Heat Deaths Research Articles

Health impacts of excessive heat in Multnomah County, OR, 2021

Abstract Human-induced climate change is leading to increased extreme weather events, such as the heat dome that occurred in Multnomah County, OR, in June 2021. Certain groups are at increased risk from excessive heat events, such as the very young and very old, persons without stable housing, and persons with certain health comorbidities. Our review of three data sources (deaths, hospitalizations, and emergency department visits) showed large increases in all three measures in the summer of 2021. Further, two-thirds of identified heat deaths occurred in or near neighborhoods that ranked among the most vulnerable to extreme heat. Despite thoughtful planning, a recently updated heat response plan, and an unprecedented mobilization of resources, we documented severe health impacts due to this heat event. We recommend that local health jurisdictions and emergency responders increase readiness for such events by interrogating existing plans and tailoring them not to events of expected severity, but to a worst case scenario that exceeds historic experiences.

A time-stratified, case-crossover study of heat exposure and perinatal mortality from 16 hospitals in sub-Saharan Africa.

Growing evidence suggests that extreme heat events affect both pregnant women and their infants, but few studies are available from sub-Saharan Africa. Using data from 138,015 singleton births in 16 hospitals in Benin, Malawi, Tanzania and Uganda, we investigated the association between extreme heat and early perinatal deaths, including antepartum and intrapartum stillbirths, and deaths within 24 h after birth using a time-stratified case-crossover design. We observed an association between an increase from the 75th to the 99th percentile in mean temperature 1 week (lag 0-6 d) before childbirth and perinatal mortality (odds ratio (OR) = 1.34 (95% confidence interval (CI) 1.01-1.78)). The estimates for stillbirths were similarly positive, but CIs included unity: OR = 1.29 (95% CI 0.95-1.77) for all stillbirths, OR = 1.18 (95% CI 0.71-1.95) for antepartum stillbirths and OR = 1.64 (95% CI 0.74-3.63) for intrapartum stillbirths. The cumulative exposure-response curve suggested that the steepest slopes for heat for intrapartum stillbirths and associations were stronger during the hottest seasons. We conclude that short-term heat exposure may increase mortality risks, particularly for intrapartum stillbirths, raising the importance of improved intrapartum care.

The burden of heat in arid regions of the Middle East: an analysis from Jordan and Kuwait

The Middle East, with its vast arid landscape, is facing escalating health risks due to intensifying heat under climate change. Kuwait and Jordan, two representative countries from the region, have no heat action plan in place. This study aims to (1) quantify the mortality burden of extreme heat in these countries, and hence (2) identify critical temperature thresholds. We collected 17 years of daily mortality records from 2000 to 2016 in Amman, Jordan, and the entire state of Kuwait. We fitted a time series design restricted to the summer months (June–August) for each location. We used distributed lag non-linear models to estimate non-linear associations and lagged effects of temperature on mortality. We then calculated attributable mortality for a range of temperature percentiles. We analyzed a total of 56 654 (39 996 all-cause deaths in Amman and 16 658 non-accidental deaths in Kuwait). Kuwait’s average summer temperature (38.7 °C) was higher than Amman (26.5 °C). In Kuwait, 202.1 (95% eCI: 17.7, 344.8) attributable heat deaths occurred over 79 d at temperatures above 41.9 °C (>95th percentile), averaging 2.6 heat deaths per day. Amman experienced 500.7 (95% eCI: 17.7, 344.8) attributable heat deaths over 77 d at temperatures above 30.75 °C, with an average of 6.5 deaths per day. This study equips Kuwait and Jordan with critical data to develop and implement targeted heat action plans. The two Middle Eastern countries face extreme heat challenges and are undergoing serious demographic changes with an influx of migrant workers and refugees. We provide an essential quantification of the mortality burden attributable to extreme heat in Kuwait and Jordan, two countries in the Middle East facing unprecedented heat and yet without existing heat action plans. Policymakers face the question of which thresholds represent negligible risk and which cannot be ignored. By analyzing 56 654 deaths, we reveal the number of deaths per day attributable to specific temperatures. This study presents the first step towards establishing targeted heat action plans to mitigate the health risks posed by intensifying heat. The methods used for Kuwait and Amman can be replicated in similar Middle Eastern countries.

Heat and Cardiovascular Mortality: An Epidemiological Perspective.

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

Integrating Shared Socioeconomic Pathway-informed adaptation into temperature-related mortality projections under climate change

The extent to which populations will successfully adapt to continued warming temperatures will be a crucial factor in determining future health burdens. Previous health impact assessments of future temperature-related mortality burdens mostly disregard adaptation or make simplistic assumptions. We apply a novel evidence-based approach to model adaptation that takes into account the fact that adaptation potential is likely to vary at different temperatures. Temporal changes in age-specific mortality risk associated with low and high temperatures were characterised for Scotland between 1974 and 2018 using temperature-specific RR ratios to reflect past changes in adaptive capacity. Three scenarios of future adaption were constructed consistent with the SSPs. These adaptation projections were combined with climate and population projections to estimate the mortality burdens attributable to high (above the 90th percentile of the historical temperature distribution) and low (below the 10th percentile) temperatures up to 2080 under five RCP-SSP scenarios. A decomposition analysis was conducted to attribute the change in the mortality burden into adaptation, climate and population. In 1980–2000, the heat burden (21 deaths/year) was smaller than the colder burden (312 deaths/year). In the 2060–2080 period, the heat burden was projected to be the highest under RCP8.5-SSP5 (1285 deaths/year), and the cold burden was the highest under RCP4.5-SSP4 (320 deaths/year). The net burden was lowest under RCP2.6-SSP1 and highest under RCP8.5-SSP5. Improvements in adaptation was the largest factor reducing the cold burden under RCP2.6-SSP1 whilst temperature increase was the biggest factor contributing to the high heat burdens under RCP8.5-SSP5. Ambient heat will become a more important health determinant than cold in Scotland under all climate change and socio-economic scenarios. Adaptive capacity will not fully counter projected increases in heat deaths, underscoring the need for more ambitious climate mitigation measures for Scotland and elsewhere.

Feeling the heat? Analyzing climate change sentiment in Spain using Twitter data

To shed light on the recent debate about climate change in this post-pandemic scenario, we take advantage of a unique dataset that combines geo-tagged social media data from Twitter in Spain from 2017 to 2022. Twitter conversations have been analyzed with natural language processing techniques to obtain sentiment scores related to climate change. These were merged with additional relevant control variables, aiming to understand the role of the contributing factors on the evolution of the hedonic scores, including external temperatures, the occurrence of heat waves, and deaths related to climate. We find a strong negative effect of external temperatures on sentiment, aggravated by recent increases in the frequency of heat waves and deaths related to climate. Further, this negative sentiment is accentuated after experiencing the recent COVID-19.

Premature Deaths Due To Heat Exposure: The Potential Effects of Neighborhood-Level Versus City-Level Acclimatization Within US Cities.

For the population of a given US city, the risk of premature death associated with heat exposure increases as temperatures rise, but risks in hotter cities are generally lower than in cooler cities at equivalent temperatures due to factors such as acclimatization. Those living in especially hot neighborhoods within cities might therefore suffer much more than average if such adaptation is only at the city-wide level, whereas they might not experience greatly increased risk if adjustment is at the neighborhood level. To compare these possibilities, we use high spatial resolution temperature data to evaluated heat-related deaths assuming either adjustment at the city-wide or at the neighborhood scale in 10 large US cities. On average, we find that if inhabitants are adjusted to their local conditions, a neighborhood that was 10°C hotter than a cooler one would experience only about 1.0-1.5 excess heat deaths per year per 100,000 persons. By contrast, if inhabitants are acclimatized to city-wide temperatures, the hotter neighborhood would experience about 15 excess deaths per year per 100,000 persons. Using idealized analyses, we demonstrate that current city-wide epidemiological data do not differentiate between these differing adjustments. Given the very large effects of assumptions about neighborhood-level acclimatization found here, as well as the fact that current literature is conflicting on the spatial scale of acclimatization, more neighborhood-level epidemiological data are urgently needed to determine the health impacts of variations in heat exposure within urban areas, better constrain projected changes, and inform mitigation efforts.

Suddenly, Last Summer: Heat Deaths of Athletes, Soldiers, and Hikers.

Suddenly, Last Summer: Heat Deaths of Athletes, Soldiers, and Hikers.

Schizophrenia pinpointed as a key factor in heat deaths

The mental illness tripled the risk of death during a searing 2021 heat wave, researchers find.

Improving attribution of extreme heat deaths through interagency cooperation

Attributing individual deaths to extreme heat events (EHE) in Canada and elsewhere is important for understanding the risk factors, protective interventions, and burden of mortality associated with climate change. However, there is currently no single mechanism for identifying individual deaths due to EHE and different agencies have taken different approaches, including (1) vital statistics coding based on medical certificates of death, (2) probabilistic methods, and (3) enhanced surveillance. The 2018 EHE in Montréal provides an excellent case study to compare EHE deaths identified by these different approaches. There were 353 deaths recorded in the vital statistics data over an 8-day period, of which 102 were potentially attributed to the EHE by at least one approach and 251 were not attributed by any approach. Only nine of the 102 deaths were attributed to the EHE by all three approaches, 23 were attributed by two approaches, and 70 were attributed by only one approach. Given that there were approximately 50 excess deaths during the EHE, it remains unclear exactly which of the total 353 deaths should be attributed to the extreme temperatures. These results highlight the need for a more systematic and cooperative approach to EHE mortality in Canada, which will continue to increase as the climate changes.

Projecting the impacts of housing on temperature-related mortality in London during typical future years

Climate change means the UK will experience warmer winters and hotter summers in the future. Concurrent energy efficiency improvements to housing may modify indoor exposures to heat or cold, while population aging may increase susceptibility to temperature-related mortality. We estimate heat and cold mortality and energy consumption in London for typical (non-extreme) future climates, given projected changes in population and housing. Building physics models are used to simulate summertime and wintertime indoor temperatures and space heating energy consumption of London dwellings for ‘baseline’ (2005–2014) and future (2030s, 2050s) periods using data from the English Housing Survey, historical weather data, and projected future weather data with temperatures representative of ‘typical’ years. Linking to population projections, we calculate future heat and cold attributable mortality and energy consumption with demolition, construction, and alternative scenarios of energy efficiency retrofit. At current retrofit rates, around 168–174 annual cold-related deaths per million population would typically be avoided by the 2050s, or 261–269 deaths per million under ambitious retrofit rates. Annual heat deaths would typically increase by 1 per million per year under the current retrofit rate, and 12–13 per million under ambitious rates without population adaptation to heat. During typical future summers, an estimated 38–73% of heat-related deaths can be avoided using external shutters on windows, with their effectiveness lower during hotter weather. Despite warmer winters, ambitious retrofit rates are necessary to reduce typical annual energy consumption for heating below baseline levels, assuming no improvement in heating system efficiencies. Concerns over future overheating in energy efficient housing are valid but increases in heat attributable mortality during typical and hot (but not extreme) summers are more than offset by significant reductions in cold mortality and easily mitigated using passive measures. More ambitious retrofit rates are critical to reduce energy consumption and offer co-benefits for reducing cold-related mortality.

More than one-third of heat deaths blamed on climate change

More than one-third of heat deaths blamed on climate change

Exertional heat fatalities in Australian sport and recreation

ObjectivesTo describe the number and case characteristics of sport and recreation-related exertional heat deaths in Australia and summarise recommendations derived from case narratives. DesignDescriptive, population-based, retrospective cohort study. MethodsCases were identified using the National Coronial Information System (NCIS) through multiple search strategies comprising queries, keywords and cause of death codes. Cases were included where there was evidence that the deceased was actively engaged in sport or recreation and exertional heat illness was causal or contributory to the death. Data extraction were performed independently, in duplicate, to ensure accuracy. Descriptive statistics are used to report deceased's socio-demographic characteristics, incident characteristics, type of sport/recreational activity and time sequence of events. Content analysis is used to summarise recommendations. ResultsThirty-eight deaths (males n = 29, 74%; median age = 40 years, range 8–77) were identified during the study period (2001 to 2018), with 22 recommendations for five cases. Two cases occurred during organised sport and 36 during active recreation, of which 27 were in hiking. Eleven (29%) individuals were international visitors. There were 22 recommendations across 5 cases presented, with a focus on education and training. ConclusionsExertional heat deaths in outdoor recreation in Australia were far more prevalent than cases in organised sport. The largest proportion of deaths occurred in hiking with two populations featuring: males aged 15–45 years and international visitors. Considering the incident characteristics and time sequence of events, measures such as early recognition of symptoms, provision of first aid and timely access to emergency medical care are important to prevent fatalities.

Mortality benefit of building adaptations to protect care home residents against heat risks in the context of uncertainty over loss of life expectancy from heat

We explore methodological issues core to the cost-benefit evaluation of building adaptations designed to protect against heat risks to residents of care homes in England in the context of the uncertainties relating to the loss of life expectancy in heat death. We used building physics modelling to quantify the impact of external window shading on indoor temperatures. We calculated associated heat mortality and loss of life expectancy under three sets of assumptions of life-shortening based on: (Method 1) an England & Wales (E&W) life-table, (Method 2) E&W life-table scaled to match observed average survival of care home residents and (Method 3) assuming that those dying of heat have a life expectancy of six months. External window shading was estimated to reduce mean indoor temperatures by 0.9 °C in a ‘warm’ summer and 0.6 °C in an ‘average’ summer. In a care home of 50 residents, the heat deaths and years of life lost (YLL) averted by such shading were estimated by the three life-expectancy assumptions (Methods 1, 2, 3) to be: 0.07, 0.47 and 0.28 heat deaths and 0.29, 0.76 and 0.14 YLL for the warm year and 0.05, 0.31 and 0.19 heat deaths and 0.20, 0.51 and 0.10 YLL for the average year. Over a 20-year time horizon and assuming an annual discount rate of 3.5%, the monetized benefit of reduced YLL would be around £90,000, £230,000 and £44,000 with the three life-expectancy assumptions. Although this range represents appreciable uncertainty, it appears that modest cost adaptations to heat risk may be justified in conventional cost-benefit terms even under conservative assumptions about life expectancy.

Empirically Derived Equation from Simple Heat Index for Calculating Wet Bulb Globe Temperature: A Case Study of Thailand

The Wet Bulb Globe Temperature (WBGT) index is a standard for assessing environmental heat stress, but the requirement of expensive instrument with specialized maintenance is limited its use. This study aims to develop the empirical equation to estimate the WBGT from Heat Index (HI) calculated from portable temperature and humidity recorder (THR), based on the data collected at seven sites covering all regions of Thailand. Comparative analysis shows that the HI values calculated from THR (HITHR) are consistent well with those measured from the thermal environmental monitor (HIQT36) as evidenced by a highly positive correlation between them (r=0.97; p<0.01; n=4,303). These results suggest high reliability of the portable THR and its acceptance to be used instead of the standard QT36 device. Based on a simple linear regression developed to estimate WBGT from the HITHR, it was found that the model accounts for at least 90% of the variance of the observed WBGT (dependent variable). In addition, validation of the model with the statistical methods shows relatively small errors of the estimated WBGT values in comparison to the observed values. With this evidence, the developed empirical regression equation can be used to estimate WBGT with high accuracy and confidence. Simple and easier to use for the practitioners who are involved in public health works at community level, a heat monitoring tool kit consisting of a THR, WBGT chart and recommended actions were further developed based on the results obtained. This tool kit is a low-cost and simple device which can be used by various community-level stakeholders to prevent and reduce heat injuries and deaths of risk groups, especially the elderly. This tool is necessary in light of anthropogenic-induced warming and Thailand’s aging society.

Structure of urban green space and its associations with heat and air pollution related deaths

Structure of urban green space and its associations with heat and air pollution related deaths

Health Risks and Interventions in Exertional Heat Stress.

With climate change, heat waves are expected to become more frequent in the near future. Already, on average more than 25 000 "heat deaths" are estimated to occur in Europe every year. However, heat stress and heat illnesses arise not just when ambient temperatures are high. Physical exertion increases heat production within the organism many times over; if not enough heat is lost, there is a risk of exertional heat stress. This review article discusses contributing factors, at-risk groups, and the diagnosis and treatment of heat illnesses. A selective literature search was carried out on PubMed. Current guidelines and expert recommendations were also included. Apart from muscular heat production (>70% of converted energy), there are other factors that singly or in combination can give rise to heat stress: clothing, climate/acclimatization, and individual factors. Through its insulating properties, clothing reduces the evaporation of sweat (the most effective physiological cooling mechanism). A sudden heat wave, or changing the climate zone (as with air travel), increases the risk of a heat-related health event. Overweight, low fitness level, acute infections, illness, dehydration, and other factors also reduce heat tolerance. In addition to children, older people are particularly at risk because of their reduced physiological adaptability, (multi-)morbidity, and intake of prescription drugs. A heat illness can progress suddenly to life-threatening heat stroke. Successful treatment depends on rapid diagnosis and cooling the body down as quickly as possible. The aim is to reduce core body temperature to <40 °C within 30 minutes. Immediately effective cooling interventions are the only causal treatment for heat stroke. Time once lost cannot be made up. Prevention (acclimatization, reduced exposure, etc.) and terminating the heat stress in good time (e.g., stopping work) are better than any cure.

Weekly heat wave death prediction model using zero-inflated regression approach

Driven partly by the shifting climate and growth of vulnerable populations, excess heat-triggered human fatalities are becoming a serious public health risk concern in Korea. This study develops the zero-inflated regression model for predicting the numbers of weekly heat deaths in South Korea. Defining the heat death as the death caused by “exposure to excessive natural heat,” data analyses are performed to examine statistical relationships between the number of heat deaths versus the pertinent temperature-related parameters and the size of the vulnerable population. The weekly mean of daily maximum temperature and the number of consecutive heat wave days with tropical nights are selected as the temperature-related parameters, while the numbers of elderly living alone and those of agricultural workers are selected as the parameters representing the vulnerable population. Using these four regressive parameters, we develop a regression-based model applied for the prediction of the number of heat deaths. Several statistical methods including the Poisson, negative binomial, hurdle, and the zero-inflated models are scrutinized. The results demonstrate that the zero-inflated Poisson regression model is the most appropriate statistical approach, as it addresses the issue of frequent occurrences of zero-valued observations in weekly heat death data. It was evident that a larger number of heat deaths occurred in the period and study region with a correspondingly higher predicted value. In accordance with this statistical performance, we ascertain that the utilized models could be explored by disaster management and public health experts as a scientific contrivance for health risk mitigation and resource allocation more strategically, and for providing the general public with reliable weekly heat wave risk forecasts.

Without Warning: Worker Deaths From Heat 2014-2016.

Worker deaths from heat exposure are unlike heat deaths in the general population; workers tend to be outside in variable temperatures and younger than sixty-five years. Climate change will increase the frequency, duration, and variability of hot temperatures. Public health warning systems, such as the Heat Index of the National Weather Service, do not generally account for workers' greater likelihood of exposure to direct sunlight or exertion. Only 28% of the 79 worker heat-related fatalities during 2014-2016 occurred on days when the National Weather Service warning would have included the possibility of fatal heat stroke. Common heat illness prevention advice ignores workers' lack of control over their ability to rest and seek cooler temperatures. Additionally, acclimatization, or phased-in work in the heat, may be less useful given temperature variability under climate change. Workers' vulnerability and context of heat exposure should inform public health surveillance and response to prevent heat illness and death.

Are Non-US Citizens More Likely to Die From Heat Exposure?

The article responds to an issue article on heat-related mortality among U.S. citizens as compared with among U.S. non-citizen residents. Topics include problems with heat intervention measures among at-risk non-citizens, regional prevalence of heat deaths in the Southwestern U.S., and the need for more accurate reporting of heat-related deaths.