Review Article: Vulnerability to Heat-related Mortality: A Systematic Review, Meta-analysis, and Meta-regression Analysis

Lagged effect of ambient temperature on hospitalization for cardiovascular diseases in Wuwei, suburbs Northwest China

Studies on the effect of ambient temperature on the number of hospitalizations for cardiovascular diseases in rural Northwest China are rare, and there is a gap in related studies in Wuwei, a less developed city located in Northwest China. We collected hospitalization data from patients with cardiovascular diseases from the new Rural Cooperative Medical Insurance Scheme in Wuwei and meteorological data from the Gansu Provincial Meteorological Bureau and investigated the effect of ambient temperature on the number of hospitalizations for cardiovascular diseases in rural Wuwei, by means of distributed lag nonlinear models (DLNMs). A total of 53,642 patients with cardiovascular diseases were included from 1 January 2011, to 31 December 2015. The damaging effect of low temperature gradually increased with increasing lag time, and the damaging effect of high temperature reached its maximum on the same day (lag0); the heat effect caused more damage than the cold effect; and for both low and high temperatures, the relative risk (RR) was greater among female and elderly patients than among male and adult patients. This study may provide a theoretical basis for relevant departments to formulate meteorological policies to protect the health of susceptible people.

Brain-derived neurotrophic factor in older adults exposed to simulated indoor overheating

PURPOSE

Brain-derived neurotrophic factor (BDNF) is a neuroprotective growth factor that increases in young adults during short, intense bouts of passive heat stress. However, this may not reflect the response in heat-vulnerable populations exposed to air temperatures more consistent with indoor overheating during hot weather and heatwaves, especially as the BDNF response to acute stressors may diminish with increasing age. We therefore evaluated the ambient and body temperature-dependent responses of BDNF in older adults during daylong passive heating.

METHODS

Sixteen older adults (6 females; aged 66-78 years) completed 8-h exposure to four randomized ambient conditions simulating those experienced indoors during hot weather and heatwaves in continental climates: 22 °C (air-conditioning; control), 26 °C (health-agency-recommended indoor temperature limit), 31 °C, and 36 °C (non-airconditioned home); all 45% relative humidity. To further investigate upstream mechanisms of BDNF regulation during thermal strain, we also explored associations between BDNF and circulating heat shock protein 70 (HSP70; taken as an indicator of the heat shock response).

RESULTS

Circulating BDNF was elevated by ~ 28% (1139 [95%CI: 166, 2112] pg/mL) at end-exposure in the 36 °C compared to the 22 °C control condition (P = 0.026; 26 °C-and 31 °C-22 °C differences: P ≥ 0.090), increasing 90 [22, 158] pg/mL per 1 °C rise in ambient temperature (linear trend: P = 0.011). BDNF was also positively correlated with mean body temperatures (P = 0.013), which increased 0.12 [0.10, 0.13]°C per 1 °C rise in ambient temperature (P < 0.001). By contrast, serum HSP70 did not change across conditions (P ≥ 0.156), nor was it associated with BDNF (P = 0.376).

CONCLUSION

Our findings demonstrate a progressive increase in circulating BDNF during indoor overheating in older adults.

Heat-related impacts on all-cause emergency hospitalisation differ by area deprivation and urbanicity: a time-stratified case-crossover study in Japan

BACKGROUND

Climate-related health impacts have been a global public health concern. Identifying vulnerable populations is critical in implementing adaptation strategies. This study aimed to examine how heat-related impacts on all-cause emergency hospitalisations differ by area deprivation and urbanicity.

METHODS

All-cause emergency hospitalisations were identified in the Japanese nationwide administrative database during the warm season between 2011 and 2019. A time-stratified case-crossover study was conducted to examine short-term associations between daily mean temperature and hospitalisation. Days of heat exposure were defined as days when the daily mean temperature exceeded the minimum morbidity temperature (ie, temperature with the lowest relative risk between the 25th and the 75th percentiles of the daily mean temperature distribution). Analyses were stratified by area deprivation index and urbanicity. Heat-related excess hospitalisations were quantified using the population attributable fraction (PAF), derived as a fraction of heat-attributable emergency hospitalisations to the total number of emergency hospitalisations for all study subjects or within specific subgroups.

RESULTS

We identified 5 914 084 hospitalisations. Among all study subjects, PAF for heat-related excess hospitalisations was 1.69% (95% CI 1.54% to 1.87%). PAF for heat-related excess hospitalisations was more pronounced in people living in the most deprived areas (1.87%, 95% CI 1.68% to 2.06%) than those in the least deprived (1.19%, 95% CI 0.98% to 1.41%) and in urban populations (2.03%, 95% CI 1.78% to 2.30%) than rural ones (1.42% (95%CI 1.24% to 1.60%)). When further stratified by deprivation and urbanicity simultaneously, PAF for heat-related excess hospitalisations was most significant among urban populations living in the most deprived areas (2.62%, 95% CI 2.26% to 3.03%).

CONCLUSION

These findings revealed that individuals living in the most deprived areas in urban settings were particularly vulnerable to heat exposure. Adaptation strategies tailored to socioeconomic and geographical inequalities can potentially reduce future heat-related health impacts.

Climate Change and Cardiovascular Disease: Who Is Vulnerable?

Climate change involves a shift in earth's climate indicators over extended periods of time due to human activity. Anthropogenic air pollution has resulted in trapping heat, contributing to global warming, which contributes to worsening air pollution through facilitating oxidizing of air constituents. It is becoming more evident that the effects of climate change, such as air pollution and ambient temperatures, are interconnected with each other and other environmental factors. While the relationship between climate change components and cardiovascular disease is well documented in the literature, their interaction with one another along with individuals' biological and social risk factors is yet to be elucidated. In this review, we summarize that pathophysiological mechanisms by ambient temperatures directly affect cardiovascular health and describe the most vulnerable subgroups, defined by age, sex, race, and socioeconomic factors. Finally, we provide guidance on the importance of integrating climate, environmental, social, and health data into common platforms to inform researchers and policies.

Projecting the overall heat-related health burden and associated economic costs in a climate change context in Quebec, Canada

Extreme heat represents a major health risk for the world's population, that is amplified by climate change. However, the health costs associated with these heat events have only been little studied. To stimulate the implementation of effective interventions against extreme heat, a more comprehensive economic valuation of these health impacts is crucial. In this study, a general framework for assessing historical and projected heat-related health costs is presented and then applied to the province of Quebec (Canada). First, heat-related mortality and morbidity, as well as the number of extreme heatwaves, were computed for a historical (∼2000) and projected (∼2050) period under two shared socioeconomic pathways (SSP). Then, these heat-related numbers were converted into 1) direct healthcare costs, 2) indirect productivity costs and 3) intangible societal costs, using the best available cost information. Results showed that historical heat-related health costs were respectively 15M$, 5M$ and 3.6G$ (in 2019 Canadian dollars) annually for the direct, indirect and intangible components in Quebec, Canada. Under a middle-of-the-road scenario (SSP2-4.5), there was a 3-fold increase in total costs due to climate and population change (10.9G$ annually), while under a pessimistic scenario (SSP5-8.5), the increase was 5-fold (17.4G$). Total costs were mostly driven by intangible impacts, such as loss of life (∼90-95%) and of well-being during heatwaves (∼5-10%). Given that heat-related health costs are already significant, and likely to increase substantially in the future, this study has demonstrated the vital need to reduce its burden now and in the future by adopting more measures to mitigate climate change and adapt to heat.

Subseasonal Prediction of Heat-Related Mortality in Switzerland

Heatwaves pose a range of severe impacts on human health, including an increase in premature mortality. The summers of 2018 and 2022 are two examples with record-breaking temperatures leading to thousands of heat-related excess deaths in Europe. Some of the extreme temperatures experienced during these summers were predictable several weeks in advance by subseasonal forecasts. Subseasonal forecasts provide weather predictions from 2 weeks to 2 months ahead, offering advance planning capabilities. Nevertheless, there is only limited assessment of the potential for heat-health warning systems at a regional level on subseasonal timescales. Here we combine methods of climate epidemiology and subseasonal forecasts to retrospectively predict the 2018 and 2022 heat-related mortality for the cantons of Zurich and Geneva in Switzerland. The temperature-mortality association for these cantons is estimated using observed daily temperature and mortality during summers between 1990 and 2017. The temperature-mortality association is subsequently combined with bias-corrected subseasonal forecasts at a spatial resolution of 2-km to predict the daily heat-related mortality counts of 2018 and 2022. The mortality predictions are compared against the daily heat-related mortality estimated based on observed temperature during these two summers. Heat-related mortality peaks occurring for a few days can be accurately predicted up to 2 weeks ahead, while longer periods of heat-related mortality lasting a few weeks can be anticipated 3 to even 4 weeks ahead. Our findings demonstrate that subseasonal forecasts are a valuable-but yet untapped-tool for potentially issuing warnings for the excess health burden observed during central European summers.

Development and Validation of a Short Food Frequency Questionnaire (SH-FFQ) in Iranian Adults: A Prospective Longitudinal Study

Background

An accurate assessment of food intake is necessary to monitor nutritional status. However, differences in cultures and dietary habits between communities make it necessary to create culturally specific tools to evaluate food intake. This study aimed to develop and validate a short food frequency questionnaire (SH-FFQ) in Iranian adults.

Methods

This perspective longitudinal study was conducted during four months. A total of 135 healthy adults over 18 years (both of sex) were included. The 24-hour dietary recalls (24-HDRs) (three times per month: A total of 12 numbers) were collected as reference for validation of SH-FFQ. Participants completed two SH-FFQ, once at the end of the fourth month for validity, and the second one week after the first administration for reliability assessing.

Results

Reliability analysis showed that the mean difference between the two SH-FFQs was not statistically significant (P > 0.05). None of the correlation coefficients (rs) were less than 0.4. There was a substantial or perfect correlation (r > 0.6) in 85.1% and a moderate correlation (r = 0.4-0.6) in 14.9% of food items. For validity assessment, the average values of two SH-FFQ1 and SH-FFQ2 (SH-FFQ) were compared with the average values of 24-HDRs. All of the intraclass correlation coefficients (ICCs) of between SH-FFQ and 24-HDRs were equal to or greater than 0.4 (except one item). Moderate correlation (ICC = 0.4-0.6) and substantial or perfect correlation (ICC > 0.6) were observed in 38.3% and 59.6% of food items, respectively.

Conclusions

The current study showed that the developed SH-FFQ is reliable and valid in Iranian adults. This developed SH-FFQ can be used in nutritional assessments.

Quantifying the historical and future heat-related mortality above the heat alert thresholds of the inaugural Chinese national heat-health action plan

BACKGROUND

China published its inaugural national heat-health action plan (HHAP) in 2023, but the mortality burden associated with temperatures exceeding the heat alert thresholds specified by this HHAP (maximum temperatures >35, 37, or 40 °C) remains unknown. We aimed to estimate the historical and future mortality burden associated with temperatures above the heat alert thresholds of the Chinese national HHAP.

METHODS

We conducted time-series analyses to estimate the mortality burden associated with temperatures exceeding the three heat alert thresholds from 2016 to 2019 in Jiangsu Province (including 13 cities, population ∼80.7 million), China. A quasi-Poisson regression in conjunction with a distributed lag non-linear model was used to estimate the dose-response association between maximum temperature and mortality risk from 2016 to 2019, adjusting for potential covariates. We then projected the future mortality burden associated with temperatures exceeding these thresholds under three distinct levels of greenhouse gas (GHG) emission scenarios via scenario shared socioeconomic pathways [SSP] 1-2.6 (low), SSP2-4.5 (intermediate), and SSP5-8.5 (high), respectively, by assuming that there will be no adaptation to heat. Climate scenarios derived from the General Circulation Model (GCM) under the Coupled Model Intercomparison Project Phase 6 (CMIP6) were used.

RESULTS

From 2016 to 2019, temperatures above 35 °C were associated with 0.51% of mortality, including 0.40% associated with 35 °C-37 °C and 0.11% associated with >37 °C. Heat-related mortality risk was most prominent in those who were single/divorced/widowed and had <10 years of education. Under SSP2-4.5, compared with the 2020s, the excess mortality associated with >37 °C would increase by 1.4 times in the 2050s and 1.7 times in the 2090s. Under SSP5-8.5, the annual number of days with maximum temperature >37 °C would approximately double every 20 years (67 days annually in the 2090s). Consequently, compared with the 2020s, the excess mortality associated with >37 °C would increase by 2.8 times in the 2050s and 18.4 times in the 2090s.

CONCLUSION

Significant mortality risk is associated with temperatures above the lowest heat alert threshold of the Chinese national HHAP (35 °C). If the high GHG emission scenario occurred, the annual number of days and excess mortality associated with maximum temperatures >37 °C would largely increase in the coming decades.

The spatial distribution of heat related hospitalizations and classification of the most dangerous heat events in California at a small-scale level

Many studies have explored the impact of extreme heat on health, but few have investigated localized heat-health outcomes across a wide area. We examined fine-scale variability in vulnerable areas, considering population distribution, local weather, and landscape characteristics. Using 36 different heat event definitions, we identified the most dangerous types of heat events based on minimum, maximum, and diurnal temperatures with varying thresholds and durations. Focusing on California's diverse climate, elevation, and population distribution, we analyzed hospital admissions for various causes of admission (2004-2013). Our matching approach identified vulnerable zip codes, even with small populations, on absolute and relative scales. Bayesian Hierarchical models leveraged spatial correlation. We ranked the 36 heat event types by attributable hospital admissions per zip code and provided code, simulated data, and an interactive web app for reproducibility. Our findings showed high variation in heat-related hospitalizations in coastal cities and substantial heat burdens in the Central Valley. Diurnal heat events had the greatest impact in the Central Valley, while nighttime extreme heat events drove burdens in the southeastern desert. This spatially informed approach guides local policies, prioritizing dangerous heat events to reduce the heat-health burden. The methodology is applicable to other regions, informing early warning systems and characterizing extreme heat impacts.

Excess mortality related to high air temperature: Comparison of the periods including 1994 and 2018, the worst heat waves in the history of South Korea

Climate change has caused extreme weather events, including frequent summer heat waves. We examined how the effects of high air temperatures on mortality have changed between the two study periods (1991-1995 and 2015-2019), including 1994 and 2018, the worst heat wave years in the meteorological history of South Korea. Temperature data from the Korea Meteorological Administration and mortality data from Statistics Korea were used in this study. We used distributed lag nonlinear models to estimate the cumulative relative risks (CRRs) to determine the association between daily maximum temperature in summer (June to September) and mortality. CRRs were estimated for each province and pooled using a random-effects meta-analysis for all provinces. Maximum temperature and annual average days in heat wave were 37.7°C and 11.8 in 1991-1995 and 38.3°C and 18.8 in 2015-2019. The slope of the CRR for mortality increases with increasing temperature and has been steeper in the past than in recent years and steeper in those over 65 than in those under 65. Excess mortality has recently declined compared with that in the past. The impact of high summer temperatures on mortality changed between the two periods, suggesting improved population resilience.

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

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

Novel genomic variants related to visceral adiposity index (VAI) and body adiposity index (BAI) in Indian sib-pairs

BACKGROUND

Obesity is among the leading public health threats globally. Over the last few years, visceral adiposity index (VAI), and body adiposity index (BAI), derived from anthropometric, and biochemical measures, have gained importance as a measure of obesity. However, unlike other common indices like body mass index, and waist circumference, the genetic predisposition of VAI, and BAI under-examined.

METHODS

2265 sib-pairs from Indian Migration Study were used for examining the association of genetic variants from the Cardio-Metabochip array with VAI, and BAI. Mixed linear regression models were run, and all inferences were based on the within-sib component of the Fulker's association models. Gene-environment/lifestyle interaction analyses were also undertaken.

RESULTS

rs6659428 at LOC400796 | SEC16B (β = 0.26, SE = 0.05), and rs7611535 at DRD3 | LOC645180 (β = 0.18, SE = 0.04) were associated with VAI at suggestive significance value of <8.21 × 10-6. For BAI, rs73300702 at JAZF1-AS1 (β = 0.27, SE = 0.06), was the top hit at p value < 8.21 × 10-6. Further, rs6659428 showed marginal effect modification with rural/urban location (β = 0.26, SE = 0.13, p value = 0.047), and rs73300702 with physical activity (β = -0.29,SE = 0.14, p value = 0.034).

CONCLUSION

We report three novel genetic loci for VAI, and BAI in Indians that are important indicators of adiposity. These findings need to be replicated and validated with larger samples from different ethnicities. Further, functional studies for understanding the biological mechanisms of these adiposity indices need to be undertaken to understand the underlying pathophysiology.

Heat Waves and Adverse Health Events Among Dually Eligible Individuals 65 Years and Older

Importance

Extensive research has found the detrimental health effects of heat waves. However, a critical gap exists in understanding their association with adverse health events among older dually eligible individuals, who may be particularly susceptible to heat waves.

Objective

To assess the association between heat waves and adverse health events among dually eligible individuals 65 years and older.

Design, Setting, and Participants

This retrospective time-series study assessed the association between heat waves in warm months from 2016 to 2019 and zip code tabulation area (ZCTA)-day level adverse health events. Dually eligible individuals 65 years and older who were continuously enrolled in either a Medicare fee-for-service plan or a Medicare Advantage plan with full Medicaid benefits from May to September in any given year were identified. All ZCTAs in the US with at least 1 dually eligible individual in each study year were included. Data were analyzed from September 2023 to August 2024.

Exposure

Heat waves, defined as 3 or more consecutive extreme heat days (ie, days with a maximum temperature of at least 90 °F [32.2 °C] and in the 97th percentile of daily maximum temperatures for each ZCTA during the study period).

Main Outcomes and Measures

Daily counts of heat-related emergency department visits and heat-related hospitalizations for each ZCTA.

Results

The study sample included 5 448 499 beneficiaries 65 years and older in 28 404 ZCTAs across 50 states and Washington, DC; the mean (SD) proportion of female beneficiaries and beneficiaries 85 years and older in each ZCTA was 66% (7%) and 20% (8%), respectively. The incidence rate for heat-related emergency department visits was 10% higher during heat wave days compared to non-heat wave days (incidence rate ratio [IRR], 1.10; 95% CI, 1.08-1.12), and the incidence rate of heat-related hospitalizations was 7% higher during heat wave days (IRR, 1.07; 95% CI, 1.04-1.09). There were similar patterns in other adverse health events, including a 4% higher incidence rate of death during heat wave days (IRR, 1.04; 95% CI, 1.01-1.07). The magnitude of these associations varied across some subgroups. For example, the association between heat waves and heat-related emergency department visits was statistically significant only for individuals in 3 of 9 US climate regions: the Northwest, Ohio Valley, and the West.

Conclusions and Relevance

In this time-series study, heat waves were associated with increased adverse health events among dually eligible individuals 65 years and older. Without adaptation strategies to address the health-related impacts of heat, dually eligible individuals are increasingly likely to face adverse outcomes.

Mortality in extreme heat events: an analysis of Los Angeles County Medical Examiner data

OBJECTIVES

Climate change is intensifying heat events, and local governments are working to absorb and mitigate the associated costs. To develop effective responses, local data on the relationship between climate and health are crucial. This study investigates the impact of heat events on unexpected mortality, focusing on deaths investigated by the Medical Examiner in Los Angeles County.

STUDY DESIGN

A retrospective observational study.

METHODS

We estimate the associations between the National Weather Service's HeatRisk index and deaths investigated by the Medical Examiner in Los Angeles County using negative binomial count models with controls for time trends and seasonality. In subgroup analyses, we explore how these effects vary for those who are homeless or living in care facilities.

RESULTS

Compared to days with no HeatRisk, days with moderate, major, or extreme HeatRisk were associated with death increases of 6.7% [CI: 1.9-11.7%], 15.3% [CI: 2.9-29.1%], and 65.5% [CI: 34.9-102.1%], respectively. Effects were more pronounced for individuals who were homeless or in care facilities. Major or extreme heat days were associated with a 59.3% [CI: 19.8-109.4%] increase in deaths among homeless individuals and a 91.4% [CI: 19.0-198.6%] increase in deaths among those in care facilities.

CONCLUSIONS

Heat events have a significant impact on mortality investigated by the Medical Examiner, especially among vulnerable groups. Local governments may consider using the warning tools provided by the National Weather Service to focus their resources on the most intense heat events, especially to target those living in care facilities or who are homeless.

Risk, Attributable Fraction and Attributable Number of Cause-Specific Heat-Related Emergency Hospital Admissions in Switzerland

Objectives

We assessed the relationship between heat and emergency hospital admissions (EHAs) in Switzerland using clinically relevant metrics.

Methods

Applying distributed lag non-linear models, we investigated temperature-admission associations between May and September 1998-2019 for various disease groups, by age class and gender. We estimated the relative risk (RR) for moderate (29°C) and extreme (34°C) daily maximum temperatures relative to disease-specific optimum temperature, and calculated attributable fractions (AFs) for hot days and the following week. We also calculated the total number of heat-related EHAs.

Results

We attributed 31,387 (95% confidence interval: 21,567-40,408) EHAs to above-optimal temperatures, 1.1% (0.7%-1.4%) of the total. Extreme temperatures increased the EHA risk for mental, infectious and neurological diseases. We observed particularly high AFs due to extreme heat for dehydration (85.9%, 95% CI: 82.4%-88.8%) and acute kidney injury (AKI, 56.1%, 95% CI: 45.3%-64.7%). While EHA risk generally increased with age, we also found high RRs for infectious diseases in children (0-15 years) and AKI in young adults (15-64 years).

Conclusion

Hot weather increases the EHA risk in Switzerland. Therefore a comprehensive clinical and public health response is needed.

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

Background

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

Methods

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

Results

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

Conclusions

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

Spatiotemporal Facility-Level Patterns of Summer Heat Exposure, Vulnerability, and Risk in United States Prison Landscapes

Heat is associated with increased risk of morbidity and mortality. People who are incarcerated are especially vulnerable to heat exposure due to demographic characteristics and their conditions of confinement. Evaluating heat exposure in prisons, and the characteristics of exposed populations and prisons, can elucidate prison-level risk to heat exposure. We leveraged a high-resolution air temperature data set to evaluate short and long-term patterns of heat metrics for 1,614 prisons in the United States from 1990 to 2023. We found that the most heat-exposed facilities and states were mostly in the Southwestern United States, while the prisons with the highest temperature anomalies from the historical record were in the Pacific Northwest, the Northeast, Texas, and parts of the Midwest. Prisons in the Pacific Northwest, the Northeast, and upper Midwest had the highest occurrences of days associated with an increased risk of heat-related mortality. We also estimated differences in heat exposure at prisons by facility and individual-level characteristics. We found higher proportions of non-white and Hispanic populations in the prisons with higher heat exposure. Lastly, we found that heat exposure was higher in prisons with any of nine facility-level characteristics that may modify risk to heat. This study brings together distinct measures of exposure, vulnerability, and risk, which would each inform unique strategies for heat-interventions. Community leaders and policymakers should carefully consider which measures they want to apply, and include the voices of directly impacted people, as the differing metrics and perspectives will have implications for who is included in fights for environmental justice.

Identifying groups at-risk to extreme heat: Intersections of age, race/ethnicity, and socioeconomic status

Anthropogenic climate change has resulted in a significant rise in extreme heat events, exerting considerable but unequal impacts on morbidity and mortality. Numerous studies have identified inequities in heat exposure across different groups, but social identities have often been viewed in isolation from each other. Children (5 and under) and older adults (65 and older) also face elevated risks of heat-related health impacts. We employ an intersectional cross-classificatory approach to analyze the distribution of heat exposure between sociodemographic categories split into age groups in the contiguous US. We utilize high-resolution daily air temperature data to establish three census tract-level heat metrics (i.e., average summer temperature, heat waves, and heat island days). We pair those metrics with American Community Survey estimates on racial/ethnic, socioeconomic, and disability status by age to calculate population weighted mean exposures and absolute disparity metrics. Our findings indicate few substantive differences between age groups overall, but more substantial differences between sociodemographic categories within age groups, with children and older adults from socially marginalized backgrounds facing greater exposure than adults from similar backgrounds. When looking at sociodemographic differences by age, people of color of any age and older adults without health insurance emerge as the most exposed groups. This study identifies groups who are most exposed to extreme heat. Policy and program interventions aimed at reducing the impacts of heat should take these disparities in exposure into account to achieve health equity objectives.

Methodological Approaches for Measuring the Association Between Heat Exposure and Health Outcomes: A Comprehensive Global Scoping Review

OBJECTIVE

To synthesize the methodologies of studies that evaluate the impacts of heat exposure on morbidity and mortality.

METHODS

Embase, MEDLINE, Web of Science, and Scopus were searched from date of inception until 1 March 2023 for English language literature on heat exposure and health outcomes. Records were collated, deduplicated and screened, and full texts were reviewed for inclusion and data abstraction. Eligibility for inclusion was determined as any article with climate-related heat exposure and an associated morbidity/mortality outcome.

RESULTS

Of 13,136 records initially identified, 237 articles were selected for analysis. The scope of research represented 43 countries, with most studies conducted in China (62), the USA (44), and Australia (16). Across all studies, there were 141 unique climate data sources, no standard threshold for extreme heat, and 200 unique health outcome data sources. The distributed lag non-linear model (DLNM) was the most common analytic method (48.1% of studies) and had high usage rates in China (68.9%) and the USA (31.8%); Australia frequently used conditional logistic regression (50%). Conditional logistic regression was most prevalent in case-control studies (5 of 8 studies, 62.5%) and in case-crossover studies (29 of 70, 41.4%). DLNMs were most common in time series studies (64 of 111, 57.7%) and ecological studies (13 of 20, 65.0%).

CONCLUSIONS

This review underscores the heterogeneity of methods in heat impact studies across diverse settings and provides a resource for future researchers. Underrepresentation of certain countries, health outcomes, and limited data access were identified as potential barriers.

Unequal distributions of crowdsourced weather data in England and Wales

Personal weather stations (PWS) can provide useful data on urban climates by densifying the number of weather measurements across major cities. They do so at a lower cost than official weather stations by national meteorological services. Despite the increasing use of PWS data, little attention has yet been paid to the underlying socio-economic and environmental inequalities in PWS coverage. Using social deprivation, demographic, and environmental indicators in England and Wales, we characterize existing inequalities in the current coverage of PWS. We find that there are fewer PWS in more deprived areas which also observe higher proportions of ethnic minorities, lower vegetation coverage, higher building height and building surface fraction, and lower proportions of inhabitants under 65 years old. This implies that data on urban climate may be less reliable or more uncertain in particular areas, which may limit the potential for climate adaptation and empowerment in those communities.

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.

Composition of factors for local heat adaptation measures at the local level in cities of the mid-latitude - An approach for the south-west of Germany

Traditional heat health warning systems focus on severe and extreme heat events at the district or regional level, often overlooking localized risk and protective factors such as healthcare access and urban green spaces. This approach considers less the varying impacts of heat within cities, including the phenomenon of Urban Heat Islands (UHIs) and the diverse needs of different populations. To address these shortcomings, a need for the development of an Urban Heat Health Warning and Information System (UHHWIS) that operates within the framework of Heat Health Action Plans is needed. Such a system integrates national acute heat health warnings with city-specific assessments of UHI effects and other relevant factors. The technical implementation of the UHHWIS involves the calculation and preprocessing of basic factors such as the Normalised Difference Vegetation Index (NDVI), imperviousness, and UHI intensity. Additionally, further factors are assessed, spatially processed, and provided in accordance with Open Geospatial Consortium (OGC) standards. An iso-area analysis is conducted to evaluate the accessibility of protective factors, such as urban green spaces, drinking wells, hospitals, physicians, and pharmacies, based on the city's road topology. One crucial factor considered in the system is the casting of shadows, which is influenced by both time and location and facilitated through deck.gl. The developed template encompasses all these components into a unified system aimed at protecting vulnerable and risk groups, such as the elderly, through resilient, climate-adapted urban planning. The system provides warnings and information tailored to the urban morphology and prevailing conditions, complemented by a catalogue of potential short- to long-term measures focused on behavioral changes and climate-resilient urban planning strategies. The template can be adapted for use in various European cities, offering valuable insights to decision-makers in city administration for mitigating thermal stress and enhancing resilience against urban heat nowadays and in future.

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

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

Socio-environmental modifiers of heat-related mortality in eight Swiss cities: A case time series analysis

In the light of growing urbanization and projected temperature increases due to climate change, heat-related mortality in urban areas is a pressing public health concern. Heat exposure and vulnerability to heat may vary within cities depending on structural features and socioeconomic factors. This study examined the effect modification of the temperature-mortality association of three socio-environmental factors in eight Swiss cities and population subgroups (<75 and ≥ 75 years, males, females): urban heat islands (UHI) based on within-city temperature contrasts, residential greenness measured as normalized difference vegetation index (NDVI) and neighborhood socioeconomic position (SEP). We used individual death records from the Swiss National Cohort occurring during the warm season (May to September) in the years 2003-2016. We performed a case time series analysis using conditional quasi-Poisson and distributed lag non-linear models with a lag of 0-3 days. As exposure variables, we used daily maximum temperatures (Tmax) and a binary indicator for warm nights (Tmin ≥20 °C). In total, 53,593 deaths occurred during the study period. Overall across the eight cities, the mortality risk increased by 31% (1.31 relative risk (95% confidence interval: 1.20-1.42)) between 22.5 °C (the minimum mortality temperature) and 35 °C (the 99th percentile) for warm-season Tmax. Stratified analysis suggested that the heat-related risk at 35 °C is 26% (95%CI: -4%, 67%) higher in UHI compared to non-UHI areas. Indications of smaller risk differences were observed between the low vs. high greenness strata (Relative risk difference = 13% (95%CI: -11%; 44%)). Living in low SEP neighborhoods was associated with an increased heat related risk in the non-elderly population (<75 years). Our results indicate that UHI are associated with increased heat-related mortality risk within Swiss cities, and that features beyond greenness are responsible for such spatial risk differences.

The relationship between hot temperatures and hospital admissions for psychosis in adults diagnosed with schizophrenia: A case-crossover study in Quebec, Canada

INTRODUCTION

Some studies have found hot temperatures to be associated with exacerbations of schizophrenia, namely psychoses. As climate changes faster in Northern countries, our understanding of the association between temperature and hospital admissions (HA) for psychosis needs to be deepened.

OBJECTIVES

1) Among adults diagnosed with schizophrenia, measure the relationship between mean temperatures and HAs for psychosis during summer. 2) Determine the influence of individual and ecological characteristics on this relationship.

METHODS

A cohort of adults diagnosed with schizophrenia (n = 30,649) was assembled using Quebec's Integrated Chronic Disease Surveillance System (QICDSS). The follow-up spanned summers from 2001 to 2019, using hospital data from the QICDSS and meteorological data from the National Aeronautics and Space Administration's (NASA) Daymet database. In four geographic regions of the province of Quebec, a conditional logistic regression was used for the case-crossover analysis of the relationship between mean temperatures (at lags up to 6 days) and HAs for psychosis using a distributed lag non-linear model (DLNM). The analyses were adjusted for relative humidity, stratified according to individual (age, sex, and comorbidities) and ecological (material and social deprivation index and exposure to green space) factors, and then pooled through a meta-regression.

RESULTS

The statistical analyses revealed a statistically significant increase in HAs three days (lag 3) after elevated mean temperatures corresponding to the 90th percentile relative to a minimum morbidity temperature (MMT) (OR 1.040; 95% CI 1.008-1.074), while the cumulative effect over six days was not statistically significant (OR 1.052; 95% IC 0.993-1.114). Stratified analyses revealed non statistically significant gradients of increasing HAs relative to increasing material deprivation and decreasing green space levels.

CONCLUSIONS

The statistical analyses conducted in this project showed the pattern of admissions for psychosis after hot days. This finding could be useful to better plan health services in a rapidly changing climate.

Global supply chains amplify economic costs of future extreme heat risk

Evidence shows a continuing increase in the frequency and severity of global heatwaves1,2, raising concerns about the future impacts of climate change and the associated socioeconomic costs3,4. Here we develop a disaster footprint analytical framework by integrating climate, epidemiological and hybrid input-output and computable general equilibrium global trade models to estimate the midcentury socioeconomic impacts of heat stress. We consider health costs related to heat exposure, the value of heat-induced labour productivity loss and indirect losses due to economic disruptions cascading through supply chains. Here we show that the global annual incremental gross domestic product loss increases exponentially from 0.03 ± 0.01 (SSP 245)-0.05 ± 0.03 (SSP 585) percentage points during 2030-2040 to 0.05 ± 0.01-0.15 ± 0.04 percentage points during 2050-2060. By 2060, the expected global economic losses reach a total of 0.6-4.6% with losses attributed to health loss (37-45%), labour productivity loss (18-37%) and indirect loss (12-43%) under different shared socioeconomic pathways. Small- and medium-sized developing countries suffer disproportionately from higher health loss in South-Central Africa (2.1 to 4.0 times above global average) and labour productivity loss in West Africa and Southeast Asia (2.0-3.3 times above global average). The supply-chain disruption effects are much more widespread with strong hit to those manufacturing-heavy countries such as China and the USA, leading to soaring economic losses of 2.7 ± 0.7% and 1.8 ± 0.5%, respectively.

Surviving indoor heat stress in United States: A comprehensive review exploring the impact of overheating on the thermal comfort, health, and social economic factors of occupants

In the face of escalating global climate change and the increasing frequency of extreme heat events, the mitigation of building overheating has become an urgent priority. This comprehensive review converges insights from building science and public health domains to offer a thorough understanding of the multifaceted impacts of indoor overheating on occupants. The paper addresses a significant research gap by offering a holistic exploration of indoor overheating of residential buildings and its consequences, with a specific focus on the United States, an economically diverse nation that has been underrepresented in the literature. The review illuminates the effects of overheating on thermal comfort, health, and socio-economic aspects within the built environment. It emphasizes associated repercussions, including heightened cooling energy consumption, increased peak electricity demand, and elevated vulnerability, leading to exacerbated heat-related mortality and morbidity rates, especially among disadvantaged groups. The study concludes that vulnerabilities to these impacts are intricately tied to regional climatic conditions, highlighting the inadequacy of a one-size-fits-all approach. Tailored interventions for each climate zone are deemed necessary, considering the consistent occurrence of indoor temperatures surpassing outdoor levels, known as superheating, which poses distinct challenges. The research underscores the urgency of addressing indoor overheating as a critical facet of public health, acknowledging direct socioeconomic repercussions. It advocates for further research to inform comprehensive policies that safeguard public health across diverse indoor environments.

Impact of ambient temperature on respiratory disease: a case-crossover study in Seoul

BACKGROUND

Respiratory diseases contribute to global morbidity and mortality, and temperature is a significant factor. We investigated the association between ambient temperature and emergency department (ED) visits for various respiratory diseases in Seoul, South Korea.

METHODS

Using data from the National Emergency Department Information System (2008-2017), we analysed 1,616,644 ED visits for respiratory diseases, categorised according to the Korean Standard Classification of Diseases 7th revision codes (J00-J99). Using a time-stratified case-crossover design and a distributed lag nonlinear model, we investigated the effect of temperature exposure on ED visits for respiratory diseases, calculating the relative risk (RR) for the maximum risk temperature (MaxRT) of both cold and hot extremes compared to the minimum risk temperature (MinRT).

RESULTS

Cold temperatures (MaxRT: -9.0 °C) resulted in a 2.68-fold increase (RR = 2.68, 95% CI = 2.26-3.14) in ED visits for total respiratory diseases, while hot temperatures (MaxRT: 29.4 °C) led to a 1.26-fold increase (RR = 1.26, 95% CI = 1.11-1.42) compared to the MinRT (24.8 °C). Cold temperatures increased the risk of most respiratory diseases, except interstitial lung disease, whereas hot temperatures increased ED visits for acute upper respiratory infections and influenza. Cold temperatures increased ED visits for all age groups, especially those aged 18-64 (RR = 3.54, 95% CI = 2.90-4.33), while hot temperatures significantly affected those < 18 (RR = 1.45, 95% CI = 1.27-1.66). The risk levels were similar in both males and females, regardless of hot and cold temperatures.

CONCLUSION

Our findings underscore the significant impact of both cold and heat exposure on ED visits for respiratory diseases, with varying intensities and risk profiles across different population groups.

The role of older adult-focused social vulnerability on the relationship between temperature and emergency department attendance in a subtropical Asian city

PURPOSE

Older adults exhibit a wide range of capabilities and vulnerabilities that affect their capacity to respond to heat. This study analysed the associations between hot temperatures and Accident & Emergency (A&E) attendance taking into account older adult-focused social vulnerability.

METHODS

Daily A&E attendance data of Young-old (65-74) and Old-old (75+) was obtained for Hong Kong 2010-2019 hot seasons and stratified into three Social Vulnerability Index (SVI) groups (Low, Moderate, High). Mean temperature (lag 0-2) was analysed on A&E attendance at each SVI using Generalized Additive Models and Distributed Lag Non-linear Models.

RESULTS

High temperatures were associated with increased same-day (lag 0) relative risk (RR) of A&E attendance for Young-old and Old-old in High SVI districts, with RR being 1.024 (95 % CI: 1.011, 1.037) and 1.036 (95 % CI: 1.018, 1.053), respectively. The Old-old living in Moderate and Low SVI districts also demonstrated increased RR of 1.037 (95 % CI: 1.028, 1.047) and 1.022 (95 % CI: 1.009, 1.036), respectively. Fewer emergency visits were found on the subsequent day (lag 1) of hot temperatures.

CONCLUSIONS

Older adults, both young-old and old-old, living in districts with higher social vulnerability tended to have increased risk of A&E attendance associated with same-day high temperature. With climate change and rapidly aging population, cities should prepare to meet needs of more vulnerable older adults in extreme heat.

Spatial contrasts and temporal changes in fine-scale heat exposure and vulnerability in the Paris region

Heat is identified as a key climate risk in Europe. Vulnerability to heat can be aggravated by enhanced exposure (e.g., urban heat island), individual susceptibility (e.g., age, income), and adaptive capacity (e.g., home ownership, presence of vegetation). We investigated the spatial and temporal patterns of the environmental and social drivers of vulnerability to heat in the Paris region, France, over the 2000-2020 period, and their association with mortality (restricted to 2000-2017). Daily temperatures were modeled for the 5265 IRIS of the Paris region for 2000-2020. Annual land use and socioeconomic data were collected for each IRIS. They were used to identify a priori five classes of heat-vulnerable areas based on a cluster analysis. The temperature-mortality relationship was investigated using a time-series approach stratified by clusters of vulnerability. The Paris region exhibited a strong urban heat island effect, with a marked shift in temperature distributions after 2015. The clustering suggested that the most heat-vulnerable IRIS in the Paris region have a high or very high exposure to temperature in a highly urbanized environment with little vegetation, but are not systematically associated with social deprivation. A similar J-shape temperature-mortality relationship was observed in the five clusters. Between 2000 and 2017, around 8000 deaths were attributable to heat, 5600 of which were observed in the most vulnerable clusters. Vulnerability assessments based on geographical indicators are key tools for urban planners and decision-makers. They complement the knowledge about individual risk factors but should be further evaluated through interdisciplinary collaborations.

Valuing mortality attributable to present and future temperature extremes in Argentina

This study analyzes the weather-related health damage of present and future extreme temperatures in Argentina. Focusing on mortality, short-term impacts of temperature are obtained by regressing monthly mortality rates on inter-annual monthly weather variability. For this purpose, a countrywide panel dataset at the municipal level was constructed from the universe of deaths between 2010 and 2019, and daily meteorological records from the ERA5 weather dataset. Then, NASA Earth Exchange Global Daily Downscaled Projections (NEX-GDDP) are used to project future mortality by 2085 under two climate scenarios. Finally, present and future mortality-related economic damages are assessed using the Value of a Statistical Life. The results show that one additional day of extreme temperatures increase all-cause mortality rates relative to mild weather and that the impact of hotter-than-average temperatures is greater in magnitude than that of colder ones. Substantial heterogeneity exists between causes of death and age groups, with older people facing greater risks, while the results for gender are inconclusive. All days of extreme cold in a year generate damage equivalent to 0.64% of GDP, while heat damage is 0.11% of GDP. The total damage by extreme temperatures adds up to 0.75% of the 2019 GDP. When future temperatures are valued, the total damage increases by an additional 1.45% under scenario RCP8.5 because the lower mortality occurring on cold days only partially offsets the increase in the number of hot days. On the contrary, if temperature changes were to be mild (i.e., under scenario RCP4.5), overall mortality would be lower at the national level and the corresponding damages would decrease by 0.02%.

An Improved New YOLOv7 Algorithm for Detecting Building Air Conditioner External Units from Street View Images

Street view images are emerging as new street-level sources of urban environmental information. Accurate detection and quantification of urban air conditioners is crucial for evaluating the resilience of urban residential areas to heat wave disasters and formulating effective disaster prevention policies. Utilizing street view image data to predict the spatial coverage of urban air conditioners offers a simple and effective solution. However, detecting and accurately counting air conditioners in complex street-view environments remains challenging. This study introduced 3D parameter-free attention and coordinate attention modules into the target detection process to enhance the extraction of detailed features of air conditioner external units. It also integrated a small target detection layer to address the challenge of detecting small target objects that are easily missed. As a result, an improved algorithm named SC4-YOLOv7 was developed for detecting and recognizing air conditioner external units in street view images. To validate this new algorithm, we extracted air conditioner external units from street view images of residential buildings in Guilin City, Guangxi Zhuang Autonomous Region, China. The results of the study demonstrated that SC4-YOLOv7 significantly improved the average accuracy of recognizing air conditioner external units in street view images from 87.93% to 91.21% compared to the original YOLOv7 method while maintaining a high speed of image recognition detection. The algorithm has the potential to be extended to various applications requiring small target detection, enabling reliable detection and recognition in real street environments.

Experiences of poverty amongst low-income older adults living in a high-income country: A qualitative study

AIM

To understand the experience of low-income older adults living in poverty in a high-income country.

DESIGN

A qualitative study based on Gadamer's hermeneutic phenomenology.

METHODS

A convenience sample of twenty-seven low-income older adults were interviewed in-depth between September 2021 and January 2022. Fleming's method for conducting phenomenological qualitative studies was followed and ATLAS.ti software was used for data analysis.

RESULTS

Three main themes were extracted from the analysis: (i) 'living in the shadow of poverty', (ii) 'unprotected by the 'social shield' of the welfare state' (iii) 'the struggle to attain good health'.

CONCLUSION

Living in poverty affects all spheres of life. Older adults living in poverty feel excluded from social support policies and laws. This has a negative impact on the older adults' mental health and can lead to social isolation.

IMPLICATIONS FOR THE PROFESSION AND/OR PATIENT CARE

Nursing interventions to promote health amongst older adults living in poverty should include an assessment of the patient's social determinants and a focus on increasing social participation. Older people living in poverty experience difficulties accessing formal social support so nurses should implement patient navigation interventions that aim to help them overcome the complexities of the system. Nursing interventions to improve mental health amongst older adults living in poverty are much needed.

IMPACT

Living in poverty increases older adults' vulnerability. Older adults living in poverty suffer from mental health issues as they live under constant pressure to meet their basic needs and lack formal social support. These findings are important for nurses, who play a pivotal role in the design, implementation and evaluation of policies and interventions that promote health equity.

REPORTING METHOD

The study has been conducted following the COREQ guidelines.

PATIENT OR PUBLIC CONTRIBUTION

There has been no public or patient involvement in the design or development of the study.

Future temperature-related excess mortality under climate change and population aging scenarios in Canada

OBJECTIVE

Climate change is expected to increase global temperatures. How temperature-related mortality risk will change is not completely understood, and how future demographic changes will affect temperature-related mortality needs to be clarified. We evaluate temperature-related mortality across Canada until 2099, accounting for age groups and scenarios of population growth.

METHODS

We used daily counts of non-accidental mortality for 2000 to 2015 for all 111 health regions across Canada, incorporating in the study both urban and rural areas. A two-part time series analysis was used to estimate associations between mean daily temperatures and mortality. First, current and future daily mean temperature time series simulations were developed from Coupled Model Inter-Comparison Project 6 (CMIP6) climate model ensembles from past and projected climate change scenarios under Shared Socioeconomic Pathways (SSPs). Next, excess mortality due to heat and cold and the net difference were projected to 2099, also accounting for different regional and population aging scenarios.

RESULTS

For 2000 to 2015, we identified 3,343,311 non-accidental deaths. On average, a net increase of 17.31% (95% eCI: 13.99, 20.62) in temperature-related excess mortality under a higher greenhouse gas emission scenario is expected for Canada in 2090-2099, which represents a greater burden than a scenario that assumed strong levels of greenhouse gas mitigation policies (net increase of 3.29%; 95% eCI: 1.41, 5.17). The highest net increase was observed among people aged 65 and over, and the largest increases in both net and heat- and cold-related mortality were observed in population scenarios that incorporated the highest rates of aging.

CONCLUSION

Canada may expect net increases in temperature-related mortality under a higher emissions climate change scenario, compared to one assuming sustainable development. Urgent action is needed to mitigate future climate change impacts.

Assessing heat effects on respiratory mortality and location characteristics as modifiers of heat effects at a small area scale in Central-Northern Europe

Background

Heat effects on respiratory mortality are known, mostly from time-series studies of city-wide data. A limited number of studies have been conducted at the national level or covering non-urban areas. Effect modification by area-level factors has not been extensively investigated. Our study assessed the heat effects on respiratory mortality at a small administrative area level in Norway, Germany, and England and Wales, in the warm period (May-September) within 1996-2018. Also, we examined possible effect modification by several area-level characteristics in the framework of the EU-Horizon2020 EXHAUSTION project.

Methods

Daily respiratory mortality counts and modeled air temperature data were collected for Norway, Germany, and England and Wales at a small administrative area level. The temperature-mortality association was assessed by small area-specific Poisson regression allowing for overdispersion, using distributed lag non-linear models. Estimates were pooled at the national level and overall using a random-effect meta-analysis. Age- and sex-specific models were also applied. A multilevel random-effects model was applied to investigate the modification of the heat effects by area-level factors.

Results

A rise in temperature from the 75th to 99th percentile was associated with a 27% (95% confidence interval [CI] = 19%, 34%) increase in respiratory mortality, with higher effects for females. Increased population density and PM2.5 concentrations were associated with stronger heat effects on mortality.

Conclusions

Our study strengthens the evidence of adverse heat effects on respiratory mortality in Northern Europe by identifying vulnerable subgroups and subregions. This may contribute to the development of targeted policies for adaptation to climate change.

Are people interested in receiving advice from their general practitioner on how to protect their health during heatwaves? A survey of the German population

OBJECTIVE

Climate change increases the frequency, intensity and length of heatwaves, which puts a particular strain on the health of vulnerable population groups. General practitioners (GPs) could reach these people and provide advice on protective health behaviour against heat. Data is lacking on whether and what topic of GP advice people are interested in, and whether specific person characteristics are associated with such interests.

DESIGN

Cross-sectional, nationwide, face-to-face household survey, conducted during winter 2022/2023.

SETTING

Germany.

PARTICIPANTS

Population-based sample of 4212 respondents (aged 14-96 years), selected by using multistratified random sampling (50%) combined with multiquota sampling (50%).

MAIN OUTCOME MEASURE

Interest in receiving GP advice on health protection during heatwaves (yes/no), and the topic people find most important (advice on drinking behaviour, nutrition, cooling, cooling rooms, physical activity or medication management). Associations between predefined person characteristics and the likelihood of interest were estimated using adjusted logistic regressions.

RESULTS

A total of 4020 respondents had GP contact and provided data on the outcome measure. Of these, 23% (95% CI=22% to 25%) expressed interest in GP advice. The likelihood of expressing interest was positively associated with being female, older age (particularly those aged 75+ years: 38% were interested), having a lower level of educational attainment, having a migration background, living in a more urban area, and living in a single-person household. It was negatively associated with increasing income. Advice on medication management received highest interest (25%).

CONCLUSIONS

During winter season 2022/2023, around one quarter of the German population with GP contact-and around 40% of those aged 75+ years-was estimated to have a stated interest in receiving GP advice on protective health behaviour during heatwaves, especially on medication management. Climate change is creating new demands for healthcare provision in general practice. This study provides initial relevant information for research and practice aiming to address these demands.

Analysis of compound health impacts of heatwave and COVID-19 in Korea from May to September in 2020

The number of non-accidental deaths and heat-related illnesses due to the co-occurrence of heatwaves and COVID-19 has been identified to estimate compound health impacts between two risks. We have analyzed data from historical years (2013-2019) to calculate the baseline values of the number of non-accidental deaths and heat-related illness patients from May to September using a quasi-Poisson generalized linear model and compared them to data from 2020 in Korea. We also assessed the relative risk and absolute cumulative number of non-accidental deaths and heat-related illnesses in the summer of 2020 in Seoul, Daegu, and Gyeongnam region of Korea. In the Summer of 2020, Korea experienced 0.8% of non-accidental excess deaths, with the highest in August, and 46% of reduction was observed in heat-related throughout the study period, except in Daegu, where excess of heat-related illness occurred in August. The relative risk (RR) of non-accidental deaths at 33.1 °C, was 1.00 (CI 0.99-1.01) and 1.04 (CI 1.02-1.07) in 2013-2019 and 2020, respectively. The RR of heat-related illness at 33.1 °C, was 1.44 (CI 1.42-1.45) and 1.59 (CI 1.54-1.64) in 2013-2019 and 2020, respectively. The absolute cumulative trends of non-accidental deaths and heat-related illnesses were similar in the three regions, indicating increased non-accidental deaths and decreased heat-related illnesses at similar temperatures in 2020. During the COVID-19 pandemic, the fear of infection by the virus and the limited access to healthcare services led to changes in health-seeking behaviors. These results indicate social distancing could have had adverse impacts on other health conditions. A comprehensive health risk assessment is important when facing simultaneous risks, such as heatwaves and pandemics, in the implementation of effective countermeasures.

Assessment of short-term heat effects on cardiovascular mortality and vulnerability factors using small area data in Europe

BACKGROUND

Short-term associations between heat and cardiovascular disease (CVD) mortality have been examined mostly in large cities. However, different vulnerability and exposure levels may contribute to spatial heterogeneity. This study assessed heat effects on CVD mortality and potential vulnerability factors using data from three European countries, including urban and rural settings.

METHODS

We collected daily counts of CVD deaths aggregated at the small-area level in Norway (small-area level: municipality), England and Wales (lower super output areas), and Germany (district) during the warm season (May-September) from 1996 to 2018. Daily mean air temperatures estimated by spatial-temporal models were assigned to each small area. Within each country, we applied area-specific Quasi-Poisson regression using distributed lag nonlinear models to examine the heat effects at lag 0-1 days. The area-specific estimates were pooled by random-effects meta-analysis to derive country-specific and overall heat effects. We examined individual- and area-level heat vulnerability factors by subgroup analyses and meta-regression, respectively.

RESULTS

We included 2.84 million CVD deaths in analyses. For an increase in temperature from the 75th to the 99th percentile, the pooled relative risk (RR) for CVD mortality was 1.14 (95% CI: 1.03, 1.26), with the country-specific RRs ranging from 1.04 (1.00, 1.09) in Norway to 1.24 (1.23, 1.26) in Germany. Heat effects were stronger among women [RRs (95% CIs) for women and men: 1.18 (1.08, 1.28) vs. 1.12 (1.00, 1.24)]. Greater heat vulnerability was observed in areas with high population density, high degree of urbanization, low green coverage, and high levels of fine particulate matter.

CONCLUSION

This study provides evidence for the heat effects on CVD mortality in European countries using high-resolution data from both urban and rural areas. Besides, we identified individual- and area-level heat vulnerability factors. Our findings may facilitate the development of heat-health action plans to increase resilience to climate change.

Rapid increase in the risk of heat-related mortality

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

Nationwide projections of heat- and cold-related mortality impacts under various climate change and population development scenarios in Switzerland

Climate change and progressive population development (i.e., ageing and changes in population size) are altering the temporal patterns of temperature-related mortality in Switzerland. However, limited evidence exists on how current trends in heat- and cold-related mortality would evolve in future decades under composite scenarios of global warming and population development. Moreover, the contribution of these drivers to future mortality impacts is not well-understood. Therefore, we aimed to project heat- and cold-related mortality in Switzerland under various combinations of emission and population development scenarios and to disentangle the contribution of each of these two drivers using high-resolution mortality and temperature data. We combined age-specific (<75 and ⩾75 years) temperature-mortality associations in each district in Switzerland (1990-2010), estimated through a two-stage time series analysis, with 2 km downscaled CMIP5 temperature data and population and mortality rate projections under two scenarios: RCP4.5/SSP2 and RCP8.5/SSP5. We derived heat and cold-related mortality for different warming targets (1.5 °C, 2.0 °C and 3.0 °C) using different emission and population development scenarios and compared this to the baseline period (1990-2010). Heat-related mortality is projected to increase from 312 (116; 510) in the 1990-2010 period to 1274 (537; 2284) annual deaths under 2.0 °C of warming (RCP4.5/SSP2) and to 1871 (791; 3284) under 3.0 °C of warming (RCP8.5/SSP5). Cold-related mortality will substantially increase from 4069 (1898; 6016) to 6558 (3223; 9589) annual deaths under 2.0 °C (RCP4.5/SSP2) and to 5997 (2951; 8759) under 3.0 °C (RCP8.5/SSP5). Moreover, while the increase in cold-related mortality is solely driven by population development, for heat, both components (i.e., changes in climate and population) have a similar contribution of around 50% to the projected heat-related mortality trends. In conclusion, our findings suggest that both heat- and cold-related mortality will substantially increase under all scenarios of climate change and population development in Switzerland. Population development will lead to an increase in cold-related mortality despite the decrease in cold temperature under warmer scenarios. Whereas the combination of the progressive warming of the climate and population development will substantially increase and exacerbate the total temperature-related mortality burden in Switzerland.

The Direct and Indirect Influences of Interrelated Regional-Level Sociodemographic Factors on Heat-Attributable Mortality in Europe: Insights for Adaptation Strategies

BACKGROUND

Heat is a significant cause of mortality, but impact patterns are heterogenous. Previous studies assessing such heterogeneity focused exclusively on risk rather than heat-attributable mortality burdens and assume predictors are independent.

OBJECTIVES

We assessed how four interrelated regional-level sociodemographic predictors-education, life expectancy, the ratio of older to younger people (aging index), and relative income-influence heterogeneity in heat-attributable mortality burdens in Europe and then derived insights into adaptation strategies.

METHODS

We extracted four outcomes from a temperature-mortality study covering 16 European countries: the rate of increase in mortality risk at moderate and extreme temperatures (moderate and extreme slope, respectively), the minimum mortality temperature percentile (MMTP), and the underlying mortality rate. We used structural equation modeling with country-level random effects to quantify the direct and indirect influences of the predictors on the outcomes.

RESULTS

Higher levels of education were directly associated with lower heat-related mortality at moderate and extreme temperatures via lower slopes and higher MMTPs. A one standard deviation increase in education was associated with a - 0.46 ± 0.14 , - 0.41 ± 0.12 , and 0.41 ± 0.12 standard deviation (± standard error ) change in the moderate slope, extreme slope, and MMTP, respectively. However, education had mixed indirect influences via associations with life expectancy, the aging index, and relative income. Higher life expectancy had mixed relations with heat-related mortality, being associated with higher risk at moderate temperatures (0.33 ± 0.11 for the moderate slope; - 0.19 ± 0.097 for the MMTP) but lower underlying mortality rates (- 0.72 ± 0.097 ). A higher aging index was associated with higher burdens through higher risk at extreme temperatures (0.13 ± 0.072 for the extreme slope) and higher underlying mortality rates (0.93 ± 0.055 ). Relative income had relatively small, mixed influences.

DISCUSSION

Our novel approach provided insights into actions for reducing the health impacts of heat. First, the results show the interrelations between possible vulnerability-generating mechanisms and suggest future research directions. Second, the findings point to the need for a dual approach to adaptation, with actions that explicitly target heat exposure reduction and actions focused explicitly on the root causes of vulnerability. For the latter, the climate crisis may be leveraged to accelerate ongoing general public health programs. https://doi.org/10.1289/EHP11766.

Reimagining the Role of Health Departments and Their Partners in Addressing Climate Change: Revising the Building Resilience against Climate Effects (BRACE) Framework

Public health departments have important roles to play in addressing the local health impacts of climate change, yet are often not well prepared to do so. The Climate and Health Program (CHP) at the Centers for Disease Control and Prevention (CDC) created the Building Resilience Against Climate Effects (BRACE) framework in 2012 as a five-step planning framework to support public health departments and their partners to respond to the health impacts of climate change. CHP has initiated a process to revise the framework to address learnings from a decade of experience with BRACE and advances in the science and practice of addressing climate and health. The aim of this manuscript is to describe the methodology for revising the BRACE framework and the expected outputs of this process. Development of the revised framework and associated guidance and tools will be guided by a multi-sector expert panel, and finalization will be informed by usability testing. Planned revisions to BRACE will (1) be consistent with the vision of Public Health 3.0 and position health departments as "chief health strategists" in their communities, who are responsible for facilitating the establishment and maintenance of cross-sector collaborations with community organizations, other partners, and other government agencies to address local climate impacts and prevent further harm to historically underserved communities; (2) place health equity as a central, guiding tenet; (3) incorporate greenhouse gas mitigation strategies, in addition to its previous focus on climate adaptation; and (4) feature a new set of tools to support BRACE implementation among a diverse set of users. The revised BRACE framework and the associated tools will support public health departments and their partners as they strive to prevent and reduce the negative health impacts of climate change for everyone, while focusing on improving health equity.

The footprint of human-induced climate change on heat-related deaths in the summer of 2022 in Switzerland

Human-induced climate change is leading to an increase in the intensity and frequency of extreme weather events, which are severely affecting the health of the population. The exceptional heat during the summer of 2022 in Europe is an example, with record-breaking temperatures only below the infamous 2003 summer. High ambient temperatures are associated with many health outcomes, including premature mortality. However, there is limited quantitative evidence on the contribution of anthropogenic activities to the substantial heat-related mortality observed in recent times. Here we combined methods in climate epidemiology and attribution to quantify the heat-related mortality burden attributed to human-induced climate change in Switzerland during the summer of 2022. We first estimated heat-mortality association in each canton and age/sex population between 1990 and 2017 in a two-stage time-series analysis. We then calculated the mortality attributed to heat in the summer of 2022 using observed mortality, and compared it with the hypothetical heat-related burden that would have occurred in absence of human-induced climate change. This counterfactual scenario was derived by regressing the Swiss average temperature against global mean temperature in both observations and CMIP6 models. We estimate 623 deaths [95% empirical confidence interval (95% eCI): 151-1068] due to heat between June and August 2022, corresponding to 3.5% of all-cause mortality. More importantly, we find that 60% of this burden (370 deaths [95% eCI: 133-644]) could have been avoided in absence of human-induced climate change. Older women were affected the most, as well as populations in western and southern Switzerland and more urbanized areas. Our findings demonstrate that human-induced climate change was a relevant driver of the exceptional excess health burden observed in the 2022 summer in Switzerland.

Heat-mortality relationship in North Carolina: Comparison using different exposure methods

BACKGROUND

Many studies have explored the heat-mortality relationship; however, comparability of results is hindered by the studies' use of different exposure methods.

OBJECTIVE

This study evaluated different methods for estimating exposure to temperature using individual-level data and examined the impacts on the heat-mortality relationship.

METHODS

We calculated different temperature exposures for each individual death by using a modeled, gridded temperature dataset and a monitoring station dataset in North Carolina for 2000-2016. We considered individual-level vs. county-level averages and measured vs. modeled temperature data. A case-crossover analysis was conducted to examine the heat-mortality risk under different exposure methods.

RESULTS

The minimum mortality temperature (MMT) (i.e., the temperature with the lowest mortality rate) for the monitoring station dataset was 23.87 °C and 22.67 °C (individual monitor and county average, respectively), whereas for the modeled temperature dataset the MMT was 19.46 °C and 19.61 °C (individual and county, respectively). We found higher heat-mortality risk while using temperature exposure estimated from monitoring stations compared to risk based on exposure using the modeled temperature dataset. Individual-aggregated monitoring station temperature exposure resulted in higher heat mortality risk (odds ratio (95% CI): 2.24 (95% CI: 2.21, 2.27)) for a relative temperature change comparing the 99th and 90th temperature percentiles, while modeled temperature exposure resulted in lower odds ratio of 1.27 (95% CI: 1.25, 1.29).

SIGNIFICANCE

Our findings indicate that using different temperature exposure methods can result in different temperature-mortality risk. The impact of using various exposure methods should be considered in planning health policies related to high temperatures, including under climate change. IMPACT STATEMENT: (1) We estimated the heat-mortality association using different methods to estimate exposure to temperature. (2) The mean temperature value among different exposure methods were similar although lower for the modeled data, however, use of the monitoring station temperature dataset resulted in higher heat-mortality risk than the modeled temperature dataset. (3) Differences in mortality risk from heat by urbanicity varies depending on the method used to estimate temperature exposure.

The relationship between extreme ambient temperature and small for gestational age: A cohort study of 1,436,480 singleton term births in China

Studies have shown that exposure to extreme ambient temperature can contribute to adverse pregnancy outcomes, however, results across studies have been inconsistent. We aimed to evaluate the relationships between trimester-specific extreme temperature exposures and fetal growth restriction indicated by small for gestational age (SGA) in term pregnancies, and to assess whether and to what extent this relationship varies between different geographic regions. We linked 1,436,480 singleton term newborns (2014-2016) in Hubei Province, China, with a sub-district-level temperature exposures estimated by a generalized additive spatio-temporal model. Mixed-effects logistic regression models were employed to estimate the effects of extreme cold (temperature ≤5th percentile) and heat exposures (temperature >95th percentile) on term SGA in three different geographic regions, while adjusting for the effects of maternal age, infant sex, the frequency of health checks, parity, educational level, season of birth, area-level income, and PM_2.5 exposure. We also stratified our analyses by infant sex, maternal age, urban‒rural type, income categories and PM_2.5 exposure for robustness analyses. We found that both cold (OR:1.32, 95% CI: 1.25-1.39) and heat (OR:1.17, 95% CI: 1.13-1.22) exposures during the third trimester significantly increased the risk of SGA in the East region. Only extreme heat exposure (OR:1.29, 95% CI: 1.21-1.37) during the third trimester was significantly related to SGA in the Middle region. Our findings suggest that extreme ambient temperature exposure during pregnancy can lead to fetal growth restriction. Governments and public health institutions should pay more attention to environmental stresses during gestation, especially in the late stage of the pregnancy.

Temperature and socioeconomic vulnerability: associations with cardiac event-induced posttraumatic stress symptoms

Background

Posttraumatic stress symptoms (PTSS) are common after acute coronary syndrome (ACS) and predict increased morbidity and mortality. Climate change contributes to worse mental and cardiovascular health outcomes, thus, PTSS represent a potential mechanism linking climate change to adverse cardiovascular outcomes. Because people living in areas with lower socioeconomic status (SES) experience greater climate vulnerability, have worse cardiovascular health, and may be more susceptible to PTSS, any effect of temperature on PTSS could be amplified in this population.

Methods

Spatial regression models were estimated to test the association of temperature and temperature variability (within-day variability, directed change over time, and absolute change over time), census tract-level SES, and their interaction with PTSS 1 month post-hospital discharge in a longitudinal cohort study comprising 956 patients evaluated for ACS at an urban U.S. academic medical center between November 2013-May 2017. PTSS were self-reported in relation to the ACS event that brought the patient to the hospital. Census tract-level was computed as a composite score from the CDC Social Vulnerability Index, with higher values indicating lower SES.

Results

No temperature or temperature variability metrics were associated with PTSS. Lower census tract-level SES was associated with greater PTSS at 1 month. There was a marginally significant interaction of SES with ACS status, such that we only observed evidence of an association among those with ACS.

Conclusion

Temperature exposures were not associated with acute CVD-induced PTSS, which could be a result of a small sample size, mismatched timescale, or lack of a true effect. Conversely, lower census tract-level SES was associated with developing worse PTSS 1 month after evaluation for an ACS. This association appeared stronger in individuals with a true ACS. Early interventions to prevent PTSS could promote better mental and CVD outcomes in this at-risk population.

Exploring vulnerability to heat and cold across urban and rural populations in Switzerland

Heat- and cold-related mortality risks are highly variable across different geographies, suggesting a differential distribution of vulnerability factors between and within countries, which could partly be driven by urban-to-rural disparities. Identifying these drivers of risk is crucial to characterize local vulnerability and design tailored public health interventions to improve adaptation of populations to climate change. We aimed to assess how heat- and cold-mortality risks change across urban, peri-urban and rural areas in Switzerland and to identify and compare the factors associated with increased vulnerability within and between different area typologies. We estimated the heat- and cold-related mortality association using the case time-series design and distributed lag non-linear models over daily mean temperature and all-cause mortality series between 1990-2017 in each municipality in Switzerland. Then, through multivariate meta-regression, we derived pooled heat and cold-mortality associations by typology (i.e. urban/rural/peri-urban) and assessed potential vulnerability factors among a wealth of demographic, socioeconomic, topographic, climatic, land use and other environmental data. Urban clusters reported larger pooled heat-related mortality risk (at 99th percentile, vs. temperature of minimum mortality (MMT)) (relative risk=1.17(95%CI:1.10;1.24, vs peri-urban 1.03(1.00;1.06), and rural 1.03 (0.99;1.08)), but similar cold-mortality risk (at 1st percentile, vs. MMT) (1.35(1.28;1.43), vs rural 1.28(1.14;1.44) and peri-urban 1.39 (1.27-1.53)) clusters. We found different sets of vulnerability factors explaining the differential risk patterns across typologies. In urban clusters, mainly environmental factors (i.e. PM2.5) drove differences in heat-mortality association, while for peri-urban/rural clusters socio-economic variables were also important. For cold, socio-economic variables drove changes in vulnerability across all typologies, while environmental factors and ageing were other important drivers of larger vulnerability in peri-urban/rural clusters, with heterogeneity in the direction of the association. Our findings suggest that urban populations in Switzerland may be more vulnerable to heat, compared to rural locations, and different sets of vulnerability factors may drive these associations in each typology. Thus, future public health adaptation strategies should consider local and more tailored interventions rather than a one-size fits all approach. size fits all approach.

Association of Temperature Thresholds with Heat Illness- and Cardiorespiratory-Related Emergency Visits during Summer Months in Alaska

BACKGROUND

Recent record-breaking hot temperatures in Alaska have raised concerns about the potential human health implications of heat exposure among this unacclimated population.

OBJECTIVES

We estimated cardiorespiratory morbidity associated with days above summer (June-August) heat index (HI, apparent temperature) thresholds in three major population centers (Anchorage, Fairbanks, and the Matanuska-Susitna Valley) for the years 2015-2019.

METHODS

We implemented time-stratified case-crossover analyses of emergency department (ED) visits for International Classification of Diseases, 10^th Revision codes indicative of heat illness and major cardiorespiratory diagnostic codes using data from the Alaska Health Facilities Data Reporting Program. Using conditional logistic regression models, we tested maximum hourly HI temperature thresholds between 21.1°C (70°F) and 30°C (86°F) for a single day, 2 consecutive days, and the absolute number of previous consecutive days above the threshold, adjusting for the daily average concentration of particulate matter ≤2.5μg.

RESULTS

There were increased odds of ED visits for heat illness above a HI threshold as low as 21.1°C (70°F) [odds ratio (OR)=13.84; 95% confidence interval (CI): 4.05, 47.29], and this increased risk continued for up to 4 d (OR=2.43; 95% CI: 1.15, 5.10). Asthma and pneumonia were the only respiratory outcomes positively associated with the HI: ED visits for both were highest the day after a heat event (Asthma: HI>27°C(80°F) OR=1.18; 95% CI: 1.00, 1.39; Pneumonia: HI>28°C(82°F) OR=1.40; 95% CI: 1.06, 1.84). There was a decreased odds of bronchitis-related ED visits when the HI was above thresholds of 21.1-28°C (70-82°F) across all lag days. We found stronger effects for ischemia and myocardial infarction (MI) than for respiratory outcomes. Multiple days of warm weather were associated with an increased risk of health impacts. For each additional preceding day above a HI of 22°C (72°F), the odds of ED visits related to ischemia increased 6% (95% CI: 1%, 12%); for each additional preceding day above a HI of 21.1°C (70°F), the odds of ED visits related to MI increased 7% (95% CI: 1%, 14%).

DISCUSSION

This study demonstrates the importance of planning for extreme heat events and developing local guidance for heat warnings, even in areas with historically mild summertime climates. https://doi.org/10.1289/EHP11363.