. Our results suggest that increases of 10 μg/m3 in O3 and 1 °C in temperature at lag01 day are associated with increased IHD mortality risks of 0.789% and 0.686%, respectively. O3 can mediate the relationship between temperature and IHD mortality, with a pooled estimate of 0.140%, while temperature can mediate the association between O3 and IHD mortality, with a pooled estimate of 0.162%. The additive and multiplicative interaction effects of O3 and temperature were significantly associated with IHD mortality. The study findings demonstrate that higher temperature and O3 concentrations can increase human IHD mortality risk through interaction and mediation effects, providing a scientific basis for the synergistic management of temperature and O3 or associated interventions.

Extreme temperature events, functional dependency, and cardiometabolic multimorbidity: Insights from a national cohort study in China

BACKGROUND

Extreme temperature events (ETEs), including heatwaves and cold spells, are attracting increasing attention because of their impacts on human health. However, the association between ETEs and cardiometabolic multimorbidity (CMM) and the role of functional dependency in this relationship remain unclear.

METHODS

A prospective cohort study was conducted using data from the China Health and Retirement Longitudinal Study (CHARLS) from 2011 to 2020, considering 12 definitions each for heatwaves and cold spells, and three levels of functional dependency. Mixed Cox models with time-varying variables were used to comprehensively assess the independent and combined effects of ETEs and functional dependency on CMM. Additionally, subgroup analyses were conducted to investigate whether the relationship between ETEs and CMM was modified by the baseline characteristics.

RESULTS

Heatwave and cold spell exposures were associated with an increased risk of CMM (HR range: 1.028-1.102 and 1.046-1.187, respectively). Compared to participants with normal functional abilities, the risk of CMM increased with higher levels of functional dependency (HR range: 1.938-2.185). ETEs exposure and functional dependency are jointly associated with CMM risk. Participants with high-intensity ETEs exposure and high functional dependency had the greatest risk of developing CMM. Participants aged 60 and above were more susceptible to the effects of ETEs on CMM. Additionally, urban residents and those in northern regions were more vulnerable to heatwaves.

CONCLUSION

Both ETEs exposure and functional dependency increase the risk of developing CMM. Participants with functional dependency exposed to high-intensity ETEs faced the highest risk of developing CMM. These findings highlight the significant impact of ETEs on CMM and the importance of protecting vulnerable populations during periods of extreme temperature.

Projecting future excess deaths associated with extreme precipitation events in China under changing climate: an integrated modelling study

BACKGROUND

Climate-change-induced extreme precipitation events have attracted global attention; however, the associated excess deaths burden has been insufficiently explored and remains unclear.

METHODS

We first defined an extreme precipitation event for each county when the daily total precipitation exceeded the county-specific 99·5th percentile of the daily precipitation from 1986 to 2005; then we estimated the associations between extreme precipitation events and cause-specific deaths in 280 Chinese counties using a two-stage time-series model. Second, we projected the excess deaths related to extreme precipitation events by combining the bias-corrected multi-model precipitation predictions derived under different combined emission-population scenarios of three representative concentration pathways (RCPs; RCP2·6, RCP4·5, and RCP8·5) and three shared socioeconomic pathways (SSP2, a business-as-usual scenario) populations (S1, low fertility rate; S2, medium fertility rate; and S3, high fertility rate). We quantified the climate and population contributions to the changes of future excess deaths nationwide and by climatic zones.

FINDINGS

Compared with the non-extreme precipitation days, the percentage increase of deaths associated with exposure to extreme precipitation days is 13·0% (95% CI 7·0-19·3) for accidental cause, 4·3% (2·0-6·6) for circulatory disease, and 6·8% (2·8-10·9) for respiratory disease. The number of annual average excess deaths related to extreme precipitation events during 1986-2005 was 2644 (95% CI 1496-3730) for accidental cause, 69 (33-105) for circulatory disease, and 181 (79-279) for respiratory disease. In the 2030s, the total number of excess deaths of these three causes will increase by 1244 (43%), 1756 (61%), and 2008 (69%) under RCP2·6, RCP4·5, and RCP8·5 scenarios combined with a medium-fertility-rate population (SSP2-S2), respectively, but will decrease by 3% under RCP2·6-SSP2-S2 and increase by 25% under RCP8·5-SSP2-S2 in the 2090s. Humid and water-limited regions in subtropical, middle-temperate, and plateau climate zones will face highly increased risks. Climate and population factors contributed disproportionally among the five climate zones.

INTERPRETATION

This study is the largest integrated projection exploring the disease burden associated with extreme precipitation events. The excess deaths will be amplified by climate and population changes. Improving mitigation and adaptation capacities is crucial when responding to precipitation extremes.

FUNDING

National Natural Science Foundation of China and Wellcome Trust.

The Influence of Climate, Atmospheric Pollution, and Natural Disasters on Cardiovascular Diseases and Diabetes Mellitus in Drylands: A Scoping Review

Objectives

In the face of escalating global aridification, this study examines the complex relationship between climate variability, air pollution, natural disasters, and the prevalence of cardiovascular disease (CVD) and diabetes mellitus (DM) in arid regions.

Methods

The study conducted a scoping review of multiple databases using JBI guidelines and included 74 studies.

Results

The results show that acute myocardial infarction (n = 20) and stroke (n = 13) are the primary CVDs affected by these factors, particularly affecting older adults (n = 34) and persons with hypertension (n = 3). Elevated air temperature and heat waves emerge as critical risk factors for CVD, exacerbating various cardiovascular mechanisms. Atmospheric pollutants and natural disasters increase this risk. Indirect effects of disasters amplify risk factors such as socioeconomic vulnerability (n = 4), inadequate medical care (n = 3), stress (n = 3), and poor diet (n = 2), increasing CVD and DM risk.

Conclusion

The study underscores the need for nations to adhere to the Paris Agreement, advocating for reduced air pollutants, resilient environments, and collaborative, multidisciplinary research to develop targeted health interventions to mitigate the adverse effects of climate, pollution, and natural disasters.

Heat and Cardiovascular Mortality: An Epidemiological Perspective

As global temperatures rise, extreme heat events are projected to become more frequent and intense. Extreme heat causes a wide range of health effects, including an overall increase in morbidity and mortality. It is important to note that while there is sufficient epidemiological evidence for heat-related increases in all-cause mortality, evidence on the association between heat and cause-specific deaths such as cardiovascular disease (CVD) mortality (and its more specific causes) is limited, with inconsistent findings. Existing systematic reviews and meta-analyses of epidemiological studies on heat and CVD mortality have summarized the available evidence. However, the target audience of such reviews is mainly limited to the specific field of environmental epidemiology. This overarching perspective aims to provide health professionals with a comprehensive overview of recent epidemiological evidence of how extreme heat is associated with CVD mortality. The rationale behind this broad perspective is that a better understanding of the effect of extreme heat on CVD mortality will help CVD health professionals optimize their plans to adapt to the changes brought about by climate change and heat events. To policymakers, this perspective would help formulate targeted mitigation, strengthen early warning systems, and develop better adaptation strategies. Despite the heterogeneity in evidence worldwide, due in part to different climatic conditions and population dynamics, there is a clear link between heat and CVD mortality. The risk has often been found to be higher in vulnerable subgroups, including older people, people with preexisting conditions, and the socioeconomically deprived. This perspective also highlights the lack of evidence from low- and middle-income countries and focuses on cause-specific CVD deaths. In addition, the perspective highlights the temporal changes in heat-related CVD deaths as well as the interactive effect of heat with other environmental factors and the potential biological pathways. Importantly, these various aspects of epidemiological studies have never been fully investigated and, therefore, the true extent of the impact of heat on CVD deaths remains largely unknown. Furthermore, this perspective also highlights the research gaps in epidemiological studies and the potential solutions to generate more robust evidence on the future consequences of heat on CVD deaths.

A pilot heat-health warning system co-designed for a subtropical city

Significant heat-related casualties underlie the urgency of establishing a heat-health warning system (HHWS). This paper presents an evidence-based pilot HHWS developed for Taipei City, Taiwan, through a co-design process engaging stakeholders. In the co-design process, policy concerns related to biometeorology, epidemiology and public health, and risk communication aspects were identified, with knowledge gaps being filled by subsequent findings. The biometeorological results revealed that Taipei residents were exposed to wet-bulb globe temperature (WBGT) levels of health concern for at least 100 days in 2016. The hot spots and periods identified using WBGT would be missed out if using temperature, underlining the importance of adopting an appropriate heat indicator. Significant increases in heat-related emergency were found in Taipei at WBGT exceeding 36°C with reference-adjusted risk ratio (RaRR) of 2.42, taking 30°C as the reference; and residents aged 0-14 had the highest risk enhancement (RaRR = 7.70). As for risk communication, occurring frequency was evaluated to avoid too frequent warnings, which would numb the public and exhaust resources. After integrating knowledge and reconciling the different preferences and perspectives, the pilot HHWS was co-implemented in 2018 by the science team and Taipei City officials; accompanying responsive measures were formulated for execution by ten city government departments/offices. The results of this pilot served as a useful reference for establishing a nationwide heat-alert app in 2021/2022. The lessons learnt during the interactive co-design processes provide valuable insights for establishing HHWSs worldwide.

China's public health initiatives for climate change adaptation

China's health gains over the past decades face potential reversals if climate change adaptation is not prioritized. China's temperature rise surpasses the global average due to urban heat islands and ecological changes, and demands urgent actions to safeguard public health. Effective adaptation need to consider China's urbanization trends, underlying non-communicable diseases, an aging population, and future pandemic threats. Climate change adaptation initiatives and strategies include urban green space, healthy indoor environments, spatial planning for cities, advance location-specific early warning systems for extreme weather events, and a holistic approach for linking carbon neutrality to health co-benefits. Innovation and technology uptake is a crucial opportunity. China's successful climate adaptation can foster international collaboration regionally and beyond.

The 2022 Summer record-breaking heatwave and health information-seeking behaviours: an infodemiology study in Mainland China

INTRODUCTION

Heatwave is a major global health concern. Many countries including China suffered a record-breaking heatwave during the summer of 2022, which may have a significant effect on population health or health information-seeking behaviours but is yet to be examined.

METHODS

We derived health information-seeking data from the Baidu search engine (similar to Google search engine). The data included city-specific daily search queries (also referred to Baidu Search Index) for heat-sensitive diseases from 2021 to 2022, including heatstroke, hospital visits, cardiovascular diseases and diabetes, respiratory diseases, mental health and urological diseases. For each city, the record-breaking heatwave days in 2022 were matched to days in the same calendar month in 2021.

RESULTS

The 2022 record-breaking heatwave hit most cities (83.64%) in Mainland China. The average heatwave duration was 13 days and the maximum temperature was 3.60°C higher than that in 2021 (p<0.05). We observed increased population behaviours of seeking information on respiratory diseases (RR=1.014, 95% CI: 1.008 to 1.020), urological diseases (RR=1.011, 95% CI: 1.006 to 1.016) and heatstroke (RR=1.026, 95% CI: 1.016 to 1.036) associated with the heatwave intensity in 2022 (per 1°C increase). The heatwave duration in 2022 (per 1 day increase) was also associated with an increase in seeking information on cardiovascular diseases and diabetes (RR=1.003, 95% CI: 1.002 to 1.004), urological diseases (RR=1.005, 95% CI: 1.002 to 1.008), mental health (RR=1.009, 95% CI: 1.006 to 1.012) and heatstroke (RR=1.038, 95% CI: 1.032 to 1.043). However, there were substantial geographical variations in the effect of the 2022 heatwave intensity and duration on health information-seeking behaviours.

CONCLUSION

This infodemiology study suggests that the 2022 summer unprecedented heatwave in Mainland China has significantly increased population demand for health-related information, especially for heatstroke, urological diseases and mental health. Population-based research of real-time disease data is urgently needed to estimate the negative health impact of the exceptional heatwave in Mainland China and elsewhere.

The Scorching Truth: Investigating the Impact of Heatwaves on Selangor's Elderly Hospitalisations

Global climate change has contributed to the intensity, frequency, and duration of heatwave events. The association between heatwaves and elderly mortality is highly researched in developed countries. In contrast, heatwave impact on hospital admissions has been insufficiently studied worldwide due to data availability and sensitivity. In our opinion, the relationship between heatwaves and hospital admissions is worthwhile to explore as it could have a profound impact on healthcare systems. Therefore, we aimed to investigate the associations between heatwaves and hospitalisations for the elderly by age group in Selangor, Malaysia, from 2010 to 2020. We further explored the impact of heatwaves on the risks of cause-specific hospital admissions across age groups within the elderly. This study applied generalized additive models (GAMs) with the Poisson family and distributed lag models (DLMs) to estimate the effect of heatwaves on hospitalisations. According to the findings, there was no significant increase in hospitalisations for those aged 60 and older during heatwaves; however, a rise in mean apparent temperature (ATmean) by 1 °C significantly increased the risk of hospital admission by 12.9%. Heatwaves had no immediate effects on hospital admissions among elderly patients, but significant delay effects were identified for ATmean with a lag of 0-3 days. The hospital admission rates of the elderly groups started declining after a 5-day average following the heatwave event. Females were found to be relatively more vulnerable than males during heatwave periods. Consequently, these results can provide a reference to improve public health strategies to target elderly people who are at the greatest risk of hospitalisations due to heatwaves. Development of early heatwave and health warning systems for the elderly would assist with preventing and reducing health risks while also minimising the burden on the whole hospital system in Selangor, Malaysia.