Association between high temperature and heatwaves with heat-related illnesses: A systematic review and meta-analysis

Extreme heat and hospital admissions in older adults: A small-area analysis in the Greater Boston metropolitan area

Extreme heat (EH) is a leading cause of weather-related fatalities in the United States. In Massachusetts, average temperatures have increased by 1.9 °C since the 20th century, higher than the global average increase of 1.1 °C. EH disproportionately impacts communities, exacerbating social inequities. This study examined the risks of heat-related hospitalizations in each small area of the Greater Boston Metropolitan Area using Medicare data (2000-2016). EH events included daily heat index (HI), days with an HI above the 90th percentile, and heat waves (≥2 consecutive EH days). We applied a case-crossover design to estimate area-specific associations between EH and hospitalizations and assessed effect modifications by an individual (age ≥85, sex, Medicaid dual eligibility) and ZIP-code characteristics (green space, poverty, educational attainment, and household income). Results were pooled using random effects meta-analysis. Area-specific analysis revealed higher hospitalization risks in Boston compared with surrounding areas. Pooled results indicated heat-related hospitalizations increased by 9.0% (95% CI = 5.7, 12.3) per 10 °C rise in HI, 14.4% (95% CI = 8.8, 20.3) on EH days, and 17.9% (95% CI = 11.1, 25.1) during heat waves. Risks were more pronounced in Boston, and some indications of elevated risk among males and residents in low-income, low-education areas. These findings underscore that heat-related health risks may be different across the level of geographic units and suggest the need for targeted public health strategies to mitigate the impacts of EH.

Heat in the transport sector: measured heat exposure and interventions to address heat-related health impacts in the minibus taxi industry in South Africa

High temperatures, heat and heatwaves are being experienced more frequently and with greater intensity in many parts of the world, including South Africa, and record-breaking maximum temperatures are becoming more common. Exposure to heat has adverse impacts on human health and wellbeing. The transport sector and its users are vulnerable to heat both inside vehicles as well as in places where people wait for public transport. We sought to assess the temperatures experienced in minibus taxis, a common mode of transport in South Africa and in minibus taxi ranks as well as the heat-related perceptions of minibus taxi drivers working in the Chesterville Taxi Association in Durban. We also observed heat-related elements in minibus taxi ranks. Data from temperature loggers showed that temperatures inside minibus taxis reached up to 39 °C and were between 3-4 °C warmer than outdoors. For around 11 h every day, temperatures inside minibus taxis were warmer than 27 °C - the temperature that is linked to heat-health symptoms. Taxi drivers (N = 16) all agreed they feel hot in the minibus taxi and more than 90% said they drink water to try to cool down. Taxi ranks were lacking in supply of drinking water and shade for minibus taxis and seating. With the projected increase in temperatures caused by climate change, it is imperative to co-develop mitigation and adaptation strategies to minimise heat-related human health impacts in minibus taxis and taxi ranks especially in low- and middle-income countries.

Edaravone's reno-protective effects against chronic heat-stress exposure

Edaravone (EDV) is a potent antioxidant with anti-inflammatory properties. It is used to treat various diseases, especially neurodegenerative diseases. This study aims to examine EDV's potential renal protective effects on kidney injury induced by heat stress in rats. Male Wistar rats were segregated into four distinct groups (n = 16/group): control (Ctr), heat stress (HS), edaravone (EDV), and HS+EDV groups. Heat stress was applied 6 days a week for 30 min for 8 weeks, and EDV treatment (6 mg/kg. IP) was administered simultaneously in the HS+EDV group. After the experiment, blood and kidney tissue samples were gathered for subsequent analysis. Compared to the control group, the HS group exhibited a significant increase in serum creatinine and urea levels (P < 0.05). Additionally, malondialdehyde level and catalase activity, tumor necrosis factor-α (TNF-α), and interleukin-1 beta (IL-1β) mRNA expression were increased in the kidney tissue during HS. The renal tissues of the heat-stressed animal showed noticeable histological alterations compared to the control group. However, in the HS+EDV and EDV groups, the creatinine and urea concentrations in the blood were markedly reduced compared to the HS group (P < 0.05). In addition, renal oxidative stress biomarkers were normalized (malondialdehyde levels and catalase activity; P < 0.05). The histopathological alterations in the renal tissues of the groups treated with EDV were markedly diminished. In addition, the renal mRNA expression levels of IL-1β and TNF-α were markedly reduced in the HS+EDV group compared to the HS group (P < 0.05). EDV treatment in a heat-stress rat model demonstrated a protective effect on renal tissue, most likely due to its antioxidant and anti-inflammatory properties.

Community-based heat adaptation interventions for improving heat literacy, behaviours, and health outcomes: a systematic review

Anthropogenic climate change, resulting in a continuous rise of global temperature, has detrimental effects on human health, particularly among vulnerable populations, such as individuals with low income, older adults, and people with pre-existing health conditions. To reduce the heat-related health consequences, effective interventions targeting community members, especially vulnerable populations, are paramount. This systematic review aims to identify and evaluate the effectiveness of community-based heat adaptation behavioural interventions aimed at improving heat literacy, promoting adaptive behaviours, and enhancing health outcomes amid rising global temperatures. In this systematic review, peer-reviewed English-language articles focused on community-based heat adaptation intervention studies published in PubMed, MEDLINE via Ovid, Embase, CINAHL, Scopus, and Web of Science from database inception to Jan 1, 2024, were retrieved and reported according to the PRISMA 2020 guidelines. The quality of the articles was evaluated with the use of a mixed-methods appraisal tool. The analysis synthesised intervention effectiveness across multiple outcome domains measurable at both individual and household levels, identified key factors influencing successful implementation, and highlighted areas for future research. The initial search yielded 1266 articles, of which ten were finally included. The majority of the included studies (n=7) were from high-income countries. Most intervention modules focused on preventive measures during heat exposure, whereas only a few addressed information on disease mechanisms, risk factors, and monitoring environmental changes. Although most studies reported significant improvements in heat literacy and a reduction in heat-related symptoms, the evidence for behavioural changes and health outcomes was mixed. Our review reveals methodological shortcomings, as none of the included studies incorporated heat literacy frameworks, behavioural theory, or participatory approaches to include community input throughout the research. Our findings highlight the need for a comprehensive approach that incorporates frameworks to enhance intervention effectiveness and improve public health resilience amid rising global temperatures. Culturally appropriate community-led interventions and integration of digital tools are promising avenues for increasing uptake of interventions. This study is registered with PROSPERO (CRD42024514188).

Secular trends in heat related illness and excess sun exposure rates across climatic zones in the United States from 2017 to 2022

Heat waves are a major public health challenge, yet the link between heat-related illness (HRI) and regional climate and geography is underexplored. We examined HRI and excess sun exposure incidence rates (IR) [95% confidence interval (CI) per 100,000 person-years], and their correlation with regional maximum temperatures across 9 US climatic zones 33,603,572 individuals were followed from 2017 to 2022. We observed 10,652 individuals with HRI diagnosis (median age: 49 years, 62.3% male). Seasonal peaks occurred during summer: highest overall IR (130.97 [119.93-142.75]) was recorded in July 2019, highest regional IR was reported in the South (186.04 [117.93-279.15]) during 2020. Strongest correlations between monthly maximum temperature and incidence of HRI were observed in the West (Pearson Correlation Coefficient (cor) = 0.854) and Southwest (cor = 0.832). In contrast, we observed 131,204 individuals with excess sun exposure (predominantly older adults [median age: 67 years], 52.3% female, 30% with history of cancer). Overall IR for sun exposure peaked in March 2021 (664.31 [644.84-684.21]) and lacked a consistent seasonal pattern. Sun exposure exhibited weaker correlations with regional temperatures, even in high-temperature regions like the West (cor = 0.305). These data indicate regional variations in HRI. With distinct at-risk groups for HRI and sun exposure, targeted regional interventions may be beneficial, such as heat safety protocols to reduce HRI risk and sun protection campaigns for older adults to mitigate sun exposure risk.

The Heat Is On: Climate Change Implications for Pregnant Women with Sickle Cell Disease

Sickle cell disease (SCD), a serious, chronic blood disorder is the most common genetic blood disease in the United States affecting 100,000 people and disproportionately affecting the African American population. Pregnancy is particularly risky for people with SCD due to higher risk of developing pregnancy-related complications compared with people without the disease. For African American pregnant women with SCD, the risk of maternal morbidity and mortality is up to 10 times higher. Physiological changes during pregnancy increase the risk of vaso-occlusive episodes (VOEs), acute chest syndrome, venous thromboembolic events, and infections. Dehydration increases risk as it triggers sickling of red blood cells, leading to painful VOEs and further increasing the risk of aforementioned complications. Climate change, observed since the mid-20th century, is evidenced by the increasing trend of global temperature, hurricanes, floods, and heat waves. Climate changes can profoundly impact people with SCD, as elevated temperatures result in increased core body temperatures, blood hyperosmolality, and dehydration. Assisted by a research librarian, a literature search was undertaken of major databases (PubMed, Embase, and Google Scholar), with delimiters of publication between 2019 and 2024 and human subjects, and 477 studies were retrieved. After meticulous screening, 20 relevant articles were analyzed. Evidence linking climate change impact to increased risk for pregnant people with SCD is lacking. Further research is needed to examine the phenomenon and mitigate this unique risk of climate change. SCD clinical guidelines stress the importance of preventing dehydration. Clinicians play a critical role in educating this vulnerable population about risks, including dehydration and exposure to extreme heat.

Evaluating Heat Stress in Occupational Setting with No Established Safety Standards Using Collective Data from Wearable Biosensors

In recent years, living and occupational environments have been increasingly exposed to extreme heat. While the risk of heatstroke rises with greater heat stress, conventional knowledge and safety standards may no longer adequately assess heat stress under such extreme conditions. To address this issue, we propose a method for evaluating heat stress using collective data from wearable biosensors that monitor heart rate and physical activity in a group of workers. The novelty of this approach lies in utilizing collective data from wearable biosensors to assess environmental heat stress rather than individual health status. To quantify heat stress in specific environments or conditions, we introduce the heart rate response intercept, defined as the heart rate at 1 MET when the heart rate response to physical activity is approximated linearly. Using this heat stress index, we examined the effects of ambient temperature, aging, and obesity on heat stress. Our findings indicate that heat stress among obese workers was significantly high and should not be overlooked. Furthermore, because this method can quantify the effectiveness of heatstroke countermeasures, it serves as a valuable tool for improving occupational environments.

Mapping climate change interaction with human health through DPSIR framework: Qatar perspective

This study investigates the interactions between climate change and human health with a particular focus on Qatar, using the DPSIR (Driving Forces, Pressures, States, Impacts, Responses) framework. Key drivers, including economic development and population growth, contribute to increased greenhouse gas (GHG) emissions, exerting pressure on Qatar's climate through rising temperatures and altered precipitation patterns, as modeled by the MIT Regional Climate Model (MRCM). The findings reveal critical gaps in understanding the state of climate-health interactions, including insufficient disease data, incomplete climate-health linkages, and significant research gaps. These limitations hinder targeted responses to climate-sensitive diseases, which have shown an increase over the years. The study identifies the pathways through which climatic shifts contribute to immediate health risks, such as heat-related illnesses and respiratory conditions, as well as long-term impacts, including chronic diseases and mental health challenges. Despite Qatar's efforts through national and international strategies, the DPSIR analysis highlights the urgent need for enhanced research, improved data collection, and tailored actions to address these challenges. Strengthened adaptation, resilience-building, and emission reduction strategies remain essential for safeguarding public health in the face of accelerating climate change.

Coal: in a burning world, the dark side of energy still rules

The world registered record temperatures in the last years, with 2024 being the hottest year ever recorded and the first one to surpass the 1.5ºC limit defined by the Paris Agreement. Coal was key to the Industrial Revolution and along with petroleum, was essential to world development. However, coal is the most pollutant of fossil fuels, generating more CO2 and particulate material. Coal-derived air pollution is associated with several diseases including respiratory diseases such as chronic obstructive pulmonary disease and lower respiratory infections, cerebrovascular disease, ischaemic heart disease and lung cancer. Air pollution caused by coal and other fossil fuels causes millions of deaths a year. Despite its negative impacts on human health and climate change, coal has been extensively used for electricity generation in the last four decades and is still responsible for more than 35% of all the electricity produced in the world, with countries like Australia, Indonesia, Poland, India and China showing a much higher coal dependency from 45% to 75% in 2023. However, countries like UK, Denmark, Portugal and Spain heavily reduced coal use showing that a transition away from coal is possible and could be used by other nations.

[Effects of high thermal stress on health-a nationwide analysis based on statutory health insurance routine data between 2012 and 2021]

BACKGROUND

The extent to which statutory health insurance (SHI) data can be used to map associations between thermal stress and heat-related diseases is still unclear. The aim of this study is to analyse the association between climate variability and heat-associated diseases using insurance data.

METHODS

The study is based on claims data (outpatient and stationary) from health insurance companies in Germany for the years 2012-2021, covering approximately 11 million people with statutory health insurance. Four heat-related ICD-10 diagnoses were considered: T67 (heat and sun damage), E86 (volume depletion), N17 (acute renal failure) and N19 (renal insufficiency). Thermal conditions were quantified using meteorological variables. The evaluation was carried out on a federal state-specific basis for the second and third quarters (Q2, Q3) using descriptive methods and correlation analyses with repeated measurements.

RESULTS

The years 2016, 2018 and 2020 were characterised by high temperatures. Compared with Q2, Q3 was associated with higher thermal stress and more heat-related diagnoses on average during the entire observational period. Nationally, diagnoses of heat and sun damage (outpatient) correlated with the number of hot days (rmw = 0.86 [0.81; 0.90]). Although heat stress is lower in the second quarter, a similar correlation is found here (rmw = 0.76 [0.68; 0.82]). This striking association was also maintained when analysing the federal states specifically.

DISCUSSION

The article shows that associations between thermal stress and morbidity can also be found in routine SHI data. Against the background of an increase in high thermal stress due to climate change, this article highlights the need for adaptation measures.

Heat-Related Illness in California Firefighters, 2001-2020

BACKGROUND

Firefighters have a higher rate of heat-related illness (HRI) compared to other occupations. Given the changing climate, firefighters' risk of occupational HRI merits attention. Therefore, we aimed to identify demographic, temporal, and geographic risk factors associated with occupational HRI in California firefighters between 2001 and 2020.

METHODS

Within the California Workers' Compensation Information Systems (WCIS), we identified firefighters from 2001 to 2020 using industry and class codes and assigned occupation titles using the NIOSH Industry and Occupation Computerized Coding system (NIOCCS). HRI claims among firefighters were identified using International Classification of Diseases (ICD) Ninth or Tenth revision codes, WCIS nature and cause of injury codes, and keywords. We calculated HRI incidence rates adjusted by sex, age, year, and county. Estimates of California firefighter employment were obtained from the American Community Survey.

RESULTS

We identified 2185 firefighter HRI claims between 2001 and 2020 (305.5 claims/100,000 firefighters, 90% CI: 278.7-740.7). Firefighters aged 18 to 29 years had a statistically significant higher risk of HRI compared to those aged 40 to 49 years (rate ratio = 3.5, 90% CI: 3.1-3.9). The HRI rate increased over time, and the risk from 2016 to 2020 was 1.8 times higher than it was from 2001 to 2005 (90% CI: 1.7-1.9). Northern California counties, including Shasta (2313.9) and Sacramento (1772.1), had the highest HRI rates.

CONCLUSIONS

Firefighters in certain demographic groups and northern California counties were at highest risk of HRI. With rising temperatures and larger wildfires, additional prevention efforts are needed to reduce HRI in California firefighters.

Moderately elevated ambient temperature is associated with mortality in dialysis patients, but not in transplant patients

Background

In many parts of the world, heat waves have been associated with excess morbidity and mortality in the general population. Studies on the effects of high-temperature exposure in kidney transplantation are lacking and are scare in dialysis patients. The aim of this study was to investigate the association between high temperatures and mortality for chronic kidney disease (CKD) stage 5 patients treated with dialysis or with a kidney graft in France using various definition of elevated temperature.

Methods

In this retrospective cohort study, the association between temperature indicators and mortality was analysed with Poisson models taking into account the trend over time and seasonality and possible confounding factors. Models were compared by their AIC. All patients treated with RRT between 2012 and 2022 in France were extracted from the national REIN registry. Various definitions of elevated temperatures were explored based on all temperature measured at one station per district per hour and per day, from June to September during the years 2012-2022 in Metropolitan France.

Results

Between June and September, over the years 2012-2022, temperatures varied from 6.7 to 45.4°C. During this period, 20 174 deaths were recorded among 116 808 dialysis patients and 3340 among 64 531 transplanted patients. A maximum temperature >32.5°C was associated with mortality and an incidence ratio (IR) of 1.09 (1.04-1.15) in the dialysed population. No association was found among transplanted patients.

Conclusions

Further analyses are needed to confirm these results and better understand the biological and clinical impact of heat intensity and the cumulative effect with other environmental factors such as air pollution. More detailed studies on reasons for hospitalizations and causes of death are also planned.

Heatstroke characteristics and meteorological conditions in Hefei, China: thresholds and driving factors

BACKGROUND

Due to climate change and rapid urbanization, the frequency of heatwave events in East China has increased considerably since the 21st century, which has a considerable influence on human health, such as heatstroke. However, few studies have been conducted in this region on the relationship between heatstroke and meteorological conditions. To address this point, this study aimed to analyze the characteristics of heatstroke and their relationship with meteorological conditions in Hefei, China.

METHODS

The 2008-2022 heatstroke data from Hefei Center for Disease Control and Prevention was used. The relationship between heatstroke and meteorological conditions was discussed by statistical methods, such as correlation analysis, cluster analysis and linear regression analysis.

RESULTS

The number of heatstroke cases fluctuated upward from 36 cases in 2008 to 1051 cases in 2022, with 71.5% of all cases for males and females accounting for 28.5%. The highest frequency of heatstroke occurrence was found to be concentrated in the middle age group (40-59 years old). According to the statistical analysis, air temperature and relative humidity were the most important meteorological factors that influenced the occurrence of heatstroke. Then a threshold system of meteorological factors for heatstroke was established by utilizing the relationship: daily average temperature (T) ≥ 30 °C & daily average relative humidity (RH) ≤ 80% and daily maximum temperature (Tmax) ≥ 35 °C & daily minimum relative humidity (RHmin) ≤ 65%. The threshold in group outbreak areas was stricter than it in high incidence areas. Furthermore, the Pacific Subtropical High (PSH) was found to be the primary climatic factor that determined the occurrence of heatstroke occurrence on a seasonal scale. In addition, significant differences in heatstroke risk were found among different groups of people. Heatstroke risk was substantially higher in males than in females due to larger opportunities for outdoor labor. The reduced physical fitness of elderly people raised the risk of heatstroke more than other age groups in extremely high temperatures.

CONCLUSIONS

A meteorological threshold system had been established to forecast heatstroke occurrence in a short-term time, and a key climate driving factor of heatstroke was found for long-term heatstroke prediction in Hefei. These findings could facilitate the disease control department to take preventive and control measures to reduce the impact of heatstroke on human health and society.

Associations between anthropogenic heat emissions and serum lipids among adults in northeastern China

Few epidemiological studies have investigated associations between anthropogenic heat emissions (AE) and serum lipids. We recruited 15,477 adults from 33 communities in northeastern China in 2009. We estimated AE flux by using data on energy consumption and socio-economic statistics covering building, transportation, industry, and human metabolism. We assessed the associations between AE and blood lipids and dyslipidemia prevalence using the restricted cubic spline models. The regression coefficients (β) and the 95% CI of total cholesterol for the 75th and 95th percentiles of the exposure were 0.23 mmol/L (95% CI: 0.15, 0.30) and 0.25 mmol/L (95% CI: 0.18, 0.32). We also found AE was positively associated with dyslipidemia. Participants who were female or who had low incomes exhibited more pronounced associations. Our research showed that exposure to AE was significantly associated with serum lipids. These novel, valuable findings are useful to inform policymakers to estimate the risks to human health from anthropogenic heat.

Uneven heat burden in the sunshine state: Spatial patterns and socio-economic disparities of heat-related illness in Florida

Climate change has increased the frequency and severity of extreme heat events globally, adversely affecting socio-economic conditions and public health. However, extreme heat has disparate effects on different population groups and the socio-economic determinants of its health effects are not well understood. In this study, we analyzed the spatial patterns of heat-related illness (HRI) visit rates at the zip-code level in Florida and applied statistical methods to examine the relationships between HRIs and environmental and socio-economic variables. Hierarchical regression analysis was used to evaluate the socio-economic effects on HRI visit rates under the same heat conditions. This is a two-step approach: we first included heat indicators in the baseline model and then added the socio-economic variables to assess their unique contributions in predicting HRI visits. Our findings indicate that temperature can only explain a small fraction of the variance in HRI cases (R2 = 0.04, p < 0.01), while socio-economic variables show stronger associations (R2 = 0.42, p < 0.01 in urban areas and R2 = 0.20, p < 0.01 in rural areas). Notably, marginalized and disadvantaged populations (e.g., individuals in poverty, those employed in construction, and those with disabilities) are positively associated with HRIs (p < 0.01). These findings highlight the disproportionate impacts of heat-related health issues on disadvantaged groups, calling for climate justice policy interventions. Additionally, a comparative analysis between rural and urban areas revealed different determinants of HRIs. Our study enhances the understanding of the socio-economic determinants and disparities of HRIs in Florida, providing actionable insights for policymakers and health agencies to prioritize emergency services and heat resilience planning.

Effectiveness of a Multifaceted Intervention (TEMP) for Prevention of Occupational Heat-Related Illness among Outdoor Workers in the Power Grid Industry: A Cluster Randomized Controlled Trial

BACKGROUND

Occupational heat-related illness (OHI) is a health threat to workers that can be fatal in severe cases. Effective and feasible measures are urgently needed to prevent OHI.

OBJECTIVES

We evaluated the effectiveness of a multifaceted intervention, TEMP, in reducing the OHI risk among outdoor workers in the power grid industry.

METHODS

A cluster randomized controlled trial was conducted with power grid outdoor workers in Southern China from 4 July 2022 to 28 August 2022. Work groups were randomly allocated (1:1) to the intervention or control groups. The multifaceted intervention TEMP comprised mobile application (app)-based education training (T), personal protective equipment [PPE (E)], OHI risk monitoring (M), and educational posters (P). Four follow-ups were conducted every 2 wk after the trial began. The primary outcome was the OHI incidence, and the secondary outcome was PPE usage. The app usage was considered as the compliance of intervention in the intervention group. The primary analysis used was intention-to-treat analysis. Multilevel analyses using random effects logistic regression models were performed to compare the odds of OHI between the two groups, adjusted for individual-level (education and work position) and work-related (including water intake when feeling thirsty, cooling measures, and poor sleep before work) covariates.

RESULTS

Of 528 participants, 422 (79.92%) were males, and the mean ± SD age was 36.36 ± 8.18 y. The primary outcome, OHI incidence, was 1.80% in the intervention group and 4.82% in the control group at the end of the whole follow-up. OHI mainly occurred between 1100 and 1500 hours, with nausea, significantly increased heart rate, and oliguria being the top three reported OHI symptoms. Compared with the control group, the adjusted odds ratios between the intervention group and control group were 0.73 [95% confidence interval (CI): 0.30, 1.76] in the first follow-up wave, with 0.38 (95% CI: 0.15, 0.97), 0.29 (95% CI: 0.08, 1.05), and 0.39 (95% CI: 0.13, 1.19) in the following three follow-up waves, respectively. The intervention also significantly improved PPE usage in the intervention group.

DISCUSSIONS

This multifaceted intervention reduced the OHI risk among outdoor workers in the power grid industry. However, further research is needed to design a more flexible intervention strategy and evaluate its effectiveness in a larger population. https://doi.org/10.1289/EHP14172.

Stimulant medications effects in heat-related illness in ADHD patients: a large database study

Introduction

Attention Deficit Hyperactivity Disorder (ADHD), a prevalent neurodevelopmental disorder affecting a significant portion of the population, is commonly managed with stimulant medications. These medications, while effective, have been associated with thermoregulatory dysfunction and an increased risk of heat-related adverse events. The current study sought to compare the incidence of such events in ADHD patients receiving stimulant medications with those not on these treatments.

Methods

A retrospective cohort study was conducted utilizing de-identified electronic medical records from a Global Research Network. The study population comprised ADHD patients on stimulant medication aged 6-24 years, with a comparison group of ADHD patients not receiving stimulant medications. Patients were followed from the date of first cohort inclusion (index event) for one year to track heat-related illnesses, including dehydration, hyperthermia, heat stroke, and other heat-related conditions. Propensity score matching was employed to balance baseline characteristics (age, gender) between cohorts. Risk ratios, odds ratios, and hazard ratios were calculated to assess the incidence of heat-related illnesses between groups. Statistical analysis was performed on the TriNetX platform, with survival analysis conducted via Kaplan-Meier estimates.

Results

Analysis revealed a decreased risk of heat-related illnesses in the stimulant medication group, with a risk ratio of 0.559(95% CI: 0.485, 0.644). The mean number of events was also lower in the stimulants medication group (p=0.028). Additionally, Kaplan-Meier survival analysis indicated a higher probability of remaining free from heat-related illnesses in the stimulant group over a one-year period, with a statistically significant difference (log-rank test, χ² = 93.035, p < 0.0001).

Discussion

These results suggest that stimulant medications may be associated with a reduced risk of heat-related illnesses in ADHD patients, potentially contributing to better overall outcomes in this population. Further research is warranted to explore the underlying mechanisms and to confirm these findings across larger and more varied patient populations.

Identifying climatic drivers of forage quantity and quality in Mediterranean rangelands using remote sensing

Rangelands are dynamic ecosystems shaped by fluctuations in precipitation, temperature, and grazing intensity. Accurate assessment of forage availability is critical for optimizing land use, preventing overgrazing, and mitigating degradation, especially under future climate change scenarios. This study employed a multi-scale approach to monitor pasture using Sentinel-2 satellite imagery, calibrated with ground truth measurements, and enhanced with drone-derived vegetation cover estimates. The research was conducted in a Mediterranean grassland ecosystem under varying grazing intensities in northeastern Israel. A time series of Sentinel-2 images from 2018 to 2023 was analyzed to monitor five vegetation growth cycles. We evaluated how climate variables, such as temperature, rainfall, and vapor pressure deficit (VPD), impacted forage availability and nutritional quality. Over the past three decades, significant climatological trends showed increasing temperatures and more concentrated winter rainfall. Correlation analysis between field data and Sentinel-2 imagery demonstrated strong agreement (R2 = 0.73 for biomass and 0.72 for forage quality), validating the effectiveness of this integrated remote sensing approach. Moderate grazing reduced forage quantity but improved its quality, while extreme weather events, including drought and heatwaves, negatively impacted forage biomass and quality. Key meteorological indices, including the Standardized Precipitation-Evapotranspiration Index (SPEI) and the Simple Daily Intensity Index (SDII), were found to influence forage quantity, indicating that drought stress and concentrated rainfall events reduced biomass production. Higher values of daily temperature range and vapor pressure deficit adversely impacted forage quality. This study highlights the importance of adaptive management strategies to mitigate the projected reductions in forage quantity and quality due to climate change. The methodologies developed offer novel insights into improving ecological monitoring for sustainable rangeland management under changing climatic conditions.

Exceptional heatwaves and mortality in Europe: Greater impacts since the coronavirus disease 2019 outbreak

Record-breaking hot weather (exceptional heatwaves) has been increasingly common worldwide, posing a significant threat to human health. However, little is known about the effect of these exceptional heatwaves on mortality in Europe, especially since the coronavirus disease 2019 (COVID-19) outbreak, which converges with climate change to affect healthcare systems and human lives. We collected mortality data of 967 regions in 30 European countries over the last decade (2014-2023) from the Eurostat. A standard time-series analysis was used to estimate the effect of exceptional heatwaves by quasi-Poisson regression model, including the main effect (effect from heatwave intensity) and the added effect (effect from heatwave duration), on mortality for each region during two periods (before and since the COVID-19 outbreak). We used random effects meta-analysis to pool the mortality risk (i.e., relative risk [RR]) and burden (i.e., attributable fraction [AF]) associated with exceptional heatwaves, at the country level and for Europe as a whole. In Europe, the mortality burden attributable to main and added effects increased from 0.492% (95% CI: 0.488%-0.496%) to 1.276% (95% CI: 1.266%-1.285%) and from 0.307% (95% CI: 0.294%-0.318%) to 0.428% (95% CI: 0.407%-0.448%), respectively. Furthermore, substantial variations across countries were observed, with some countries such as France and Spain experiencing a large increase in the mortality burden attributable to exceptional heatwaves since the COVID-19 outbreak. Our findings underscore the urgent need for heat-health actions to consider the multi-effects of exceptional heatwaves amidst a warming climate.

The role of psychotropics on the associations between extreme temperature and heat-related outcomes among people with mental health conditions: population-based study

BACKGROUND

The association between heatwave and heat-related outcomes in people with mental health conditions with and without psychotropics was unclear.

METHODS

We identified people with severe mental illness (SMI) and depression, respectively, using Japanese claim data of Ibaraki prefecture during 1/1/2014-31/12/2021. We conducted self-controlled case series to estimate the incidence rate ratio (IRR) of heat-related illness, myocardial infarction and delirium, respectively, during 5-day pre-heatwave, heatwave, and 5-day post-heatwave periods v. all other periods (baseline) within an individual, stratified by periods prescribed psychotropics and periods not prescribed psychotropics, respectively.

RESULTS

Among people with SMI, heatwave was associated with an increased rate of heat-related illness v. baseline, with no evidence of a difference in the IRRs between those prescribed v. not prescribed antipsychotics (IRR: 1.48 [95% CI 1.40-1.56]; 1.45 [95% CI 1.35-1.56] respectively, p interaction: 0.53). Among people with depression, heatwave was similarly associated with heat-related illness, with no evidence of a difference in the IRRs between those prescribed v. not prescribed antidepressants (IRR: 1.54 [95% CI 1.46-1.64]; 1.64 [95% CI 1.57-1.71] respectively, p interaction: 0.33). Smaller increased rates of heat-related illness were also observed in pre- and post-heatwave periods, v. baseline in both cohorts. There was weak evidence of an increased risk of MI and delirium associated with heatwave v. baseline.

CONCLUSIONS

We showed an increased risk of heat-related illness, myocardial infarction and delirium associated with heatwave in people with mental health conditions regardless of whether being prescribed psychotropics. Risks of heat-related illness, myocardial infarction and delirium associated with heatwave might not be factors to influence decisions about the routine use of psychotropics.

Bridging the gender, climate, and health gap: the road to COP29

Focusing specifically on the gender-climate-health nexus, this Personal View builds on existing feminist works and analyses to discuss why intersectional approaches to climate policy and inclusive representation in climate decision making are crucial for achieving just and equitable solutions to address the impacts of climate change on human health and societies. This Personal View highlights how women, girls, and gender-diverse people often face disproportionate climate-related health impacts, particularly those who experience compounding and overlapping vulnerabilities due to current and former systems of oppression. We summarise the insufficient meaningful inclusion of gender, health, and their intersection in international climate governance. Despite the tendency to conflate gender equality with number-based representation, climate governance under the UNFCCC (1995-2023) remains dominated by men, with several countries projected to take over a decade to achieve gender parity in their Party delegations. Advancing gender-responsiveness in climate policy and implementation and promoting equitable participation in climate governance will not only improve the inclusivity and effectiveness of national strategies, but will also build more resilient, equitable, and healthier societies.

Summer Heat, Historic Redlining, and Neighborhood Walking among Older Adults: 2017 National Household Travel Survey

No known studies have examined the relationships between urban heat islands, historic redlining, and neighborhood walking in older adults. We assessed whether (1) individual and neighborhood characteristics (including redlining score) differ by neighborhood summer land surface temperature (LST); (2) higher LST is associated with less neighborhood walking, and whether associations differ by historic redlining score; and (3) neighborhoods with discriminatory redlining scores have greater LSTs. We used data on 3982 ≥ 65 years old from the 2017 National Household Travel Survey. Multivariable negative binomial and linear regressions tested associations between LST z-score (comparing participant's neighborhood LST to surrounding region's LST) and self-reported neighborhood walking and the association between living in neighborhoods redlined as "definitely declining" or "hazardous" (versus "still desirable"/"best") and LST z-score. LSTs were higher for those in neighborhoods with higher area deprivation scores and more African American/Black residents. Older adults living in neighborhoods with higher summer LST z-scores had fewer minutes of neighborhood walking/day. This association seemed limited to individuals with neighborhood redlining scores of "still desirable"/"best." Neighborhood redlining scores of "definitely declining" or "hazardous" (versus "still desirable" and "best") were associated with greater neighborhood summer LSTs. Overall, these findings suggest that historically redlined neighborhoods may experience urban heat island effects more often. While older adults living in hotter neighborhoods with "still desirable" or "best" redlining scores may less often engage in neighborhood walking, those in neighborhoods with redlining scores of "definitely declining" and "hazardous" do not seem to decrease neighborhood walking with higher LSTs. Future work is needed to elucidate the impact of extreme heat on health-promoting behaviors such as walking and the types of interventions that can successfully counteract negative impacts on historically disadvantaged communities.

Disease Burden in the Context of Disasters: Insights from Over 6.7 million Respondents in the Bangladesh Disaster-Related Statistics of 2021

OBJECTIVES

The objective of this study was to explore the burden of disasters and adverse health outcomes during and following disasters in Bangladesh.

METHODS

We analyzed 6 788 947 respondents' data from a cross-sectional and nationally representative 2021 Bangladesh Disaster-related Statistics (BDRS). The key explanatory variables were the types of disasters respondents faced, while the outcome variables were the disease burden during and following disasters. Descriptive statistics were used to determine disease burden. A multilevel mixed-effects logistic regression model assessed the association between disease burden and disaster types, along with socio-demographic characteristics of respondents.

RESULTS

Nearly 50% of respondents experienced diseases during disasters, rising to 53.4% afterward. Fever, cough and diarrhea were prevalent during and after disasters, with increases in skin diseases, malnutrition, and asthma post-disaster. Vulnerable groups, such as children aged 0-4, hijra individuals, those with lower education, people with disabilities, and rural residents, especially in Chattogram, Rangpur, and Sylhet divisions, were most affected. Floods, cyclones, thunderstorms, and hailstorms significantly increased disease likelihood during and after disasters.

CONCLUSIONS

The study underscores the complex relationship between disasters and health outcomes in Bangladesh, stressing the need for targeted public health interventions, improved health care infrastructure, and evidence-based policies to mitigate disaster-related health risks.

Associations of heat with diseases and specific symptoms in Flanders, Belgium: An 8-year retrospective study of general practitioner registration data

INTRODUCTION

Global temperature rise has become a major health concern. Most previous studies on the impact of heat on morbidity have used hospital data.

OBJECTIVE

This study aimed to quantify the association between ambient temperature and a variety of potentially heat-related medical conditions and symptoms using general practitioner (GP) data, in Flanders, Belgium.

METHODS

We used eight years (2012-2019) of aggregated data of daily GP visits during the Belgian summer period (May-September). A distributed lag nonlinear model (DLNM) with time-stratified conditional quasi-Poisson regression was used to account for the non-linear and delayed effect of temperature indicators (minimum, mean and maximum). We controlled for potential confounders such as particulate matter, humidity, and ozone.

RESULTS

The overall (lag0-14) association between heat and most of the outcomes was J-shaped, with an increased risk of disease observed at higher temperatures. The associations were more pronounced using the minimum temperatures indicator. Comparing the 99th (20 °C) to the minimum morbidity temperature (MMT) of the minimum temperature distribution during summer, the relative risk (RR) was significantly higher for heat-related general symptoms (RR = 1.30 [95 % CI: 1.07, 1.57]), otitis externa (RR = 4.87 [95 % CI:2.98, 7.98]), general heart problems (RR = 2.43 [95 % CI: 1.33, 4.42]), venous problems (RR = 2.48 [95 % CI:1.55, 3.96]), respiratory complaints (RR = 1.97 [95 % CI: 1.25, 3.09]), skin problems (RR = 3.26 [95 % CI: 2.51, 4.25]), and urinary infections (RR = 1.37 [95 % CI: 1.11, 1.69]). However, we did not find evidence for heat-related increases in gastrointestinal problems, cerebrovascular events, cardiovascular events, arrhythmia, mental health problems, upper respiratory problems and lower respiratory problems. An increased risk of allergy was observed when the minimum temperature reached 17.8 °C (RR = 1.50 [95 % CI: 1.23, 1.83]). Acute effects of heat were observed (largest effects at the first few lags).

SUMMARY

Our findings indicated that the occurrence of certain symptoms and illnesses during summer season is associated to high temperature or environmental exposures that are augmented by elevated temperatures. Overall, unlike hospitalization data, GP visits data provide broader population coverage, revealing a more accurate representation of heat-health association.

Projections of Climate Change Impact on Acute Heat Illnesses in Taiwan: Case-Crossover Study

Background

With global warming, the number of days with extreme heat is expected to increase and may cause more acute heat illnesses. While decreasing emissions may mitigate the climate impacts, its effectiveness in reducing acute heat illnesses remains uncertain. Taiwan has established a real-time epidemic surveillance and early warning system to monitor acute heat illnesses since January 1, 2011. Predicting the number of acute heat illnesses requires forecasting temperature changes that are influenced by adaptation policies.

Objective

The aim of this study was to estimate the changes in the number of acute heat illnesses under different adaptation policies.

Methods

We obtained the numbers of acute heat illnesses in Taiwan from January 2011 to July 2023 using emergency department visit data from the real-time epidemic surveillance and early warning system. We used segmented linear regression to identify the join point as a nonoptimal temperature threshold. We projected the temperature distribution and excess acute heat illnesses through the end of the century when Taiwan adopts the "Sustainability (shared socioeconomic pathways 1-2.6 [SSP1-2.6])," "Middle of the road (SSP2-4.5)," "Regional rivalry (SSP3-7.0)," and "Fossil-fueled development (SSP5-8.5)" scenarios. Distributed lag nonlinear models were used to analyze the attributable number (AN) and attributable fraction (AF) of acute heat illnesses caused by nonoptimal temperature.

Results

We enrolled a total of 28,661 patients with a mean age of 44.5 (SD 15.3) years up to July 2023, of whom 21,619 (75.4%) were male patients. The nonoptimal temperature was 27 °C. The relative risk of acute heat illnesses with a 1-degree increase in mean temperature was 1.71 (95% CI 1.63-1.79). In the SSP5-8.5 worst-case scenario, the mean temperature was projected to rise by +5.8 °C (SD 0.26), with the AN and AF of acute heat illnesses above nonoptimal temperature being 19,021 (95% CI 2249-35,792) and 89.9% (95% CI 89.3%-90.5%) by 2090-2099. However, if Taiwan adopts the Sustainability SSP1-2.6 scenario, the AN and AF of acute heat illnesses due to nonoptimal temperature will be reduced to 12,468 (95% CI 3233-21,704) and 62.1% (95% CI 61.2-63.1).

Conclusions

Adopting sustainable development policies can help mitigate the risk of acute heat illnesses caused by global warming.

Heat exposure impacts on urban health: A meta-analysis

The escalating health risks posed by warm weather in urban areas have become a pressing global public health issue. This study undertakes a meta-analysis to evaluate the impact of warm weather on health in urban settings. We comprehensively searched PubMed, Embase, Scopus, and Web of Science for literature published before September 6, 2023, evaluating evidence quality using the Navigation Guide Criteria. We included original studies utilizing high temperatures or heatwaves as exposure metrics and employing observational designs. A meta-analysis was carried out to assess the relative risk (RR) of the association between high temperatures (or heatwaves) and disease outcomes. Out of 12,893 studies identified, 188 met the inclusion criteria for meta-analysis. Results demonstrate a statistically significant association between a 1 °C temperature increase and a 2.1 % elevation in disease-related mortality (RR 1.021 [95 % CI 1.018-1.023]), alongside a 1.1 % increase in morbidity (RR 1.011 [95 % CI 1.007-1.016]). Heatwaves also showed associations with increased total mortality (RR 1.224 [95 % CI 1.186-1.264]) and morbidity (RR 1.038 [95 % CI 1.010-1.066]). Subgroup analyses for diseases, sex, age, climatic zones, countries, and time periods consistently indicated heightened disease-related mortality and morbidity linked to high temperatures. Notably, China's urban population faced an elevated mortality risk (RR 1.027 [95 % CI 1.018-1.036]) compared to other countries (RR 1.021 [95 % CI 1.019-1.024]). Mortality associated with high temperatures after 2007 (RR 1.022 [95 % CI 1.015-1.029]) was higher than before 2007 (RR 1.017 [95 % CI 1.013-1.021]), reflecting increased health risks as the global warming accelerates. Our findings underscore the positive association between rising temperatures and/or heatwaves and adverse health outcomes in urban populations. The widespread exposure to high temperatures amplifies health risks across various diseases, demographics, climates, and countries, with potential exacerbation under ongoing global warming. Further research is imperative to delineate factors influencing altered heat exposure impacts.

The impact of air temperature and humidity on Children's blood pressure mediated by Lipids: A prospective cohort study

OBJECTIVES

Few studies illustrate the mechanism between air temperature and blood pressure (BP) in childhood. This study aims to investigate the associations between air temperature, humidity exposure, and BP trajectories in children and adolescents, and explore the potential mediating roles of lipid profiles in these relationships.

METHODS

This prospective cohort study included 5,971 children with 10,800 person-times measurements at baseline from the Chongqing Health Cohort, with evaluations conducted in 2014-2015 (baseline) and follow-ups in 2016 (urban areas) and 2019 (urban and rural areas). Multilevel mixed-effects models were used to analyse the impacts of air temperature and humidity on BP levels and the incidence of elevated BP, while accounting for potential confounders. Mediation analyses were performed to evaluate the mediating effects of lipid profiles, including low-density lipoprotein (LDL), total cholesterol (TC), and specific lipid species.

RESULTS

After adjusting for covariates, higher air temperature quartiles were associated with both decreased BP levels and elevated BP risk (RR: 0.83; 95 % CIs: 0.78, 0.89; P = 0.028). Conversely, higher humidity quartiles exhibited a U-shaped relationship with BP levels. Greater variability in air temperature was linked to increase BP levels. The cumulative effects of air temperature exposure on BP were significant from pregnancy to age 10, with females exhibiting larger effects (β:-3.291, 95 % CIs: -4.242,-2.340, P < 0.001). LDL and TC partially mediated the associations between air temperature and BP levels, particularly in males. Specific lipid species, including SM (d21:1), LPC (17:0), and PC (O-36:3), also exhibited significant mediating effects.

CONCLUSIONS

This study provides novel insights into the intricate interplay between air temperature, humidity, lipid metabolism, and blood pressure regulation in children. Lower average temperatures and extreme humidity levels were associated with increased risks of elevated BP, potentially mediated by lipid profiles. Early interventions targeting air temperature exposure and lipid metabolism could mitigate hypertension risk, promoting improved cardiovascular outcomes in children.

Physiological responses to heat exposure in a general population cohort in Denmark: the Lolland-Falster Health Study

BACKGROUND

Rising global temperatures due to climate change pose a health risk. Mortality and morbidity increase during heat events affects various organ systems. While warmer countries face higher risks, even colder regions show elevated mortality during hot periods. This study examines physiological responses to heat exposure using data from the general Danish population cohort Lolland-Falster Health Study (LOFUS) during the summers of 2016-2019.

METHODS

In this cross-sectional study, we analysed health data from 3804 individuals aged ≥15 years. Data were analysed across organ systems: cardiovascular system, lung function, renal system, inflammation, coagulation, and liver function. Meteorological data from the Danish Meteorological Institute provided information on temperature and humidity. Heat exposure was defined as one day ≥28°C heat index the day prior to examination. Adjusted multiple linear regression was applied to analyse differences between the two groups.

RESULTS

There were 46 of 368 days with temperatures ≥28°C heat index. In total, 396 participants were heat-exposed (exposure group), while 3408 constituted the unexposed group. Heat exposure was associated with lower systolic blood pressure (-3.82 mm Hg [-5.72; -1.93]), higher heart rate (1.71 beats/min [0.45; 2.98]), lower oxygen saturation (-0.28% [-0.45; -0.10]), higher sodium (0.56 mmol/l [0.33; 0.79]), and higher urine albumin (0.14 mg/l [0.02; 0.27]). No significant differences were observed in inflammation, coagulation, or liver function.

CONCLUSION

This study reveals early physiological responses to heat with one day of heat exposure ≥28°C, particularly in the cardiovascular, pulmonary, and renal systems. These findings underline the need for tailored strategies to mitigate health risks associated with rising temperatures.

Climate Change and Aging: Implications for Psychiatric Care

PURPOSE OF REVIEW

We reviewed recent evidence regarding the impact of climate change (specifically, high ambient temperatures, heatwaves, weather-related disasters, and air pollution) on older adults' mental health. We also summarized evidence regarding other medical problems that can occur in aging adults in connection with climate change, resulting in psychiatric manifestations or influencing psychopharmacological management.

RECENT FINDINGS

Older adults can experience anxiety, depressive, and/or posttraumatic stress symptoms, as well as sleep disturbances in the aftermath of climate disasters. Cognitive deficits may occur with exposure to air pollutants, heatwaves, or post-disaster. Individuals with major neurocognitive disorders and/or preexisting psychiatric illness have a higher risk of psychiatric hospitalizations after exposure to high temperatures and air pollution. There is a growing body of research regarding psychiatric clinical presentations associated with climate change in older adults. However, there is a paucity of evidence on management strategies. Future research should investigate culturally appropriate, cost-effective psychosocial and pharmacological interventions.

Burden of non-communicable diseases attributable to high temperature in a changing climate from 1990 to 2019: a global analysis

BACKGROUND

With global climate change, the health threats of ambient high temperature have received widespread attention. However, latest spatio-temporal patterns of the non-communicable diseases (NCDs) burden attributable to high temperature have not been systematically reported. We aimed to analyze vulnerable areas and populations based on a detailed profile for the NCDs burden attributable to high temperature globally.

METHODS

We obtained data from the Global Burden of Diseases (GBD) Study (2019) to describe the temporal and spatial patterns of NCDs burden attributable to high temperature globally from 1990-2019. Then we analyzed the differences by region, sex, and socio-demographic index (SDI). Finally, the age‑period‑cohort (APC) model was utilized to explore the age, period, and cohort effects of NCDs mortality caused by high temperature.

RESULTS

In 2019, the number of deaths and Disability-adjusted life years (DALYs) from high-temperature-related NCDs was about 150,000 and 3.4 million globally, of which about 70% were in South Asia and North Africa and Middle East, and the burden was higher in men. Among 204 countries and territories, the highest age-standardized mortality rate (ASMR) and age-standardized DALY rate (ASDR) were observed in Oman and United Arab Emirates, respectively. The global burden showed an upward trend from 1990 to 2019, with an EAPC of 3.66 (95%CI: 3.14-4.18) for ASMR and 3.68 (95%CI: 3.16-4.21) for ASDR. Cardiovascular diseases were the main contributors to the global burden of high-temperature-related NCDs in 2019. The age and period effect in APC model showed an increasing trend globally. There was a significant negative correlation between SDI and both ASMR (r = -0.17) and ASDR (r = -0.20) from 1990 to 2019.

CONCLUSION

There was an increasing trend of the global burden of high-temperature-related NCDs. The burden was likely to be higher in males and the elderly, as well as in countries and regions with less economically and socially developed and in tropical climates. Surveillance and prevention measures should be implemented with a focus on these vulnerable areas and susceptible populations.

Heat stroke: Pathogenesis, diagnosis, and current treatment

Recently, the incidence of heat-related illnesses has exhibited a steadily upward trend, which is closely associated with several environmental factors such as climate change and air pollution. The progression of heat-related illnesses is a continuous process and can progress to the terminal period when it transforms into heat stroke, the most severe form. Heat stroke is markedly by a core body temperature above 40°C and central nervous system dysfunction. Current knowledge suggests that the pathogenesis of heat stroke is complex and varied, including inflammatory response, oxidative stress, cell death, and coagulation dysfunction. This review consolidated recent research progress on the pathophysiology and pathogenesis of heat stroke, with a focus on the related molecular mechanisms. In addition, we reviewed common strategies and sorted out the drugs in various preclinical stages for heat stroke, aiming to offer a comprehensive research roadmap for more in-depth researches into the mechanisms of heat stroke and the reduction in the mortality of heat stroke in the future.

Projections of mortality attributable to hot ambient temperatures in Cyprus under moderate and extreme climate change scenarios

BACKGROUND

Heat-related mortality has become a growing public health concern in light of climate change. However, few studies have quantified the climate-attributable health burden in Cyprus, a recognized climate change hotspot. This study aims to estimate the heat-related mortality in Cyprus for all future decades in the 21st century under moderate (SSP2-4.5) and extreme (SSP5-8.5) climate scenarios.

METHODS

We applied distributed lag non-linear models to estimate the baseline associations between temperature and mortality from 2004 to 2019 (data obtained from Department of Meteorology of the Ministry of Agriculture, Rural Development and Environment and the Health Monitoring Unit of the Cyprus Ministry of Health). The relationships were then extrapolated to future daily mean temperatures derived from downscaled global climate projections from General Circulation Models. Attributable number of deaths were calculated to determine the excess heat-related health burden compared to the baseline decade of 2000-2009 in the additive scale. The analysis process was repeated for all-cause, cardiovascular, and respiratory mortality and mortality among males, females, and adults younger or older than 65. We assumed a static population and demographic structure, no adaptation to hot temperatures over time, and did not evaluate potential interaction between temperature and humidity.

RESULTS

Compared to 2000-2009, heat-related total mortality is projected to increase by 2.7% (95% empirical confidence interval: 0.6, 4.0) and 4.75% (2.2, 7.1) by the end of the century in the moderate and extreme climate scenarios, respectively. Cardiovascular disease is expected to be an important cause of heat-related death with projected increases of 3.4% (0.7, 5.1) and 6% (2.6, 9.0) by the end of the century. Reducing carbon emission to the moderate scenario can help avoid 75% of the predicted increase in all-cause heat-related mortality by the end of the century relative to the extreme scenario.

CONCLUSIONS

Our findings suggest that climate change mitigation and sustainable adaptation strategies are crucial to reduce the anticipated heat-attributable health burden, particularly in Cyprus, where adaptation strategies such as air conditioning is nearing capacity.

Unraveling the urban climate crisis: Exploring the nexus of urbanization, climate change, and their impacts on the environment and human well-being - A global perspective

The accelerating pace of urbanization, coupled with the intensifying impacts of climate change, poses unprecedented challenges to both the environment and human well-being. In this review, we delved into the intricate interaction between climate change and urbanization and the various effects they have on the environment and human well-being, shedding light on the emergent urban climate crisis. Urban areas serve as epicenters for diverse socio-economic activities, yet they also contribute significantly to global greenhouse gas emissions and environmental degradation. Through an interdisciplinary lens, we explored the root causes of the urban climate crisis, examining how rapid urbanization exacerbates climate change and vice versa. By synthesizing current research and case studies, we elucidate the various environmental and social ramifications of this nexus, ranging from urban heat island effects to heightened vulnerability to extreme weather events. Furthermore, we delve into the unequal distribution of climate risks within urban populations, highlighting the disproportionate burden borne by marginalized communities. Finally, the chapter presents strategies and interventions for mitigating and adapting to the urban climate crisis, emphasizing the imperative of holistic and equitable approaches that prioritize both environmental sustainability and human well-being. Overall, this review calls for concerted efforts to unravel the complexities of the urban climate crisis and forge a path toward resilient, sustainable, and equitable urban futures.

Impact of Ambient Temperature on Mortality Burden and Spatial Heterogeneity in 16 Prefecture-Level Cities of a Low-Latitude Plateau Area in Yunnan Province: Time-Series Study

Background

The relation between climate change and human health has become one of the major worldwide public health issues. However, the evidence for low-latitude plateau regions is limited, where the climate is unique and diverse with a complex geography and topography.

objectives

This study aimed to evaluate the effect of ambient temperature on the mortality burden of nonaccidental deaths in Yunnan Province and to further explore its spatial heterogeneity among different regions.

Methods

We collected mortality and meteorological data from all 129 counties in Yunnan Province from 2014 to 2020, and 16 prefecture-level cities were analyzed as units. A distributed lagged nonlinear model was used to estimate the effect of temperature exposure on years of life lost (YLL) for nonaccidental deaths in each prefecture-level city. The attributable fraction of YLL due to ambient temperature was calculated. A multivariate meta-analysis was used to obtain an overall aggregated estimate of effects, and spatial heterogeneity among 16 prefecture-level cities was evaluated by adjusting the city-specific geographical characteristics, demographic characteristics, economic factors, and health resources factors.

Results

The temperature-YLL association was nonlinear and followed slide-shaped curves in all regions. The cumulative cold and heat effect estimates along lag 0-21 days on YLL for nonaccidental deaths were 403.16 (95% empirical confidence interval [eCI] 148.14-615.18) and 247.83 (95% eCI 45.73-418.85), respectively. The attributable fraction for nonaccidental mortality due to daily mean temperature was 7.45% (95% eCI 3.73%-10.38%). Cold temperature was responsible for most of the mortality burden (4.61%, 95% eCI 1.70-7.04), whereas the burden due to heat was 2.84% (95% eCI 0.58-4.83). The vulnerable subpopulations include male individuals, people aged <75 years, people with education below junior college level, farmers, nonmarried individuals, and ethnic minorities. In the cause-specific subgroup analysis, the total attributable fraction (%) for mean temperature was 13.97% (95% eCI 6.70-14.02) for heart disease, 11.12% (95% eCI 2.52-16.82) for respiratory disease, 10.85% (95% eCI 6.70-14.02) for cardiovascular disease, and 10.13% (95% eCI 6.03-13.18) for stroke. The attributable risk of cold effect for cardiovascular disease was higher than that for respiratory disease cause of death (9.71% vs 4.54%). Furthermore, we found 48.2% heterogeneity in the effect of mean temperature on YLL after considering the inherent characteristics of the 16 prefecture-level cities, with urbanization rate accounting for the highest proportion of heterogeneity (15.7%) among urban characteristics.

Conclusions

This study suggests that the cold effect dominated the total effect of temperature on mortality burden in Yunnan Province, and its effect was heterogeneous among different regions, which provides a basis for spatial planning and health policy formulation for disease prevention.

Combination of Dasatinib and Quercetin alleviates heat stress-induced cognitive deficits in aged and young adult male mice

OBJECTIVE

Dasatinib and quercetin (D & Q) have demonstrated promise in improving aged-related pathophysiological dysfunctions in humans and mice. Herein we aimed to ascertain whether the heat stress (HS)-induced cognitive deficits in aged or even young adult male mice can be reduced by D & Q therapy.

METHODS

Before the onset of HS, animals were pre-treated with D & Q or placebo for 3 consecutive days every 2 weeks over a 10-week period. Cognitive function, intestinal barrier permeability, and blood-brain barrier permeability were assessed.

RESULTS

Compared to the non-HS young adult male mice, the HS young adult male mice or the aged male mice had significantly lesser extents of the exacerbated stress reactions, intestinal barrier disruption, endotoxemia, systemic inflammation and oxidative stress, blood-brain barrier disruption, hippocampal inflammation and oxidative stress, and cognitive deficits evaluated at 7 days post-HS. All the cognitive deficits and other syndromes that occurred in young adult HS mice or in aged HS mice were significantly attenuated by D & Q therapy (P < 0.01). Compared to the young adult HS mice, the aged HS mice had significantly (P < 0.01) higher severity of cognitive deficits and other related syndromes.

CONCLUSIONS

First, our data show that aged male mice are more vulnerable to HS-induced cognitive deficits than those of the young adult male mice. Second, we demonstrate that a combination of D and Q therapy attenuates cognitive deficits in heat stressed aged or young adult male mice via broad normalization of the brain-gut-endotoxin axis function.

Investigating the impacts of climate change on hydroclimatic extremes in the Tar-Pamlico River basin, North Carolina

Evaluating the forthcoming impacts of climate change is important for formulating efficient and flexible approaches to water resource management. General Circulation Models (GCMs) are primary tools that enable scientists to study both past and potential future climate changes, as well as their impacts on policies and actions. In this work, we quantify the future projected impacts of hydroclimatic extremes on the coastal, risk-prone Tar-Pamlico River basin in North Carolina using GCMs from the Sixth International Coupled Model Intercomparison Project (CMIP6). These models incorporate projected future societal development scenarios (Shared Socioeconomic Pathways, SSPs) as defined in the Intergovernmental Panel on Climate Change (IPCC) Sixth Assessment Report (AR6). Specifically, we have utilized historical residential expansion data, the Soil and Water Assessment Tool Plus (SWAT+), the Standardized Precipitation Index (SPI), and the Interquartile Range (IQR) method for analyzing extremes from 2024 to 2100. Our findings include: (1) a trend toward wetter conditions is identified with an increase in flood events toward 2100; (2) projected increases in the severity of flood peaks are found, quantified by a rise of 21% compared to the 2000-2020 period; (3) downstream regions are forecast to experience severe droughts up to 2044; and (4) low-lying and coastal regions are found as particularly susceptible to higher flood peaks and more frequent drought events between 2045 and 2100. This work provides valuable insights into the anticipated shifts in natural disaster patterns and supports decision-makers and authorities in promoting adaptive strategies and sustainable policies to address challenges posed by future climate changes in the Tar-Pamlico region and throughout the state of North Carolina, United States.

Indoor overheating: A review of vulnerabilities, causes, and strategies to prevent adverse human health outcomes during extreme heat events

The likelihood of exposure to overheated indoor environments is increasing as climate change is exacerbating the frequency and severity of hot weather and extreme heat events (EHE). Consequently, vulnerable populations will face serious health risks from indoor overheating. While the relationship between EHE and human health has been assessed in relation to outdoor temperature, indoor temperature patterns can vary markedly from those measured outside. This is because the built environment and building characteristics can act as an important modifier of indoor temperatures. In this narrative review, we examine the physiological and behavioral determinants that influence a person's susceptibility to indoor overheating. Further, we explore how the built environment, neighborhood-level factors, and building characteristics can impact exposure to excess heat and we overview how strategies to mitigate building overheating can help reduce heat-related mortality in heat-vulnerable occupants. Finally, we discuss the effectiveness of commonly recommended personal cooling strategies that aim to mitigate dangerous increases in physiological strain during exposure to high indoor temperatures during hot weather or an EHE. As global temperatures continue to rise, the need for a research agenda specifically directed at reducing the likelihood and impact of indoor overheating on human health is paramount. This includes conducting EHE simulation studies to support the development of consensus-based heat mitigation solutions and public health messaging that provides equitable protection to heat-vulnerable people exposed to high indoor temperatures.

Escalating climate-related health risks for Hajj pilgrims to Mecca

BACKGROUND

Global temperatures are on the rise, leading to more frequent and severe heatwaves with associated health risks. Heat-related illnesses (HRIs) are an increasing threat for travellers to hot climate destinations. This study was designed to elucidate the interplay between increasing ambient temperatures, incidence of HRIs and the effectiveness of mitigation strategies during the annual Hajj mass gathering over a 40-year period.

METHODS

An observational study was conducted utilizing historical records spanning four decades of meteorological data, and the rates of heat stroke (HS) and heat exhaustion (HE) during the Hajj pilgrimage in Mecca, Saudi Arabia. With an annual population exceeding 2 million participants from over 180 countries, the study analysed temporal variations in weather conditions over two distinct Hajj hot cycles and correlated it with the occurrence of HS and HE. The effectiveness of deployed mitigation measures in alleviating health vulnerabilities between the two cycles was also assessed.

RESULTS

Throughout the study period, average dry and wet bulb temperatures in Mecca escalated by 0.4°C (Mann-Kendall P < 0.0001) and 0.2°C (Mann-Kendall P = 0.25) per decade, respectively. Both temperatures were strongly correlated with the incidence of HS and HE (P < 0.001). Despite the intensifying heat, the mitigation strategies including individual, structural and community measures were associated with a substantial 74.6% reduction in HS cases and a 47.6% decrease in case fatality rate.

CONCLUSION

The study underscores the escalating climate-related health risks in Mecca over the study period. The mitigation measures' efficacy in such a globally representative setting emphasizes the findings' generalizability and the importance of refining public health interventions in the face of rising temperatures.

Multimorbidity and emergency hospitalisations during hot weather

BACKGROUND

People with chronic diseases are a commonly listed heat-vulnerable group in heat-health action plans. While prior research identifies multiple health conditions that may increase vulnerability to ambient heat, there is minimal evidence regarding the implications of multimorbidity (two or more chronic diseases).

METHODS

From the statewide hospital registry of Queensland, Australia, we identified people aged ≥15 years who had emergency hospitalisation(s) between March 2004 and April 2016 and previously had 0, 1, 2, or ≥3 of five chronic diseases: cardiovascular disease, diabetes, mental disorders, asthma/COPD, and chronic kidney disease. We conducted time-stratified case-crossover analyses to estimate the odds ratio of hospitalisations associated with ambient heat exposure in people with different numbers, types, and combinations of chronic diseases. Ambient heat exposure was defined as a 5 °C increase in daily mean temperature above the median.

FINDINGS

There were 2,263,427 emergency hospitalisations recorded (48.7% in males and 51.3% in females). When the mean temperature increased, hospitalisation odds increased with chronic disease number, particularly in older persons (≥65 years), males, and non-indigenous people. For instance, in older persons with 0, 1, 2, or ≥3 chronic diseases, the odds ratios associated with ambient heat exposure were 1.00 (95% confidence interval: 0.96, 1.04), 1.06 (1.02, 1.09), 1.08 (1.02, 1.14), and 1.13 (1.07, 1.19), respectively. Among the chronic diseases, chronic kidney disease, and asthma/COPD, either existing alone, together, or in combination with other diseases, were associated with the highest odds of hospitalisations under ambient heat exposure.

INTERPRETATION

While individuals with multimorbidity are considered in heat-health action plans, this study suggests the need to consider specifically examining them as a distinct and vulnerable subgroup.

FUNDING

Wellcome.

The effects of extreme heat on human health in tropical Africa

This review examines high-quality research evidence that synthesises the effects of extreme heat on human health in tropical Africa. Web of Science (WoS) was used to identify research articles on the effects extreme heat, humidity, Wet-bulb Globe Temperature (WBGT), apparent temperature, wind, Heat Index, Humidex, Universal Thermal Climate Index (UTCI), heatwave, high temperature and hot climate on human health, human comfort, heat stress, heat rashes, and heat-related morbidity and mortality. A total of 5, 735 articles were initially identified, which were reduced to 100 based on a set of inclusion and exclusion criteria. The review discovered that temperatures up to 60°C have been recorded in the region and that extreme heat has many adverse effects on human health, such as worsening mental health in low-income adults, increasing the likelihood of miscarriage, and adverse effects on well-being and safety, psychological behaviour, efficiency, and social comfort of outdoor workers who spend long hours performing manual labour. Extreme heat raises the risk of death from heat-related disease, necessitating preventative measures such as adaptation methods to mitigate the adverse effects on vulnerable populations during hot weather. This study highlights the social inequalities in heat exposure and adverse health outcomes.

Severity Analysis for Occupational Heat-related Injury Using the Multinomial Logit Model

Background

Workers are often exposed to hazardous heat due to their work environment, leading to various injuries. As a result of climate change, heat-related injuries (HRIs) are becoming more problematic. This study aims to identify critical contributing factors to the severity of occupational HRIs.

Methods

This study analyzed historical injury reports from the Occupational Safety and Health Administration (OSHA). Contributing factors to the severity of HRIs were identified using text mining and model-free machine learning methods. The Multinomial Logit Model (MNL) was applied to explore the relationship between impact factors and the severity of HRIs.

Results

The results indicated a higher risk of fatal HRIs among middle-aged, older, and male workers, particularly in the construction, service, manufacturing, and agriculture industries. In addition, a higher heat index, collapses, heart attacks, and fall accidents increased the severity of HRIs, while symptoms such as dehydration, dizziness, cramps, faintness, and vomiting reduced the likelihood of fatal HRIs.

Conclusions

The severity of HRIs was significantly influenced by factors like workers' age, gender, industry type, heat index , symptoms, and secondary injuries. The findings underscore the need for tailored preventive strategies and training across different worker groups to mitigate HRIs risks.

Disparities in the impact of heat wave definitions on emergency department visits during the first year of life among preterm and full-term infants in California

INTRODUCTION

Heat waves will be aggravated due to climate change, making this a critical public health threat. However, heat wave definitions to activate alert systems can be ambiguous, highlighting the need to assess a range of definitions to identify those that contribute to the most adverse health outcomes. Additionally, children are highly susceptible to the impacts of heat waves, especially infants, despite the lack of focus on this subpopulation. We aimed to assess the relationship between 30 heat wave definitions and the first all-cause emergency department (ED) visits for California infants. We also examined modification of this relationship by preterm birth status and demographic characteristics to identify possible health disparities.

METHODS

Live-born, singleton deliveries from the Study of Outcomes in Mothers and Infants born in 2014-2018 were included. Thirty heat wave definitions were assessed based on temperature metrics (minimum/maximum temperatures), thresholds (90th; 92.5th; 95th; 97.5th; 99th percentiles), and duration (1-; 2-; 3-days). A time-stratified case-crossover design assessed heat wave impacts on ED visits using infants with a warm season ED visit (May-October) within the first year of life (n = 228,250). Effect modification by preterm birth status, age, sex, race/ethnicity, education, and delivery payment type was also investigated.

RESULTS

Infants demonstrated increased risk of an ED visit with exposure to all heat definitions. The 3-day minimum temperature 99th percentile definition had the highest adjusted odds ratio (AOR: 1.14; 95% CI: 1.05-1.23) for the total population. Term infants were more affected by some heat waves than preterm infants. Effect modification was additionally identified, such as by maternal education.

DISCUSSION

This study provides insight on the heat wave definitions that lead to adverse health outcomes and the identification of the most susceptible infants to these impacts, which has implications on heat-related interventions.

Application of the socioecological model to mitigate risks of heat illness

BACKGROUND

The socio-ecological model (SEM) is a widely used framework that can be applied to heat-related illness (HRI) in the context of multiple influencing factors that exist in society. Leaders and policymakers must intervene to mitigate the deleterious effects of climate change on those at risk.

PURPOSE

The purpose is to introduce the SEM as a framework to address the complex factors contributing to the impact of excess heat.

METHODS

Conceived through the SEM, the compounding and cumulative impact of excess heat resulting in HRI is operationalized.

DISCUSSION

The SEM provides a structure for understanding the complex nature of climate change and HRI and proposed interventions. The prevention of HRI is dependent on actions, related to practice, education, research, and advocacy across multiple levels of the SEM. The SEM has the potential to target HRI at all levels of society to reduce the harm of excess heat.

Climate change and health: rethinking public health messaging for wildfire smoke and extreme heat co-exposures

With the growing climate change crisis, public health agencies and practitioners must increasingly develop guidance documents addressing the public health risks and protective measures associated with multi-hazard events. Our Policy and Practice Review aims to assess current public health guidance and related messaging about co-exposure to wildfire smoke and extreme heat and recommend strengthened messaging to better protect people from these climate-sensitive hazards. We reviewed public health messaging published by governmental agencies between January 2013 and May 2023 in Canada and the United States. Publicly available resources were eligible if they discussed the co-occurrence of wildfire smoke and extreme heat and mentioned personal interventions (protective measures) to prevent exposure to either hazard. We reviewed local, regional, and national governmental agency messaging resources, such as online fact sheets and guidance documents. We assessed these resources according to four public health messaging themes, including (1) discussions around vulnerable groups and risk factors, (2) symptoms associated with these exposures, (3) health risks of each exposure individually, and (4) health risks from combined exposure. Additionally, we conducted a detailed assessment of current messaging about measures to mitigate exposure. We found 15 online public-facing resources that provided health messaging about co-exposure; however, only one discussed all four themes. We identified 21 distinct protective measures mentioned across the 15 resources. There is considerable variability and inconsistency regarding the types and level of detail across described protective measures. Of the identified 21 protective measures, nine may protect against both hazards simultaneously, suggesting opportunities to emphasize these particular messages to address both hazards together. More precise, complete, and coordinated public health messaging would protect against climate-sensitive health outcomes attributable to wildfire smoke and extreme heat co-exposures.

Implications of climate change on acute kidney injury

PURPOSE OF REVIEW

Climate change is an active and growing threat to human health. This review examines the evidence linking climate change to kidney diseases, with a focus on acute kidney injury (AKI).

RECENT FINDINGS

A growing body of evidence documents the adverse impact of various environmental and occupational exposures on kidney health. Extreme heat exposure increases the risk for AKI in vulnerable populations, particularly outdoor workers. These effects are being seen in both developed and developing nations, impacting equatorial as well as more northern climates. Climate change is also increasing the risk of water-borne and vector-borne infections, which are important causes of AKI in tropical regions. Due to overlapping environmental and social risk factors, populations in low-income and middle-income countries are likely to be disproportionately affected by climate-related health impacts, including heightened risk for kidney diseases.

SUMMARY

Climate change will adversely impact global kidney health over the course of the century through effects on temperature and risk of endemic infections. Alongside efforts to aggressively reduce carbon emissions, additional research is needed to guide public and environmental health policies aimed at mitigating the impact of climate change on human health.

Quantifying the contribution of industrial zones to urban heat islands: Relevance and direct impact

Industrial production activities are an important source of urban heat emissions. Quantifying the contribution of industrial zones to urban heat islands (UHIs) is crucial for urban planning and management. However, few studies have explored the quantitative relationship between land surface temperature (LST) and urban industrial zones (UIZs) at the urban scale, especially the direct impact of industrial expansion or contraction on LST. Linyi City, the largest city in Shandong Province, was selected as the study area. This study aims to analyze the spatial-temporal variation in the UIZs in Linyi City from 2013 to 2022, focusing on the quantitative relationship between LST and UIZs. Using remote sensing images, a novel spectral index (called the BCCSI) was constructed to identify factory buildings. The performance of the BCCSI was validated using five existing indices and Google Earth images. Over the past 10 years, the UIZ area of Linyi has increased by 137.16 km2. The UIZs in Linyi are mainly distributed in counties near the urban center, and counties with large UIZ areas are also hotspots for UIZ changes. Moreover, we found that the contraction or expansion of UIZs has obvious effects on LST. After the contraction (or expansion) of UIZs, the LST decreased (or increased) by 0.48 °C (0.39 °C). In addition, we found that there is an exponential relationship between LST and the industrial unit area (P value less than 0.01). This research is valuable for environmental assessment and fine management of industrial cities.

The trends of disease burden due to high temperature in Mainland China from 1990 to 2019 and its prediction to 2030

The risk of high-temperature-related diseases is increasing owing to global warming. This study aimed to assess the trend of disease burden caused by high temperatures in Mainland China from 1990 to 2019 and to predict the trend of disease burden over the next 10 years. The latest data were downloaded from the Global Burden of Disease Database (GBD) for analysis, and the disease burden related to high temperature was described by mortality and disability-adjusted life-years (DALYs) and stratified by etiology, sex, and age. Statistical analyses were performed using the R software. In 2019, there were 13,907 deaths attributed to high temperatures in Mainland China, and this was 29.55% higher than the 10,735 deaths in 1990. Overall, the age-standardized mortality and DALYs attributed to high temperatures showed a downward trend from 1990 to 2019. We observed an etiological shift in high-temperature-related diseases. The age-standardized DALYs contribution attributed to high temperatures in 1990 was mainly from communicable, maternal, neonatal, and nutritional diseases (CMNND) (21.81/100,000), followed by injury (18.30/100,000) and non-communicable diseases (10.40/100,000). In 2019, the largest contribution shifted to non-communicable diseases (10.07/100,000), followed by injuries (5.21/100,000), and CMNND (2.30/100,000). The disease burden attributed to high temperatures was higher in males than in females and increased with age. In 2030, the mortality rate and DALYs due to high temperatures are predicted to decrease further, and the largest contribution will come from chronic non-communicable diseases, the occurrence of which will remain at a high level over the next 10 years. The burden of disease due to high temperatures in Mainland China is still heavy, mainly due to population aging and an increase in non-communicable diseases.

Seasonal peak and the role of local weather in schizophrenia occurrence: A global analysis of epidemiological evidence

BACKGROUND

Many studies have shown that the onset of schizophrenia peaked in certain months within a year and the local weather conditions could affect the morbidity risk of schizophrenia. This study aimed to conduct a systematic analysis of schizophrenia seasonality in different countries of the world and to explore the effects of weather factors globally.

METHODS

We searched three databases (PubMed, Web of Science, and China National Knowledge Infrastructure) for eligible studies published up to September 2022. Schizophrenia seasonality was compared between hemispheres and within China. A meta-analysis was conducted to pool excess risk (ER, absolute percentage increase in risk) of the onset of schizophrenia associated with various weather factors including temperature (an increase or decrease of temperature as a reflection of high or low temperature; heatwave; temperature variation), precipitation, etc. RESULTS: We identified 84 relevant articles from 22 countries, mainly in China. The seasonality analysis found that the onset of schizophrenia mostly peaked in the cold season in the southern hemisphere but in the warm season in the northern hemisphere. Interestingly in China, schizophrenia seasonality presented two peaks, respectively in the late cold and warm seasons. The meta-analysis further revealed an increased risk of schizophrenia after short-term exposure to high temperature [ER%: 0.45 % (95 % confidence interval (CI): 0.14 % to 0.76 %)], low temperature [ER%: 0.52 % (95%CI: 0.29 % to 0.75 %)], heatwave [ER%: 7.26 % (95%CI: 4.45 % to 10.14 %)], temperature variation [ER%: 1.02 % (95%CI: 0.55 % to 1.50 %)], extreme precipitation [ER%: 3.96 % (95%CI: 2.29 % to 5.67 %)]. The effect of other weather factors such as sunlight on schizophrenia was scarcely investigated with inconsistent findings.

CONCLUSION

This study provided evidence of intra- and inter-country variations in schizophrenia seasonality, especially the double-peak seasons in China. Exposure to local weather conditions mainly temperature changes and precipitation could affect the onset risk of schizophrenia.

Heatwaves and human sleep: Stress response versus adaptation

The World Meteorological Organization considers a heatwave as "a period of statistically unusual hot weather persisting for a number of days and nights". Accompanying the ongoing global climate change, sharp heatwave bouts occur worldwide, growing in frequency and intensity, and beginning earlier in the season. Heatwaves exacerbate the risk of heat-related illnesses, hence human morbidity and mortality, particularly in vulnerable elderly and children. Heat-related illnesses present a continuum from normothermic (prickly heat, heat edema, heat cramps, heat tetany) to hyperthermic syndromes (from heat syncope and heat exhaustion to lethal heat stroke). Heat stroke may occur through passive heating and/or exertional exercise. "Normal sleep", such as observed in temperate conditions, is altered during heatwaves. Brisk excessive heat bouts shorten and fragment human sleep. Particularly, deep N3 sleep (formerly slow-wave sleep) and REM sleep are depleted, such as in other stressful situations. The resultant sleep loss is deleterious to cognitive performance, emotional brain function, behavior, and susceptibility to chronic health conditions and infectious diseases. Our group has previously demonstrated that sleep constitutes an adaptive mechanism during climatic heat acclimatization. In parallel, artificial heat acclimation procedures have been proposed in sports and military activities, and for the elderly. Other preventive actions should be considered, such as education and urban heat island cooling (vegetation, white paint), thus avoiding energy-hungry air conditioning.