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

Population aging exacerbates heat stroke-related ambulance transportations in Japan

Rapid aging significantly increases Japan's population vulnerability to severe heat stress, yet the precise impact on heat stroke-related morbidity remains unclear. This study integrates multiple datasets and develops predictive models for daily heat stroke-related emergency ambulance dispatches (HT-EADs) among younger and older populations in Japan for 2010-2019. By adjusting the proportion of older adults and incorporating pseudo climate warming, we assessed how aging and warming could amplify total HT-EADs. Compared to the simulation using demographic conditions of 1995, recent aging trends have led to a 15% increase in total HT-EADs in Japan during 2010-2019, an effect equivalent to a 0.3℃ warming. This increase could rise to 30% under a super-aging demographic scenario by 2045, surpassing the impact of a 0.5℃ warming. Our findings emphasize that aging has comparable negative impacts on heat stroke morbidity as climate change, highlighting the urgent need of enhanced protections for older residents during hot summers.

Dietary Nucleotides Enhance Neurogenesis, Cognitive Capacity, Muscle Function, and Body Composition in Older Adults: A Randomized, Triple-Blind, Controlled Clinical Trial

BACKGROUND/OBJECTIVES

this study evaluated the differential effects of two distinct dietary nucleotide supplements, combined with spontaneous physical activity, on neuromuscular, cognitive, and metabolic adaptations in older adults.

METHODS

Sixty-nine physically independent older adults (aged 60-75 years) were randomly assigned to three groups: (1) a yeast nucleotides formulation (YN) standardized in a high content of free nucleotides (>40%) rich in all macro and micro nutrients naturally occurring in yeast cell (amino acids, minerals and B-group vitamin); (2) a neuro-based formulation (NF) consisting of a blend of monophosphate nucleotides 5'; or (3) a placebo. Participants maintained their spontaneous physical activities without structured exercise during a 10-week intervention. Assessments included physical function, cognitive performance, body composition, quality of life, and serum biomarkers of oxidative stress, inflammation, and neurogenesis.

RESULTS

Both nucleotide-supplemented groups demonstrated significant improvements compared to placebo in physical performance (p ≤ 0.045), cognitive function (Trail Making Test B [TMT-B]: p ≤ 0.012), oxidative stress biomarkers (p ≤ 0.048), inflammatory cytokines (p ≤ 0.023), and quality-of-life parameters (p ≤ 0.047). Body composition remained stable in supplemented groups, whereas placebo increased fat mass (5.04%) and decreased muscle mass (-2.18%).

CONCLUSIONS

Dietary nucleotide supplementation enhances the benefits of spontaneous physical activity across all measured variables in older adults, highlighting nucleotides as promising nutritional support for healthy aging. YN exhibited a trend toward greater inflammatory modulation, whereas NF showed a tendency toward enhanced neurotrophic effects and functional improvements, with a statistically significant improvement in the Timed Up and Go Test (p = 0.014). These findings underscore the potential for tailored nucleotide-based interventions to optimize distinct physiological domains in aging populations.

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.

Framework for Environmentally Sustainable Radiology: Call for Collaborative Action and a Health-Centered Focus

"Just Accepted" papers have undergone full peer review and have been accepted for publication in Radiology. This article will undergo copyediting, layout, and proof review before it is published in its final version. Please note that during production of the final copyedited article, errors may be discovered which could affect the content. It is imperative that the entire medical imaging sector acts collectively and decisively to reduce its own environmental impact and prepare for the current and future effects of the climate crisis. The Radiology R7 meeting convened in Venice, Italy, on October 10-13, 2024 to discuss environmental sustainability and other key issues facing radiology and the patients served by medical imaging. Radiology R7 delegates agree that collaborative action is urgently needed to transform radiology systems to be climate-resilient, equitable, low-carbon, and sustainable. This special report highlights priorities and outlines a framework for environmentally sustainable radiology, centered on eight collaborative action areas. A health-centered response reinforces the role of radiologists as physicians, emphasizes the opportunity for medical imaging to improve health, and will be essential to engage key partners in climate action. Effective leadership and governance are needed to ensure that radiology services are accessible, equitable, affordable, high quality and sustainable. Collaboration and partnership are essential to achieve meaningful change. Health equity should be prioritized to increase global access to high quality radiology services while minimizing the environmental impact. Multiple climate response pathways should be implemented in parallel including mitigation strategies to reduce the use of energy, finite resources and waste and adaptation strategies to build resilience to the effects of climate change. Innovation and research are necessary to develop, validate, and implement sustainable solutions. Finally, knowledge sharing, education, and training are needed to disseminate information on actions toward environmentally sustainable radiology practices. We all have a role to play and must work together to achieve these aims quickly by identifying the problem, setting goals, implementing a plan, measuring impact, sharing results, and celebrating successes.

Cold and longevity: Can cold exposure counteract aging?

Aging is a multifaceted biological process characterized by a progressive decline in physiological functions and heightened vulnerability to diseases, shaped by genetic, environmental, and lifestyle factors. Among these, cold exposure has garnered interest for its potential anti-aging benefits. This review examines the impact of cold exposure on aging, focusing on key physiological processes such as inflammation, oxidative stress, metabolic regulation, and cardiovascular health. Cold exposure has been shown to reduce chronic inflammation, enhance antioxidant defenses, and improve metabolic health by activating brown adipose tissue. Furthermore, findings from hibernating mammals and model organisms suggest a connection between lower environmental temperatures and increased longevity. However, the potential long-term health risks of extended cold exposure, particularly in older adults, remain a significant concern. Epidemiological studies reveal increased rates of mortality and morbidity in populations living in cold climates, emphasizing the complexity of the relationship between cold exposure and aging. This review underscores the need for further research to elucidate the long-term effects of cold exposure on aging and to establish guidelines for leveraging its benefits while mitigating cold-induced risks.

Human-Centric, Three Dimensional Micro Light-Emitting Diodes for Cosmetic and Medical Phototherapy

Phototherapy based on micro light-emitting diodes (µLEDs) has gained enormous attention in the medical field as a patient-friendly therapeutic method due to its advantages of minimal invasiveness, fewer side effects, and versatile device form factors with high stability in biological environment. Effective cosmetic and medical phototherapy depends on deep light penetration, precise irradiation, and simultaneous multi-site stimulation, facilitated by three-dimensional (3D) optoelectronics specifically designed for complex human matters, defined here as 3D µLEDs. This perspective article aims to present the functionalities and strategies of 3D µLEDs for human-centric phototherapy. This study investigates the effectiveness of phototherapy enabled by three key functionalities such as shape morphing, self-adaptation, and multilayered spatiotemporal mapping of 3D µLEDs. Finally, this article provides future insights of 3D µLEDs for human-centric phototherapy applications.

Cold-Related Deaths in the US

This study examines trends in cold-related mortality overall and by demographic characteristics between 1999 and 2022 in the US.

Short-term effects of combined environmental factors on respiratory disease mortality in Qingdao city: A time-series investigation

BACKGROUND

It is crucial to comprehend the interplay between air pollution and meteorological conditions in relation to population health within the framework of "dual-carbon" targets. The purpose of this study was to investigate the impact of intricate environmental factors, encompassing both meteorological conditions and atmospheric pollutants, on respiratory disease (RD) mortality in Qingdao, a representative coastal city in China.

METHODS

The RD mortality cases were collected from the Chronic Disease Surveillance Monitoring System in Qingdao during Jan 1st, 2014 and Dec 31st, 2020. The distributed-lag nonlinear model and generalized additivity model were used to assess the association between daily mean temperature (DMT), air pollutant exposure and RD mortality. To ascertain the robustness of the model and further investigate this relationship, a stratified analysis and sensitivity analysis were conducted to mitigate potential confounding factors.

RESULTS

A total of 19,905 mortalities from RD were recorded. The minimum mortality temperature (MMT) was determined to be 23.5°C, and DMT and RD mortality showed an N-shaped relationship. At the MMT of 23.5°C, the cumulative relative risk (cumRR) for mortality within a lag period of 0-14 days from the highest temperature (31°C) was estimated at 2.114 (95% confidence interval [CI]: 1.475 ~ 3.028). The effect value of particulate matter (PM) also increased with a longer cumulative lag time. In the single pollutant model, the highest risk of RD mortality was observed on the lag1-day of per 10 μg/m3 increase in PM2.5 exposure, with an excess risk ratio (ER) of 0.847% (95% CI: 0.335% ~ 1.362%). The largest cumulative effect was found at a lag of 8 days, with an ER of 1.546% (95% CI: 0.483% ~ 2.621%). A similar trend was found for PM10. For O3 exposure, the highest risk was observed on the lag1-day of per 10 μg/m3 increase, with an ER of 1.073% (95% CI: 0.502% ~ 1.647%), and the largest cumulative effect occurred at a lag of 2 days with an ER of 1.113% (95%CI: 0.386% ~ 1.844%). Results from the dual-pollutants model demonstrated that the effect of PM on the risk of RD mortality remained significant and slightly increased in magnitude. Moreover, composite pollutants exhibited a higher risk effect, reaching its peak after one week; however, there was a decrease in single-day cumulative effects as more pollutant types were included. Subgroup analysis showed that females, elderly individuals, and those exposed during warm seasons demonstrated greater susceptibility to PM exposure.

CONCLUSION

The present study revealed a significant association between short-term exposure to high temperature, PM2.5, PM10 and O3 and the risk of RD mortality in Qingdao, even in dual- and composite-pollutants models. Furthermore, our findings indicate that females, the elderly population, and warm seasons exhibit heightened sensitivity to PM exposure.

Exceeding the limits of paediatric heat stress tolerance: the risk of losing a generation to climate inaction

Greenhouse gas (GHG) emissions are creating unprecedented climate-driven extreme weather, with levels of heat and humidity surpassing human physiological tolerance for heat stress. These conditions create a risk of mass casualties, with some populations particularly vulnerable due to physiological, behavioural and socioeconomic conditions (eg, lack of adequate shelter, limited healthcare infrastructure, sparse air conditioning access and electrical grid vulnerabilities). Children, especially young children, are uniquely vulnerable to extreme heat-related morbidity and mortality due to factors including low body mass, high metabolism, suboptimal thermoregulatory mechanisms and behavioural vulnerabilities. Children are also uniquely vulnerable to non-fatal heat-related morbidities, including malnutrition due to agricultural disruptions and cardiometabolic, respiratory and mental illnesses from heat exposure and/or confinement during heat avoidance. Climate mitigation through GHG reductions is central to reducing harms to children and preventing the loss of a generation to climate change. In regions most predisposed to extreme heat-driven mass casualties under various GHG emission scenarios-particularly South Asian and Southwest Asian and North African regions-adaptation tools specific to children's needs are the most urgently needed. Existing public health interventions (eg, cooling infrastructure and preventative educational campaigns) to reduce acute heat mortality, and medical infrastructure capacity to treat heat-related illnesses are currently inadequate to meet children's growing heat resiliency needs. Paediatricians and other clinical and community child healthcare providers in these regions lack education about children's heat risks and adaptation tools. Paediatricians and other child healthcare providers have a crucial role in research, education, clinical practice and advocacy to protect children during extreme heat events. Paediatricians, other child healthcare providers and stakeholders of children's well-being are urged to act on young children's behalf and to elevate youth leadership in GHG mitigation and extreme heat adaptation policy-making.

Factors, mechanisms and improvement methods of muscle strength loss

Muscle strength is a crucial aspect of muscle function, essential for maintaining normal physical activity and quality of life. The global aging population coupled with the increasing prevalence of muscle disorders and strength loss, poses a remarkable public health challenge. Understanding the mechanisms behind muscle strength decline is vital for improving public health outcomes. This review discusses recent research advancements on muscle strength loss from various perspectives, including factors contributing to muscle strength decline, the signaling pathways involved in the deterioration of muscle function, and the methods for assessing muscle strength. The final section explores the influence of exercise stimulation and nutrition on muscle strength.

Impact of Extreme Heat on Cardiovascular Health in Kuwait: Present and Future Projections

BACKGROUND

The Middle East, especially Kuwait, is experiencing rapidly rising temperatures due to climate change. Cardiovascular diseases (CVD) are the leading cause of mortality in the country, and extreme heat is expected to exacerbate hospitalizations for cardiovascular diseases. There is limited data quantifying the historical and future impacts of heat on hospitalizations for cardiovascular diseases in Kuwait.

METHODS

We collected daily hospital admission data of cardiovascular diseases in Kuwait from 2010 to 2019. We modeled the relationship between temperature and cardiovascular disease hospitalizations using distributed lag non-linear models (DLNMs), adjusting for relative humidity and seasonality. Future temperature projections for Kuwait under moderate and extreme climate change scenarios were obtained from the Coupled Model Inter-comparison Project Phase 6 (CMIP6), and the impact on cardiovascular disease hospitalizations was extrapolated for every decade until 2099.

RESULTS

During the baseline period (2010-2019), a total of 263,182 CVD cases were recorded. Of which, 20,569 (95% eCI: 3,128, 35,757) were attributed to heat. We found that the relative risk of hospitalization for CVD increased from 1.292 (95% CI: 1.051, 1.589) at 41 °C to 1.326 (95% CI: 1.006, 1.747) at 43 °C, compared to the minimum morbidity temperature. Projections showed that, under moderate climate scenarios, CVD hospitalizations would increase by 1.96% by 2090-2099, while under extreme scenarios, the increase could reach 4.44%.

CONCLUSIONS

Extreme heat significantly contributes to CVD hospitalizations in Kuwait. This burden is projected to increase under climate change. Findings highlight the urgent need for healthcare system preparedness to mitigate the future health impacts of rising temperatures in Kuwait.

The Impact of Global Warming on the Rise in Heat-Related Illnesses in Emergency Medical Services

PURPOSE

Global warming is one of the critical problems affecting health, society, and the economy. High temperatures are linked to an increase in heat-related illnesses, which have significantly impacted the public health system, particularly emergency medical services (EMS). Analyzing the pattern of heat-related illness cases in EMS can improve resource utilization and preparedness within the public health system.

PATIENTS AND METHODS

A retrospective study was conducted on EMS data from Srinagarind Hospital, Thailand, covering the summer months (February to May) from 2020 to 2024. Patients with heat-related illnesses were identified in the EMS database using the 10th revision of the International Classification of Diseases (ICD-10) version 2019, specifically codes under "T67 Effects of Heat and Light", which include heat stroke, heat syncope, heat cramps, heat exhaustion, and heat fatigue.

RESULTS

A total of 136 EMS operations from the hospital's database were analyzed. In the summer 2024 group, 95.7% (N=44) of the patients were male. The majority of EMS triage cases required resuscitation (P = 0.020). Outdoor activity was identified as a significant factor related to heat illness, with rates of 83.3%, 92.9%, 93.3%, 97.1%, and 93.5% over the five years of the study. The activation time was 1.30 minutes for the summer of 2024 and 1.24 minutes for the summer of 2023. Notably, the average scene time in the summer 2024 group was significantly longer at 25.2 minutes, compared to 12.0 minutes in the summer 2020 group (P<0.001).

CONCLUSION

Outdoor activity was the most significant risk factor associated with increased heat-related illnesses. Other contributing factors included male gender, age between 20-40 years, scene temperatures above 35°C, and prolonged scene times exceeding 15 minutes.

Effect of black soldier fly larvae frass addition on humus content during low temperature co-composting

Initiating aerobic fermentation under low temperature is the main challenge for winter livestock manure composting. This study aims to address this issue by applying black soldier fly larvae (BSFL) frass as a co-composting additive to enhance the low-temperature composting process. Specifically, this work explored the effects of chicken manure and BSFL frass co-composting on the temperature, humus content, and microorganisms with fresh weight ratio of 2:1, 1:1, 1:2 (w/w) at 6 °C. The result showed frass could rapidly rise the temperature to 50 °C and significantly increased the humus content by 15.6 % ∼ 26.3 %. Moreover, microbial analysis revealed that Sphingobacteriaceae accelerated temperature rise via low-temperature reproduction, creating proper temperature for thermophilic bacteria (Truepera and Georgia). Additionally, Cellulomonas and other bacteria promoted organic matter degradation and participated in humus formation. This study presents a novel solution for low-temperature composting, providing practical insights for improving manure management in winter.

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.

Challenges posed by climate hazards to cardiovascular health and cardiac intensive care: implications for mitigation and adaptation

Global warming, driven by increased greenhouse gas emissions, has led to unprecedented extreme weather events, contributing to higher morbidity and mortality rates from a variety of health conditions, including cardiovascular disease (CVD). The disruption of multiple planetary boundaries has increased the probability of connected, cascading, and catastrophic disasters with magnified health impacts on vulnerable populations. While the impact of climate change can be manifold, non-optimal air temperatures (NOTs) pose significant health risks from cardiovascular events. Vulnerable populations, especially those with pre-existing CVD, face increased risks of acute cardiovascular events during NOT. Factors such as age, socio-economic status, minority populations, and environmental conditions (especially air pollution) amplify these risks. With rising global surface temperatures, the frequency and intensity of heatwaves and cold spells are expected to increase, emphasizing the need to address their health impacts. The World Health Organization recommends implementing heat-health action plans, which include early warning systems, public education on recognizing heat-related symptoms, and guidelines for adjusting medications during heatwaves. Additionally, intensive care units must be prepared to handle increased patient loads and the specific challenges posed by extreme heat. Comprehensive and proactive adaptation and mitigation strategies with health as a primary consideration and measures to enhance resilience are essential to protect vulnerable populations and reduce the health burden associated with NOTs. The current educational review will explore the impact on cardiovascular events, future health projections, pathophysiology, drug interactions, and intensive care challenges and recommend actions for effective patient care.

Integrating social, climate and environmental changes to confront accelerating global aging

INTRODUCTION

The global increase in the aging population presents critical challenges for healthcare systems, social security, and economic stability worldwide. Although the studies of the global rate of aging have increased more than four times in the past two decades, few studies have integrated the potential combined effects of socio-economic, climatic, and environmental factors.

METHODS

We calculated the geographic heterogeneity of aging population growth rates from 218 countries between 1960 and 2022. Public databases were then integrated to assess the impacts of seven global stressors: socio-economic vulnerability, temperature, drought, seasonality, climate extremes, air pollution, and greening vulnerability on growth rates of aging population (a totally 156 countries). Linear regression models were primarily used to test the statistically significant effects of these stressors on the rate of aging, and multiple model inference was then used to test whether the number of stressors exceeding specific thresholds (e.g., > 25, 50, and 75%) was consistently significant in the best models. The importance of stressors and the number of stressors exceeding thresholds was verified using random forest models for countries experiencing different population aging rates.

RESULTS

Our analysis identified significant heterogeneity in growth rates of aging population globally, with many African countries exhibiting significantly lower aging rates compared with Europe. High socio-economic vulnerability, increased climate risks (such as high temperature and intensive extreme climate), and decreased environmental quality were found to significantly increase growth rates of the aging population (P < 0.05). The positive combined impacts of these stressors were diminished at medium-high levels of stressors (i.e., relative to their maximum levels observed in nature). The number of global stressors exceeding the 25% threshold emerged as an important predictor of global aging rates. Demographic changes in regions with relatively rapid aging (e.g., Africa and Asia) are more sensitive to climate change (e.g., extreme climate and drought) and the number of global stressors, and regions with low to medium rates of aging (e.g., Europe and the Americas) are more sensitive to socio-economic vulnerability and environmental stability (e.g., drought, green fragility and air pollution).

CONCLUSIONS

Our findings underscore that policy tools or methods must be developed that consider the holistic dimension of the global factor. Further investigations are essential to understand the complex interactions between multiple stressors and their combined effects on global aging.

Future temperature-related mortality in the UK under climate change scenarios: Impact of population ageing and bias-corrected climate projections

BACKGROUND

Exposure to heat and cold poses a serious threat to human health. In the UK, hotter summers, milder winters and an ageing population will shift how populations experience temperature-related health burdens. Estimating future burdens can provide insights on the drivers of temperature-related health effects and removing biases in temperature projections is an essential step to generating these estimates, however, the impact of various methods of correction is not well examined.

METHODS

We conducted a detailed health impact assessment by estimating mortality attributable to temperature at a baseline period (2007-2018) and in future decades (2030s, 2050s and 2070s). Epidemiological exposure-response relationships were derived for all England regions and UK countries, to quantify cold and heat risk, and temperature thresholds where mortality increases. UK climate projections 2018 (UKCP18)were bias-corrected using three techniques: correcting for mean bias (shift or SH), variability (bias-correction or BC) and extreme values (quantile mapping or QM). These were applied in the health impact assessment, alongside consideration of population ageing and growth to estimate future temperature-related mortality.

FINDINGS

In the absence of adaptation and assuming a high-end emissions scenario (RCP8.5), annual UK temperature-related mortality is projected to increase, with substantial differences in raw vs. calibrated projections for heat-related mortality, but smaller differences for cold-related mortality. The BC approach gave an estimated 29 deaths per 100,000 in the 2070s, compared with 50 per 100,000 using uncorrected future temperatures. We also found population ageing may exert a bigger impact on future mortality totals than the impact from future increases in temperature alone. Estimating future health burdens associated with heat and cold is an important step towards equipping decision-makers to deliver suitable care to the changing population. Correcting inherent biases in temperature projections can improve the accuracy of projected health burdens to support health protection measures and long-term resilience planning.

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.

Development of a Method to Determine the Environmental Burden of Diseases and an Application to Identify Factors Driving Changes in the Number of PM2.5-Related Deaths in China between 2000 and 2010

The attributable burden is codetermined by the exposure level and nontarget characteristics. However, the conventional method of health impact assessment based on preestablished exposure-response functions includes only a few well-known characteristics and thus is insufficient to capture the comprehensive variation. We aimed to develop a method to fuse health impact assessment with epidemiological analysis and to identify factors driving baseline risk. The method was applied to identify the factors underlying the change in the number of fine particulate matter (PM2.5) related deaths in China between 2000 and 2010. During the study period, the number of PM2.5-related deaths across mainland China increased by 0.62 (95% CI: 0.57, 0.69) million, with 0.65 (95% CI: 0.47, 0.91) million, 0.55 (95% CI: 0.39, 0.79) million, and 0.11 (95% CI: 0.06, 0.18) million deaths being associated with increased PM2.5 exposure, population aging, and growth in population size, respectively. However, economic growth, urbanization, improvement of welfare services, and improvement of hospital services resulted in 0.25 (95% CI: 0.15, 0.40) million, 0.16 (95% CI: 0.10, 0.27) million, 0.16 (95% CI: 0.09, 0.26) million, and 0.09 (95% CI: 0.05, 0.15) million fewer deaths, respectively. Results indicated that increased exposure was the major driver of the change in the number of PM2.5-related deaths, and economic growth was the main driver of increased resilience to air pollution.

Temporal trends in temperature-related mortality and evidence for maladaptation to heat and cold in the Eastern Mediterranean region

The eastern Mediterranean region is characterized by rising temperature trends exceeding the corresponding global averages and is considered a climate change hot-spot. Although previous studies have thoroughly investigated the impact of extreme heat and cold on human mortality and morbidity, both for the current and future climate change scenarios, the temporal trends in temperature-related mortality or the potential historical adaptation to heat and cold extremes has never been studied in this region. This study focuses on cardiovascular mortality and assesses the temporal evolution of the Minimum Mortality Temperature (MMT), as well as the disease-specific cold- and heat-attributable fraction of mortality in three typical eastern Mediterranean environments (Athens, Thessaloniki and Cyprus). Data on daily cardiovascular mortality (ICD-10 code: I00-I99) and meteorological parameters were available between 1999 and 2019 for Athens, 1999 to 2018 for Thessaloniki and 2004 to 2019 for Cyprus. Estimation of cardiovascular MMT and mortality fractions relied on time-series Poisson regressions with distributed lag nonlinear models (DLNM) controlling for seasonal and long-term trends, performed over a series of rolling sub-periods at each site. The results indicated that in Athens, the MMT decreased from 23 °C (67.5th percentile) in 1999-2007 to 21.8 °C (62nd percentile) in 2011-2019, while in Cyprus the MMT decreased from 26.3 °C (79th percentile) in 2004-2012 to 23.9 °C (66.5th percentile) in 2011-2019. In Thessaloniki, the decrease in MMT was rather negligible. In all regions under study, the fractions of mortality attributed to both cold and heat followed an upward trend throughout the years. In conclusion, the demonstrated increase in cold attributable fraction and the decreasing temporal trend of MMT across the examined sites are suggestive of maladaptation to extreme temperatures in regions with warm climate and highlight the need for relevant public health policies and interventions.

Heat, humidity and health impacts: how causal diagrams can help tell the complex story

The global health burden associated with exposure to heat is a grave concern and is projected to further increase under climate change. While physiological studies have demonstrated the role of humidity alongside temperature in exacerbating heat stress for humans, epidemiological findings remain conflicted. Understanding the intricate relationships between heat, humidity, and health outcomes is crucial to inform adaptation and drive increased global climate change mitigation efforts. This article introduces 'directed acyclic graphs' (DAGs) as causal models to elucidate the analytical complexity in observational epidemiological studies that focus on humid-heat-related health impacts. DAGs are employed to delineate implicit assumptions often overlooked in such studies, depicting humidity as a confounder, mediator, or an effect modifier. We also discuss complexities arising from using composite indices, such as wet-bulb temperature. DAGs representing the health impacts associated with wet-bulb temperature help to understand the limitations in separating the individual effect of humidity from the perceived effect of wet-bulb temperature on health. General examples for regression models corresponding to each of the causal assumptions are also discussed. Our goal is not to prioritize one causal model but to discuss the causal models suitable for representing humid-heat health impacts and highlight the implications of selecting one model over another. We anticipate that the article will pave the way for future quantitative studies on the topic and motivate researchers to explicitly characterize the assumptions underlying their models with DAGs, facilitating accurate interpretations of the findings. This methodology is applicable to similarly complex compound events.

Analyzing temperature, humidity, and precipitation trends in six regions of Thailand using innovative trend analysis

The change of temperature and weather parameters is a major concern affecting sustainable development and impacting various sectors, such as agriculture, tourism, and industry. Changing weather patterns and their impact on water resources are important climatic factors that society is facing. In Thailand, climatological features such as ambient temperature, relative humidity, and precipitation play a substantial role in affecting extreme weather events, which cause damage to the economy, agriculture, tourism, and livelihood of people. To investigate recent serious changes in annual trends of temperature, relative humidity, and precipitation in Thailand, this study used the Mann-Kendall (MK) test and innovative trend analysis (ITA) methods. The MK test showed that all six regions had an upward trend in temperature and humidity index (humidex, how hot the weather feels to the average person), while relative humidity and precipitation showed both upward and downward trends across different regions. The ITA method further confirmed the upward trend in temperature and humidex and showed that most data points fell above the 1:1 line. However, the upward trend in most variables was not significant at the 5% level. The southern and eastern regions showed a significant upward trend in relative humidity and humidex at a 5% level of significance according to the MK test. The output of this study can help in the understanding of weather variations and predict future situations and can be used for adaptation strategies.