Analysis of community deaths during the catastrophic 2021 heat dome: Early evidence to inform the public health response during subsequent events in greater Vancouver, Canada

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.

Effect of Electric Fans on Body Core Temperature in Older Adults Exposed to Extreme Indoor Heat

This study assessed whether electric fans limit core temperature increases in adults aged 65 to 85 years exposed to conditions similar to those experienced in homes during heat waves in North America.

Heat-related illness among workers in British Columbia, Canada: Extreme hot weather in 2021 compared to 2001-2020

OBJECTIVES

British Columbia (BC), Canada, experienced an unprecedented summer with record-breaking high temperatures in 2021. Yet the health impact has not been examined in occupational settings. This study aimed to characterize occupational heat-related illness (HRI) among BC workers estimated by incidence rates and associations between heatwaves and HRI, compare risks from 2021 and prior summers of 2001-2020, and assess differential impacts on worker groups by demographics and occupations.

METHODS

We identified HRI from workers' compensation claims that occurred between June and August from 2001-2021 in BC. Incidence rates were calculated using working population estimates from Statistics Canada's Labour Force Survey. A time-stratified case-crossover design with conditional Poisson regression was used to examine the impact of heatwaves on occupational HRI. All analyses were stratified by year (2021 versus 2001-2020), age, sex, and occupation.

RESULTS

Of the 521 claims identified, 107 (21%) occurred in 2021. Incidence rates for 2021 and prior summers were 3.97 [95% confidence interval (CI) 3.26-4.80] and 0.93 (95% CI 0.85-1.03) claims per 100 000 workers, respectively. This difference represents a 327% increase. Rates were higher in health occupations in 2021 versus 2001-2020. During 2001-2021, the risk of HRI during heatwave days was 4.33 (95% CI 2.98-6.27) times that during non-heatwave days, and the risk was higher among middle-aged workers and workers in trades, transport, and equipment operations. The 2021 heatwaves had greater impact on younger and female workers than those from prior summers.

CONCLUSIONS

Heat is a crucial workplace hazard. Prevention strategies should prioritize at-risk workers and not be limited to heatwaves.

Media-Based Post-Event Impact Analysis of the 2021 Heat Dome in Canada

The unprecedented 2021 Heat Dome caused wide-ranging and long-lasting impacts in western Canada, including 619 confirmed heat-related deaths in British Columbia, a doubling of emergency medical calls, increased hospitalisations, infrastructure failures and stress on plants and animals. However, such varied socio-economic consequences of extreme heat can be challenging to capture using a single post-event analysis method. Therefore, there is a need to explore alternative approaches and data sources. Using the 2021 Heat Dome as a case study, a post-event analysis using online news media articles (n = 2909) from 5 subscription news databases and a grey literature search was conducted to identify the socio-economic impacts of the extreme heat event in Canada. The articles reported a wide range of effects to the natural environment (n = 1366), social infrastructure and services (n = 1121), human health (n = 1074), critical infrastructure (n = 988) and the private sector (n = 165). The media-based post-event analysis captured various impacts, some of which have not been identified through other data sources and approaches. Overall, we show that media analysis can complement traditional post-event analysis methods and provide additional perspectives to governments and public health and safety officials.

Markers of enterocyte damage, microbial translocation, and systemic inflammation following 9 h of heat exposure in young and older adults

Heat stress induced damage to the gastrointestinal barrier can induce local and systemic inflammatory reactions implicated in heat-stroke. Gastrointestinal barrier damage has been shown to be greater in older relative to young adults following hyperthermia. However, comparisons between young and older adults have been limited to brief exposures (3 h), which may not reflect the duration of heat stress experienced during heat waves. We therefore evaluated markers of intestinal epithelial damage (log transformed intestinal fatty acid binding protein, IFABPLOG), microbial translocation (soluble cluster of differentiation 14, sCD14LOG), and systemic inflammation (tumour necrosis factor alpha, TNF-αLOG; interleukin 6, IL-6LOG; C-reactive protein, CRP) in 19 young (interquartile range: 21-27 years; 10 females) and 37 older (68-73 years; 10 females) adults before and after 9 h of rest in 40 °C (9% relative humidity). The magnitude of the increase in IFABPLOG was 0.38 log pg/mL (95% CI, 0.10, 0.65 log pg/mL) greater in the older relative to young cohort (P = 0.049) after 9 h heat exposure. At baseline both IL-6LOG and CRP concentrations were higher in the older (IL-6: 2.67 (1.5) log pg/mL, CRP: 0.28 (1.5) mg/mL) relative to the young (IL-6: 1.59 log pg/mL, SD 1.2; CRP: 0.11 mg/mL, SD 1.7) group (both P ≤ 0.001). The change in IL-6 and CRP was similar between groups following 9 h heat exposure (IL-6: P = 0.053; CRP: P = 0.241). Neither sCD14LOG and TNF-αLOG were different between groups at baseline nor altered after 9 h heat exposure. Our data indicate that age may modify intestinal epithelial injury following 9 h of passive heat exposure.

Time to reach equilibrium deep body temperatures in young and older adults resting in the heat: a descriptive secondary analysis

It is commonly thought that steady-state thermoregulatory responses are achieved within 30-90 min of compensable heat stress. However, this assumption is based on measurements of whole body heat exchange during exercise, which stabilize (equilibrate) more rapidly than deep body temperatures, especially under resting conditions. To support the design of ecologically relevant heat exposure studies, we quantified equilibrium times for deep body temperature, as indexed by rectal temperature, in young and older adults resting in the heat. We also evaluated the lag in rectal temperature equilibrium relative to whole body heat storage (direct calorimetry). Equilibrium times were estimated with data from two laboratory-based trials (NCT04353076 and NCT04348630) in which 83 adults aged 19-80 yr (34 female) were exposed to simulated heat-wave conditions for 8-9 h. When assessed at the group level, it took rectal temperature 3.3 [bootstrap 95% confidence interval: 2.9-3.9] h to reach thermal equilibrium (<0.05°C/h rate of change) in young adults exposed to 40°C, 9% relative humidity (RH). In older adults, who were exposed to a greater range of conditions (31°C-40°C, 9-45% RH), equilibrium times were longer, ranging from 4.4 [3.8-5.3] to 5.2 [4.9-5.4] h. Furthermore, rectal temperature equilibrium was delayed 0.9 [0.5-1.4] and 1.8 [0.9-2.7] h compared with whole body heat storage in young and older adults, respectively (only assessed in 40°C, 9% RH). Individual-level equilibrium times ranged from 1 to 8 h. These findings highlight the importance of ecologically relevant exposure durations in translational research assessing the physiological impacts of hot weather.NEW & NOTEWORTHY Deep body (rectal) temperature took 3-5 h on average and up to 6-8 h at the individual level to reach thermal equilibrium in young and older adults resting in the heat. Furthermore, stable rectal temperatures were delayed by up to 2 h relative to the achievement of heat balance (0 kJ/min rate of heat storage). We provide the first quantification of the temporal profiles of thermal strain during extended rest in conditions simulating hot weather.

Exploring the contribution of inter-individual factors to the development of physiological heat strain in older adults exposed to simulated indoor overheating

Older adults are at elevated risk of heat-related mortality due to age-associated declines in thermoregulatory and cardiovascular function. However, the inter-individual factors that exacerbate physiological heat strain during heat exposure remain unclear, making it challenging to identify more heat-vulnerable subgroups. We therefore explored factors contributing to inter-individual variability in physiological responses of older adults exposed to simulated hot weather. Thirty-seven older adults (61-80 years, 16 females) rested for 8 h in 31 and 36 °C (45% relative humidity). Core (rectal) temperature, heart rate (HR), HR variability, mean arterial pressure (MAP), and cardiac autonomic responses to standing were measured at baseline and end-exposure. Bootstrapped least absolute shrinkage and selection operator regression was used to evaluate whether variation in these responses was related to type 2 diabetes (T2D, n = 10), hypertension (n = 18), age, sex, body morphology, habitual physical activity levels, and/or heat-acclimatization. T2D was identified as a predictor of end-exposure HR (with vs. without: 13 beats/min (bootstrap 95% confidence interval: 6, 23)), seated MAP (-7 mmHg (-18, 1)), and the systolic pressure response to standing (20 mmHg (4, 36)). HR was also influenced by sex (female vs. male: 8 beats/min (1, 16)). No other predictors were identified. The inter-individual factors explored did not meaningfully contribute to the variation in body temperature responses in older adults exposed to simulated indoor overheating. By contrast, cardiovascular responses were exacerbated in females and individuals with T2D. These findings improve understanding of how inter-individual differences contribute to heat-induced physiological strain in older persons.

NPCC4: Climate change and New York City's health risk

This chapter of the New York City Panel on Climate Change 4 (NPCC4) report considers climate health risks, vulnerabilities, and resilience strategies in New York City's unique urban context. It updates evidence since the last health assessment in 2015 as part of NPCC2 and addresses climate health risks and vulnerabilities that have emerged as especially salient to NYC since 2015. Climate health risks from heat and flooding are emphasized. In addition, other climate-sensitive exposures harmful to human health are considered, including outdoor and indoor air pollution, including aeroallergens; insect vectors of human illness; waterborne infectious and chemical contaminants; and compounding of climate health risks with other public health emergencies, such as the COVID-19 pandemic. Evidence-informed strategies for reducing future climate risks to health are considered.

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.

Responding to the Heat and Planning for the Future: An Interview-Based Inquiry of People with Schizophrenia Who Experienced the 2021 Heat Dome in Canada

People with schizophrenia have died at disproportionately higher rates during recent extreme heat events (EHEs) in Canada, including the deadly 2021 Heat Dome in British Columbia (B.C.). However, to date, little research has qualitatively focused on how people with schizophrenia experience and respond to EHEs. This study aimed to (i) explore how people with schizophrenia experienced and were impacted by the 2021 Heat Dome physically, cognitively, and emotionally and (ii) understand their level of awareness and health-protective actions taken in response to the EHE. Between October 2023 and February 2024, interviews were conducted with 35 people with schizophrenia who experienced the 2021 Heat Dome in a community setting within B.C., Canada. The semi-structured interviews were guided by pre-defined questions to explore the participant's background, living situation, social network, awareness and access to heat-mitigation measures. The transcripts were analyzed using a descriptive form of thematic analysis. Participants shared critical insights on how the EHE impacted them, including descriptions of mild to severe physical manifestations of heat stress (e.g., fainting, heat rashes), the triggering of schizophrenia-related symptoms (e.g., paranoia, hallucinations), and the detrimental effects on their energy levels and emotional stability, which further caused disruptions to their everyday life. Participants also illustrated gaps in knowledge and challenges experienced with accessing information, which hindered their ability to manage the heat exposure effectively and, for some, resulted in no actions (or counter-intuitive actions) being taken to mitigate the heat. These findings demonstrate the complex ways that individuals with schizophrenia experienced and responded to the 2021 Heat Dome and revealed various situational and contextual factors that further compounded the challenge of heat mitigation. These findings can support the development of tailored individual and community-level heat response and communication initiatives and strategies for people with schizophrenia.

The effect of foot immersion and neck cooling on cardiac autonomic function in older adults exposed to indoor overheating: a randomized crossover trial

Foot immersion and neck cooling are recommended cooling strategies for protecting heat-vulnerable persons during heat waves. While we recently showed that these strategies do not limit core temperature increases in older adults during prolonged heat exposure, we did observe small reductions in heart rate. Expanding on these findings, we examined the effects of foot immersion with and without neck cooling on cardiac autonomic function. Seventeen adults (9 females; 65-81 years) underwent 3 randomized, 6 h exposures to 38 °C and 35% relative humidity with: no cooling (control), foot immersion (20 °C water), or foot immersion with a wet towel (20 °C) around the neck. Cardiac autonomic responses were measured at baseline and end-exposure. These included heart rate variability, cardiac and systolic blood pressure responses to standing, indexed via the 30:15 ratio and supine-to-standing systolic pressure change, respectively, and baroreflex sensitivity during repeated sit-to-stand maneuvers. The 30:15 ratio was 0.04 [95% CI: 0.01, 0.07] greater with foot immersion and neck cooling (1.08 (SD: 0.04)) relative to control (1.04 (0.06); P = 0.018). Similarly, standing systolic blood pressure was elevated 9 [0, 17] mmHg with foot immersion and neck cooling (P = 0.043). That said, neither difference remained statistically significant after adjusting for multiplicity (Padjusted ≥ 0.054). No differences in 30:15 ratio or standing systolic blood pressure were observed with foot immersion alone, while heart rate variability and baroreflex sensitivity were unaffected by either cooling intervention. While foot immersion with neck cooling potentially improved cardiac autonomic responses in older adults exposed to simulated indoor overheating, these effects were small and of questionable clinical importance.

Spatial datasets of 30-year (1991-2020) average monthly total precipitation and minimum/maximum temperature for Canada and the United States

Thin plate smoothing spline models, covering Canada and the continental United States, were developed using ANUSPLIN for 30-year (1991-2020) monthly mean maximum and minimum temperature and precipitation. These models employed monthly weather station values from the North American dataset published by National Oceanic and Atmospheric Administration's (NOAA's) National Centers for Environmental Information (NCEI). Maximum temperature mean absolute errors (MAEs) ranged between 0.54 °C and 0.64 °C (approaching measurement error), while minimum temperature MAEs were slightly higher, varying from 0.87 °C to 1.0 °C. On average, thirty-year precipitation estimates were accurate to within approximately 10 % of total precipitation levels, ranging from 9.0 % in the summer to 12.2 % in the winter. Error rates were higher in Canada compared to estimates in the United States, consistent with a less dense station network in Canada relative to the United States. Precipitation estimates in Canada exhibited MAEs representing 14.7 % of mean total precipitation compared to 9.7 % in the United States. The datasets exhibited minimal bias overall; 0.004 °C for maximum temperature, 0.01 °C for minimum temperature, and 0.5 % for precipitation. Winter months showed a greater dry bias (0.8 % of total winter precipitation) compared to other seasons (-0.4 % of precipitation). These 30-year gridded datasets are available at ∼2 km resolution.

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

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

HealthyPlan.City: A Web Tool to Support Urban Environmental Equity and Public Health in Canadian Communities

Urban environmental factors such as air quality, heat islands, and access to greenspaces and community amenities impact public health. Some vulnerable populations such as low-income groups, children, older adults, new immigrants, and visible minorities live in areas with fewer beneficial conditions, and therefore, face greater health risks. Planning and advocating for equitable healthy urban environments requires systematic analysis of reliable spatial data to identify where vulnerable populations intersect with positive or negative urban/environmental characteristics. To facilitate this effort in Canada, we developed HealthyPlan.City ( https://healthyplan.city/ ), a freely available web mapping platform for users to visualize the spatial patterns of built environment indicators, vulnerable populations, and environmental inequity within over 125 Canadian cities. This tool helps users identify areas within Canadian cities where relatively higher proportions of vulnerable populations experience lower than average levels of beneficial environmental conditions, which we refer to as Equity priority areas. Using nationally standardized environmental data from satellite imagery and other large geospatial databases and demographic data from the Canadian Census, HealthyPlan.City provides a block-by-block snapshot of environmental inequities in Canadian cities. The tool aims to support urban planners, public health professionals, policy makers, and community organizers to identify neighborhoods where targeted investments and improvements to the local environment would simultaneously help communities address environmental inequities, promote public health, and adapt to climate change. In this paper, we report on the key considerations that informed our approach to developing this tool and describe the current web-based application.

Heatwave attribution based on reliable operational weather forecasts

The 2021 Pacific Northwest heatwave was so extreme as to challenge conventional statistical and climate-model-based approaches to extreme weather attribution. However, state-of-the-art operational weather prediction systems are demonstrably able to simulate the detailed physics of the heatwave. Here, we leverage these systems to show that human influence on the climate made this event at least 8 [2-50] times more likely. At the current rate of global warming, the likelihood of such an event is doubling every 20 [10-50] years. Given the multi-decade lower-bound return-time implied by the length of the historical record, this rate of change in likelihood is highly relevant for decision makers. Further, forecast-based attribution can synthesise the conditional event-specific storyline and unconditional event-class probabilistic approaches to attribution. If developed as a routine service in forecasting centres, it could provide reliable estimates of human influence on extreme weather risk, which is critical to supporting effective adaptation planning.

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.

A critical review of the effectiveness of electric fans as a personal cooling intervention in hot weather and heatwaves

Health agencies worldwide have historically cautioned that electric fans accelerate body-heat gain during hot weather and heatwaves (typically in air temperatures ≥35°C). However, guidance published since 2021 has suggested that fans can still cool the body in air temperatures up to 40°C by facilitating sweat evaporation, and therefore are an inexpensive yet sustainable alternative to air conditioning. In a critical analysis of the reports cited to support this claim, we found that although fan use improves sweat evaporation, these benefits are of insufficient magnitude to exert meaningful reductions in body core temperature in air temperatures exceeding 35°C. Health agencies should continue to advise against fan use in air temperatures higher than 35°C, especially for people with compromised sweating capacity (eg, adults aged 65 years or older). Improving access to ambient cooling strategies (eg, air conditioning or evaporative coolers) and minimising their economic and environmental costs through policy initiatives, efficient cooling technology, and combined use of low-cost personal interventions (eg, skin wetting or fan use) are crucial for climate adaptation.

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

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

The association of extreme environmental heat with incidence and outcomes of out-of-hospital cardiac arrest in British Columbia: A time series analysis

Background

The impact of extreme heat on out-of-hospital cardiac arrest (OHCA) incidence and outcomes is under-studied. We investigated OHCA incidence and outcomes over increasing temperatures.

Methods

We included non-traumatic EMS (Emergency Medical Services)-assessed OHCAs in British Columbia during the warm seasons of 2020-2021. We fit a time-series quasi-Poisson generalized linear model to estimate the association between temperature and incidence of both EMS-assessed, EMS-treated, and EMS-untreated OHCAs. Second, we employed a logistic regression model to estimate the association between "heatwave" periods (defined as a daily mean temperature > 99th percentile for ≥ 2 consecutive days, plus 3 lag days) with survival and favourable neurological outcomes (cerebral performance category ≤ 2) at hospital discharge.

Results

Of 5478 EMS-assessed OHCAs, 2833 were EMS-treated. OHCA incidence increased with increasing temperatures, especially exceeding a daily mean temperature of 25 °C Compared to the median daily mean temperature (16.9 °C), the risk of EMS-assessed (relative risk [RR] 3.7; 95%CI 3.0-4.6), EMS-treated (RR 2.9; 95%CI 2.2-3.9), and EMS-untreated (RR 4.3; 95%CI 3.2-5.7) OHCA incidence were higher during days with a temperature over the 99th percentile. Of EMS-treated OHCAs, during the heatwave (n = 179) and non-heatwave (n = 2654) periods, 4 (2.2%) and 270 (10%) survived and 4 (2.2%) and 241 (9.2%) had favourable neurological outcomes, respectively. Heatwave period OHCAs had decreased odds of survival (adjusted OR 0.28; 95%CI 0.10-0.79) and favourable neurological outcome (adjusted OR 0.31; 95%CI 0.11-0.89) at hospital discharge, compared to other periods.

Conclusion

Extreme heat was associated with a higher incidence of OHCA, and lower odds of survival and favourable neurological status at hospital discharge.

Temperature projections and heatwave attribution scenarios over India: A systematic review

The average global temperature is rising due to anthropogenic emissions. Hence, a systematic approach was used to examine the projected impacts of rising global temperatures on heatwaves in India and provide insights into mitigation and adaptation strategies. With over 24,000 deaths attributed to heatwaves from 1992 to 2015, there is an urgent need to understand India's vulnerabilities and prepare adaptive strategies under various emission scenarios.This situation is predicted to worsen as heatwaves become more frequent, intense, and long-lasting. Severe heatwaves can exacerbate chronic health conditions, vector-borne diseases, air pollution, droughts and other socio-economic pressures causing higher mortality and morbidity. Heatwaves with severe consequences have increased and are expected to become more frequent in Indian climatic and geographical conditions. As per the future projection studies, the temperature could rise ±1.2° C to ±3.5° C and will start reducing by the end of 2050. The study also provides data from the research that employs climatic models and statistical approaches for a more precise characterization of heat extremes and improved projections. Also, the study appraises the past, present and future heatwave trend projections. Most of these studies compute future projections using the Coupled Model Intercomparison Project (CMIP5) models and Representative Concentration Pathway (RCP). Limited systematic reports have been found using CMIP6, whereas the best-suited and widely used method was the RCP8.5. The study findings will aid in identifying the zones most susceptible to heatwave risk and provide actionable projections for policymakers to examine the existing evidence for developing proper planning and policy formulation, considering the future climate and temperature projections.

Reflections on a Century of Extreme Heat Event-Related Mortality Reporting in Canada

Climate change is causing more frequent and severe extreme heat events (EHEs) in Canada, resulting in significant loss of life. However, patterns across mortality reporting for historical EHEs have not been analyzed. To address this gap, we studied deaths in Canadian EHEs from 1936 to 2021, identifying trends and challenges. Our analysis revealed inconsistencies in mortality data, discrepancies between vulnerable populations identified, difficulties in determining the cause of death, and inconsistent reporting on social vulnerability indicators. We provide some observations that could help inform solutions to address the gaps and challenges, by moving toward more consistent and comprehensive reporting to ensure no population is overlooked. Accurately accounting for affected populations could help better target evidence-based interventions, and reduce vulnerability to extreme heat.

Impacts of the 2021 heat dome on emergency department visits, hospitalizations, and health system operations in three hospitals in Seattle, Washington

Objectives

Extreme heat events (EHEs) are associated with excess healthcare utilization but specific impacts on emergency department (ED) operations and throughput are unknown. In 2021, the Pacific Northwest experienced an unprecedented heat dome that resulted in substantial regional morbidity and mortality. The aim of this study was to examine its impact on ED utilization, unplanned hospitalization, and hospital operations in a large academic healthcare system.

Methods

Retrospective electronic medical records from three Seattle-area hospitals were used to compare healthcare utilization during the EHE compared to a pre-event reference period within the same month. Interrupted time series analysis was used to evaluate the association between EHE exposure and ED visits and hospitalizations. Metrics of ED crowding for the EHE were compared to the reference period using Student's t-tests and chi-squared tests. Additionally, multivariable Poisson regression was used to identify risk factors for heat-related illness and hospital admission.

Results

Interrupted time series analysis showed an increase of 21.7 ED visits per day (95% confidence interval [CI] = 14.7, 28.6) and 9.9 unplanned hospitalizations per day (95% CI = 8.3, 11.5) during the EHE, as compared to the reference period. ED crowding and process measures also displayed significant increases, becoming the most pronounced by day 3 of the EHE; the EHE was associated with delays in ED length of stay of 1.0 h (95% CI = 0.4, 1.6) compared to the reference period. Higher incidence rate ratios for heat-related illness were observed for patients who were older (incidence rate ratio [IRR] = 1.02; 95% CI = 1.01,1.03), female (IRR = 1.47; 95% CI = 1.06, 2.04), or who had pre-existing diabetes (IRR = 3.19; 95% CI = 1.47, 6.94).

Conclusions

The 2021 heat dome was associated with a significant increase in healthcare utilization including ED visits and unplanned hospitalizations. Substantial impacts on ED and hospital throughput were also noted. These findings contribute to the understanding of the role extreme heat events play on impacting patient outcomes and healthcare system function.

Effects of Daylong Exposure to Indoor Overheating on Thermal and Cardiovascular Strain in Older Adults: A Randomized Crossover Trial

BACKGROUND

Health agencies recommend that homes of heat-vulnerable occupants (e.g., older adults) be maintained below 24-28°C to prevent heat-related mortality and morbidity. However, there is limited experimental evidence to support these recommendations.

OBJECTIVE

To aid in the development of evidence-based guidance on safe indoor temperatures for temperate continental climates, we evaluated surrogate physiological outcomes linked with heat-related mortality and morbidity in older adults during simulated indoor overheating.

METHODS

Sixteen older adults [six women; median age: 72 y, interquartile range (IQR): 70-73 y; body mass index: 24.6   ( IQR :   22.1 - 27.0 )   kg / m 2 ] from the Ottawa, Ontario, Canada, region (warm summer continental climate) completed four randomized, 8-h exposures to conditions experienced indoors during hot weather in continental climates (e.g., Ontario, Canada; 64 participant exposures). Ambient conditions simulated an air-conditioned environment (22°C; control), proposed indoor temperature upper limits (26°C), and temperatures experienced in homes without air-conditioning (31°C and 36°C). Core temperature (rectal) was monitored as the primary outcome; based on previous recommendations, between-condition differences > 0.3 ° C were considered clinically meaningful.

RESULTS

Compared with 22°C, core temperature was elevated to a meaningful extent in 31°C [+ 0 . 7 ° C ; 95% confidence interval (CI): 0.5, 0.8] and 36°C (+ 0 . 9 ° C ; 95% CI: 0.8, 1.1), but not 26°C (+ 0 . 2 ° C , 95% CI: 0.0, 0.3). Increasing ambient temperatures were also associated with elevated heart rate and reduced arterial blood pressure and heart rate variability at rest, as well as progressive impairments in cardiac and blood pressure responses to standing from supine.

DISCUSSION

Core temperature and cardiovascular strain were not appreciably altered following 8-h exposure to 26°C but increased progressively in conditions above this threshold. These data support proposals for the establishment of a 26°C indoor temperature upper limit for protecting vulnerable occupants residing in temperate continental climates from indoor overheating. https://doi.org/10.1289/EHP13159.

The effects of attitudes, norms, and perceived control on the adaptation of elderly individuals and individuals with chronic health conditions to heatwaves

BACKGROUND

In this study, the theory of planned behaviour (TPB) was used to examine the determinants of the heat protection intentions and actions of elderly individuals and individuals with chronic health conditions. This is an important topic as understanding the motivations for adapting behaviours to heatwaves can inform the design of warning systems and awareness campaigns by public health authorities to mitigate the adverse effects of weather hazards on health.

METHODS

Three phone surveys were conducted in 2015 and 2016 to collect data on a large sample of individuals with increased vulnerability to heatwaves in the city of Longueuil, Canada. Prospective and panel fixed effects logit models for ordinal variables were used to analyse the factors that influenced heat protection intentions and actions.

RESULTS

Attitudes, norms, and perceived control have positive effects on intentions to adopt heatwave protection actions and intentions on the effective adoption of these preventive measures. The hypothesis according to which perceived control moderates the effect of attitudes and norms on intentions is rejected. In addition, the results suggest that elderly individuals are less likely than individuals in other age groups to adopt heat protection actions. Health conditions related to vulnerability to hot weather do not seem to significantly improve the adoption of heat protection behaviours.

CONCLUSIONS

The adoption of heatwave protection actions can be improved by public health interventions that influence attitudes and social norms related to heat protection behaviours and facilitate their adoption.

Body Core Temperature After Foot Immersion and Neck Cooling in Older Adults Exposed to Extreme Heat

This randomized study evaluates the hypothesis that foot immersion in cool water alone or with supplemental neck cooling mitigates increases in core temperature in older adults exposed to environmental conditions simulating deadly heat waves in North America.

Experimental research in environmentally induced hyperthermic older persons: A systematic quantitative literature review mapping the available evidence

The heat-related health burden is expected to persist and worsen in the coming years due to an aging global population and climate change. Defining the breadth and depth of our understanding of age-related changes in thermoregulation can identify underlying causes and strategies to protect vulnerable individuals from heat. We conducted the first systematic quantitative literature review to provide context to the historical experimental research of healthy older adults - compared to younger adults or unhealthy age matched cases - during exogenous heat strain, focusing on factors that influence thermoregulatory function (e.g. co-morbidities). We identified 4,455 articles, with 147 meeting eligibility criteria. Most studies were conducted in the US (39%), Canada (29%), or Japan (12%), with 71% of the 3,411 participants being male. About 71% of the studies compared younger and older adults, while 34% compared two groups of older adults with and without factors influencing thermoregulation. Key factors included age combined with another factor (23%), underlying biological mechanisms (18%), age independently (15%), influencing health conditions (15%), adaptation potential (12%), environmental conditions (9%), and therapeutic/pharmacological interventions (7%). Our results suggest that controlled experimental research should focus on the age-related changes in thermoregulation in the very old, females, those with overlooked chronic heat-sensitive health conditions (e.g. pulmonary, renal, mental disorders), the impact of multimorbidity, prolonged and cumulative effects of extreme heat, evidence-based policy of control measures (e.g. personal cooling strategies), pharmaceutical interactions, and interventions stimulating protective physiological adaptation. These controlled studies will inform the directions and use of limited resources in ecologically valid fieldwork studies.

Elegant Nematodes Improve Our Understanding of Human Neuronal Diseases, the Role of Pollutants and Strategies of Resilience

The prevalence of neurodegenerative disorders such as Alzheimer's and Parkinson's disease are rising globally. The role of environmental pollution in neurodegeneration is largely unknown. Thus, this perspective advocates exposome research in C. elegans models of human diseases. The models express amyloid proteins such as Aβ, recapitulate the degeneration of specifically vulnerable neurons and allow for correlated neurobehavioral phenotyping throughout the entire life span of the nematode. Neurobehavioral traits like locomotion gaits, rigidity, or cognitive decline are quantifiable and carefully mimic key aspects of the human diseases. Underlying molecular pathways of neurodegeneration are elucidated in pollutant-exposed C. elegans Alzheimer's or Parkinson's models by transcriptomics (RNA-seq), mass spectrometry-based proteomics and omics addressing other biochemical traits. Validation of the identified disease pathways can be achieved by genome-wide association studies in matching human cohorts. A consistent One Health approach includes isolation of nematodes from contaminated sites and their comparative investigation by imaging, neurobehavioral profiling and single worm proteomics. C. elegans models of neurodegenerative diseases are likewise well-suited for high throughput methods that provide a promising strategy to identify resilience pathways of neurosafety and keep up with the number of pollutants, nonchemical exposome factors, and their interactions.

Indoor overheating influences self-reported symptoms and mood-state in older adults during a simulated heatwave: Effects of mid-day cooling centre use

Public health agencies recommend that older adults without home air-conditioning visit cooling centres to mitigate physiological strain from high ambient temperatures during heat waves. However, there is little evidence regarding their influence on self-reported environmental symptoms and mood-state after returning to the heat.

METHODS

Forty adults (64-79 years) underwent a daylong laboratory-based indoor overheating simulation (9-hours, heat index: 37 °C) with (cooling, n = 20) or without (control, n = 20) a 2-hour air-conditioning intervention (hours 5-6). Mean skin and core temperature areas under the curve (AUC, hours 0-9) were used to assess cumulative thermal strain. Group differences in total symptom scores and subjective heat illness (68-item environmental symptoms questionnaire) as well as total mood disturbance and energy index (40-item profile of mood states questionnaire) were evaluated at end-heating (adjusted for pre-exposure scores).

RESULTS

Cooling reduced mean skin and core temperature AUCs by 4.0 [0.1, 0.8] and 1.6 [0.4, 2.8] °C·hour compared to control (both p < 0.048). However, at end-heating neither mean skin nor core temperatures differed between groups (both p > 0.999). Total symptom scores and subjective heat illness were 0.58-fold [0.44, 0.77] and 0.56-fold [0.40, 0.78] lower in the cooling compared to control group (both p < 0.001). Mood disturbance was 0.91-fold [0.83, 0.99] lower for cooling than control (p = 0.036), although energy index was not different between groups (p = 0.141).

CONCLUSION

Cooling centres can have sustained positive effects on perceived thermal strain and mood-state in older adults after returning to the heat. However, continued vigilance and use of appropriate countermeasures to mitigate physiological strain from indoor overheating should be encouraged as body temperatures can rapidly return to pre-cooling levels.

Changes in emergency department use in British Columbia, Canada, during the first 3 years of the COVID-19 pandemic

BACKGROUND

Previous studies have shown reductions in the volume of emergency department visits early in the COVID-19 pandemic, but few have evaluated the pandemic's impact over time or stratified analyses by reason for visits. We aimed to quantify such changes in British Columbia, Canada, cumulatively and during prominent nadirs, and by reason for visit, age and acuity.

METHODS

We included data from the National Ambulatory Care Reporting System for 30 emergency departments across BC from January 2016 to December 2022. We fitted generalized additive models, accounting for seasonal and annual trends, to the monthly number of visits to estimate changes throughout the pandemic, compared with the expected number of visits in the absence of the pandemic. We determined absolute and relative differences at various times during the study period, and cumulatively since the start of the pandemic until the overall volume of emergency department visits returned to expected levels.

RESULTS

Over the first 16 months of the pandemic, the volume of emergency department visits was reduced by about 322 300 visits, or 15% (95% confidence interval 12%-18%), compared with the expected volume. A sharp drop in pediatric visits accounted for nearly one-third of the reduction. The timing of the return to baseline volume of visits differed by subgroup. The largest and most sustained decreases were in respiratory-related emergency department visits, visits among children, visits among oldest adults and non-urgent visits. Later in the pandemic, we observed increased volumes of highest-urgency visits, visits among children and visits related to ear, nose and throat.

INTERPRETATION

We have extended evidence that the impact of the COVID-19 pandemic and associated mitigation strategies on emergency department visits in Canada was substantial. Both our findings and methods are relevant in public health surveillance and capacity planning for emergency departments in pandemic and nonpandemic times.

"In small places, close to home": Urban environmental impacts on child rights across four global cities

Urban environments influence child behaviours, exposures and experiences and may affect health, development, achievement and realization of fundamental human rights. We examined the status of eleven UN Convention on the Rights of the Child articles, in a multi-case study across four global cities. Within all study cities, children experienced unequal exposure to urban environmental risks and amenities. Many violations of child rights are related to car-based transportation systems and further challenged by pressures on urban systems from rapid population increases in the context of climate change. A child rights framework provides principles for a collective, multi-sectoral re-imagination of urban environments that support the human rights of all citizens.

Physiological responses to 9 hours of heat exposure in young and older adults. Part I: Body temperature and hemodynamic regulation

Aging is associated with an elevated risk of heat-related mortality and morbidity, attributed, in part, to declines in thermoregulation. However, comparisons between young and older adults have been limited to brief exposures (1-4 h), which may not adequately reflect the duration or severity of the heat stress experienced during heat waves. We therefore evaluated physiological responses in 20 young (19-31 yr; 10 females) and 39 older (61-78 yr; 11 females) adults during 9 h of rest at 40°C and 9% relative humidity. Whole body heat exchange and storage were measured with direct calorimetry during the first 3 h and final 3 h. Core temperature (rectal) was monitored continuously. The older adults stored 88 kJ [95% confidence interval (CI): 29, 147] more heat over the first 3 h of exposure (P = 0.006). Although no between-group differences were observed after 3 h [young: 37.6°C (SD 0.2°C) vs. older: 37.7°C (0.3°C); P = 0.216], core temperature was elevated by 0.3°C [0.1, 0.4] (adjusted for baseline) in the older group at hour 6 [37.6°C (0.2°C) vs. 37.9°C (0.2°C); P < 0.001] and by 0.2°C [0.0, 0.3] at hour 9 [37.7°C (0.3°C) vs. 37.8°C (0.3°C)], although the latter comparison was not significant after multiplicity correction (P = 0.061). Our findings indicate that older adults sustain greater increases in heat storage and core temperature during daylong exposure to hot dry conditions compared with their younger counterparts. This study represents an important step in the use of ecologically relevant, prolonged exposures for translational research aimed at quantifying the physiological and health impacts of hot weather and heat waves on heat-vulnerable populations.NEW & NOTEWORTHY We found greater increases in body heat storage and core temperature in older adults than in their younger counterparts during 9 h of resting exposure to hot dry conditions. Furthermore, the age-related increase in core temperature was exacerbated in older adults with common heat-vulnerability-linked health conditions (type 2 diabetes and hypertension). Impairments in thermoregulatory function likely contribute to the increased risk of heat-related illness and injury seen in older adults during hot weather and heat waves.

Urban heat island impacts on heat-related cardiovascular morbidity: A time series analysis of older adults in US metropolitan areas

Many United States (US) cities are experiencing urban heat islands (UHIs) and climate change-driven temperature increases. Extreme heat increases cardiovascular disease (CVD) risk, yet little is known about how this association varies with UHI intensity (UHII) within and between cities. We aimed to identify the urban populations most at-risk of and burdened by heat-related CVD morbidity in UHI-affected areas compared to unaffected areas. ZIP code-level daily counts of CVD hospitalizations among Medicare enrollees, aged 65-114, were obtained for 120 US metropolitan statistical areas (MSAs) between 2000 and 2017. Mean ambient temperature exposure was estimated by interpolating daily weather station observations. ZIP codes were classified as low and high UHII using the first and fourth quartiles of an existing surface UHII metric, weighted to each have 25% of all CVD hospitalizations. MSA-specific associations between ambient temperature and CVD hospitalization were estimated using quasi-Poisson regression with distributed lag non-linear models and pooled via multivariate meta-analyses. Across the US, extreme heat (MSA-specific 99th percentile, on average 28.6 °C) increased the risk of CVD hospitalization by 1.5% (95% CI: 0.4%, 2.6%), with considerable variation among MSAs. Extreme heat-related CVD hospitalization risk in high UHII areas (2.4% [95% CI: 0.4%, 4.3%]) exceeded that in low UHII areas (1.0% [95% CI: -0.8%, 2.8%]), with upwards of a 10% difference in some MSAs. During the 18-year study period, there were an estimated 37,028 (95% CI: 35,741, 37,988) heat-attributable CVD admissions. High UHII areas accounted for 35% of the total heat-related CVD burden, while low UHII areas accounted for 4%. High UHII disproportionately impacted already heat-vulnerable populations; females, individuals aged 75-114, and those with chronic conditions living in high UHII areas experienced the largest heat-related CVD impacts. Overall, extreme heat increased cardiovascular morbidity risk and burden in older urban populations, with UHIs exacerbating these impacts among those with existing vulnerabilities.

Impact of Playground Shade Structures on Ultraviolet Radiation Exposure and Physical Activity among Children at a Childcare Facility

Skin cancer is the most common cancer in Canada, and rates continue to rise. While sunscreen and protective clothing remain critical strategies to reduce skin cancer risk, shade is generally the most effective way to control exposure. There remains a lack of data, particularly in British Columbia (BC), demonstrating the extent to which shade availability reduces ultraviolet radiation (UVR) exposure in a real-world setting and the potential impacts of shade provision on physical activity. We evaluated the impact of shade structures on UVR exposure and physical activity at a Vancouver-area childcare center with an outdoor play area with limited existing shade. 22 children, aged 3-5 years, participated in the study. Three removable shade sails were installed in the outdoor play space, and UVR and physical activity measurements were collected during the spring, summer, and fall months. Ultraviolet B (UVB) radiation data was measured using UVB dosimeters, and physical activity data was measured using accelerometers. Data were collected during each season over a total of four days-two days with shade sails installed and two days with shade sails removed. Overall, with shade installation, UVR exposures and physical activity levels among children were reduced by 50% and 20%, respectively. This study supports the use of shade sails to significantly reduce UVR exposures among preschool-aged children in BC; however, the potential for decreased physical activity from shade sails should be further explored in future research.

A multiscale analysis of heatwaves and urban heat islands in the western U.S. during the summer of 2021

Extreme heat events are occurring more frequently and with greater intensity due to climate change. They result in increased heat stress to populations causing human health impacts and heat-related deaths. The urban environment can also exacerbate heat stress because of man-made materials and increased population density. Here we investigate the extreme heatwaves in the western U.S. during the summer of 2021. We show the atmospheric scale interactions and spatiotemporal dynamics that contribute to increased temperatures across the region for both urban and rural environments. In 2021, daytime maximum temperatures during heat events in eight major cities were 10-20 °C higher than the 10-year average maximum temperature. We discuss the temperature impacts associated with processes across scales: climate or long-term change, the El Niño-Southern Oscillation, synoptic high-pressure systems, mesoscale ocean/lake breezes, and urban climate (i.e., urban heat islands). Our findings demonstrate the importance of scale interactions impacting extreme heat and the need for holistic approaches in heat mitigation strategies.

Efficacy of Cooling Centers for Mitigating Physiological Strain in Older Adults during Daylong Heat Exposure: A Laboratory-Based Heat Wave Simulation

BACKGROUND

Health agencies, including the U.S. Centers for Disease Control and Prevention and the World Health Organization, recommend that heat-vulnerable older adults without home air-conditioning should visit cooling centers or other air-conditioned locations (e.g., a shopping mall) during heat waves. However, experimental evidence supporting the effectiveness of brief air-conditioning is lacking.

OBJECTIVE

We evaluated whether brief exposure to an air-conditioned environment, as experienced in a cooling center, was effective for limiting physiological strain in older adults during a daylong laboratory-based heat wave simulation.

METHODS

Forty adults 64-79 years of age underwent a 9-h simulated heat wave (heat index: 37°C) with (cooling group, n=20) or without (control group, n=20) a cooling intervention consisting of 2-h rest in an air-conditioned room (∼23°C, hours 5-6). Core and skin temperatures, whole-body heat exchange and storage, cardiovascular function, and circulating markers of acute inflammation were assessed.

RESULTS

Core temperature was 0.8°C (95% CI: 0.6, 0.9) lower in the cooling group compared with the control group at the end of the cooling intervention (p<0.001; hour 6), and it remained 0.3°C (95% CI: 0.2, 0.4) lower an hour after returning to the heat (p<0.001; hour 7). Despite this, core temperatures in each group were statistically equivalent at hours 8 and 9, within ±0.3°C (p≤0.005). Cooling also acutely reduced demand on the heart and improved indices of cardiovascular autonomic function (p≤0.021); however, these outcomes were not different between groups at the end of exposure (p≥0.58).

DISCUSSION

Brief air-conditioning exposure during a simulated heat wave caused a robust but transient reduction in core temperature and cardiovascular strain. These findings provide important experimental support for national and international guidance that cooling centers are effective for limiting physiological strain during heat waves. However, they also show that the physiological impacts of brief cooling are temporary, a factor that has not been considered in guidance issued by health agencies. https://doi.org/10.1289/EHP11651.

Too hot! Preventing, recognizing and managing heat injury in children

Climate change-related extreme heat events leading to public health emergencies are increasing in Canada and expected to affect more regions, more frequently and for longer time periods. Children, city dwellers and marginalized populations are amongst the most vulnerable to morbidity and mortality related to extreme heat. Paediatricians can provide caregivers and families with advice to minimize risks as well as advocate for safer city planning and harm mitigation strategies.

Hot weather and death related to acute cocaine, opioid and amphetamine toxicity in British Columbia, Canada: a time-stratified case-crossover study

BACKGROUND

Previous research has shown that cocaine-associated deaths occur more frequently in hot weather, which has not been described for other illicit drugs or combinations of drugs. The study objective was to evaluate the relation between temperature and risk of death related to cocaine, opioids and amphetamines in British Columbia, Canada.

METHODS

We extracted data on all deaths with cocaine, opioid or amphetamine toxicity recorded as an underlying or contributing cause from BC vital statistics for 1998-2017. We used a time-stratified case-crossover design to estimate the effect of temperature on the risk of death associated with acute drug toxicity during the warmer months (May through September). Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated for each 10°C increase in the 2-day average maximum temperature at the residential location.

RESULTS

We included 4913 deaths in the analyses. A 10°C increase in the 2-day average maximum temperature was associated with an OR of 1.43 (95% CI 1.11-1.86) for deaths with only cocaine toxicity recorded (n = 561), an OR of 1.15 (95% CI 0.99-1.33) for deaths with opioids only (n = 1682) and an OR of 1.11 (95% CI 0.60-2.04) for deaths with amphetamines only (n = 133). There were also elevated effects when toxicity from multiple drugs was recorded. Sensitivity analyses showed differences in the ORs by sex, by climatic region, and when the location of death was used instead of the location of residence.

INTERPRETATION

Increasing temperatures were associated with higher odds of death due to drug toxicity, especially for cocaine alone and combined with other drugs. Targeted interventions are necessary to prevent death associated with toxic drug use during hot weather.

Chronic Diseases Associated With Mortality in British Columbia, Canada During the 2021 Western North America Extreme Heat Event

Western North America experienced an unprecedented extreme heat event (EHE) in 2021, characterized by high temperatures and reduced air quality. There were approximately 740 excess deaths during the EHE in the province of British Columbia, making it one of the deadliest weather events in Canadian history. It is important to understand who is at risk of death during EHEs so that appropriate public health interventions can be developed. This study compares 1,614 deaths from 25 June to 02 July 2021 with 6,524 deaths on the same dates from 2012 to 2020 to examine differences in the prevalence of 26 chronic diseases between the two groups. Conditional logistic regression was used to estimate the odds ratio (OR) for each chronic disease, adjusted for age, sex, and all other diseases, and conditioned on geographic area. The OR [95% confidence interval] for schizophrenia among all EHE deaths was 3.07 [2.39, 3.94], and was larger than the ORs for other conditions. Chronic kidney disease and ischemic heart disease were also significantly increased among all EHE deaths, with ORs of 1.36 [1.18, 1.56] and 1.18 [1.00, 1.38], respectively. Chronic diseases associated with EHE mortality were somewhat different for deaths attributed to extreme heat, deaths with an unknown/pending cause, and non-heat-related deaths. Schizophrenia was the only condition associated with significantly increased odds of EHE mortality in all three subgroups. These results confirm the role of mental illness in EHE risk and provide further impetus for interventions that target specific groups of high-risk individuals based on underlying chronic conditions.

The effect modification of extreme temperatures on mental and behavior disorders by environmental factors and individual-level characteristics in Canada

OBJECTIVE

Ambient extreme temperatures have been associated with mental and behavior disorders (MBDs). However, few studies have assesed whether vulnerability factors such as ambient air pollution, pre-existing mental health conditions and residential environmental factors increase susceptibility. This study aims to evaluate the associations between short-term variations in outdoor ambient extreme temperatures and MBD-related emergency department (ED) visits and how these associations are modified by vulnerability factors.

METHODS

We conducted a case-crossover study of 9,958,759 MBD ED visits in Alberta and Ontario, Canada made between March 1st, 2004 and December 31st, 2020. Daily average temperature was assigned to individual cases with ED visits for MBD using gridded data at a 1 km × 1 km spatial resolution. Conditional logistic regression was used to estimate associations between extreme temperatures (i.e., risk of ED visit at the 2.5th percentile temperature for cold and 97.5th percentile temperature for heat for each health region compared to the minimal temperature risk) and MBD ED visits. Age, sex, pre-existing mental health conditions, ambient air pollution (i.e. PM_2.5, NO₂ and O₃) and residential environmental factors (neighborhood deprivation, residential green space exposure and urbanization) were evaluated as potential effect modifiers.

RESULTS

Cumulative exposure to extreme heat over 0-5 days (odds ratio [OR] = 1.145; 95% CI: 1.121-1.171) was associated with ED visits for any MBD. However, cumulative exposure to extreme cold was associated with lower risk of ED visits for any MBD (OR = 0.981; 95% CI: 0.976-0.987). We also found heat to be associated with ED visits for specific MBDs such as substance use disorders, dementia, neurotic disorders, schizophrenia and personality behavior disorder. Individuals with pre-existing mental health conditions, those exposed to higher daily concentrations of NO₂ and O₃ and those residing in neighborhoods with greater material and social deprivation were at higher risk of heat-related MBD ED visits. Increasing tree canopy coverage appeared to mitigate risks of the effect of heat on MBD ED visits.

CONCLUSIONS

Findings provide evidence that the impacts of heat on MBD ED visits may vary across different vulnerability factors.

The unprecedented Pacific Northwest heatwave of June 2021

In late June 2021 a heatwave of unprecedented magnitude impacted the Pacific Northwest region of Canada and the United States. Many locations broke all-time maximum temperature records by more than 5 °C, and the Canadian national temperature record was broken by 4.6 °C, with a new record temperature of 49.6 °C. Here, we provide a comprehensive summary of this event and its impacts. Upstream diabatic heating played a key role in the magnitude of this anomaly. Weather forecasts provided advanced notice of the event, while sub-seasonal forecasts showed an increased likelihood of a heat extreme with lead times of 10-20 days. The impacts of this event were catastrophic, including hundreds of attributable deaths across the Pacific Northwest, mass-mortalities of marine life, reduced crop and fruit yields, river flooding from rapid snow and glacier melt, and a substantial increase in wildfires-the latter contributing to landslides in the months following. These impacts provide examples we can learn from and a vivid depiction of how climate change can be so devastating.

The heat wave knowledge, awareness, practice and behavior scale: Scale development, validation and reliability

Heat waves are extreme weather and climate events that threaten public health by increasing morbidity and mortality. To reduce the health effects of heat waves, it is necessary to increase the knowledge level of the public, conduct awareness and protection activities and monitor these activity outcomes. The present study aimed to develop and validate a Turkish language scale of heat wave knowledge, awareness, practice and behavior for Turkish nationality. After item generation and creating dimensions, content validity analysis was performed. To evaluate the validity and reliability of the knowledge construct, the difficulty index, discriminant index and Kuder Richardson 20 (KR20) were used. The validity and reliability of the awareness, practice and behavior constructs were evaluated with exploratory and confirmatory factor analyses, and Cronbach's alpha was used. The 15 items had a good difficulty, discrimination index and KR20 in the knowledge construct. The 14 items were yielded in EFA; 13 items were retained in CFA, and Cronbach's alpha values of 0.878, 0.768, 0.855, and 0.858 were obtained for total items, practice, awareness and behavior, respectively. Eventually, a Turkish language scale was developed that is reliable and valid for assessing heat wave knowledge, awareness, practice and behavior.

Estimating the Burden of Heat-Related Illness Morbidity Attributable to Anthropogenic Climate Change in North Carolina

Climate change is known to increase the frequency and intensity of hot days (daily maximum temperature ≥30°C), both globally and locally. Exposure to extreme heat is associated with numerous adverse human health outcomes. This study estimated the burden of heat-related illness (HRI) attributable to anthropogenic climate change in North Carolina physiographic divisions (Coastal and Piedmont) during the summer months from 2011 to 2016. Additionally, assuming intermediate and high greenhouse gas emission scenarios, future HRI morbidity burden attributable to climate change was estimated. The association between daily maximum temperature and the rate of HRI was evaluated using the Generalized Additive Model. The rate of HRI assuming natural simulations (i.e., absence of greenhouse gas emissions) and future greenhouse gas emission scenarios were predicted to estimate the HRI attributable to climate change. Over 4 years (2011, 2012, 2014, and 2015), we observed a significant decrease in the rate of HRI assuming natural simulations compared to the observed. About 3 out of 20 HRI visits are attributable to anthropogenic climate change in Coastal (13.40% [IQR: -34.90,95.52]) and Piedmont (16.39% [IQR: -35.18,148.26]) regions. During the future periods, the median rate of HRI was significantly higher (78.65%: Coastal and 65.85%: Piedmont), assuming a higher emission scenario than the intermediate emission scenario. We observed significant associations between anthropogenic climate change and adverse human health outcomes. Our findings indicate the need for evidence-based public health interventions to protect human health from climate-related exposures, like extreme heat, while minimizing greenhouse gas emissions.

Public Health Measures to Address the Impact of Climate Change on Population Health-Proceedings from a Stakeholder Workshop

BACKGROUND

The World Health Organization identified climate change as the 21st century's biggest health threat. This study aimed to identify the current knowledge base, evidence gaps, and implications for climate action and health policymaking to address the health impact of climate change, including in the most underserved groups.

METHODS

The Horizon-funded project ENBEL ('Enhancing Belmont Research Action to support EU policy making on climate change and health') organised a workshop at the 2021-European Public Health conference. Following presentations of mitigation and adaptation strategies, seven international researchers and public health experts participated in a panel discussion linking climate change and health. Two researchers transcribed and thematically analysed the panel discussion recording.

RESULTS

Four themes were identified: (1) 'Evidence is key' in leading the climate debate, (2) the need for 'messaging about health for policymaking and behaviour change' including health co-benefits of climate action, (3) existing 'inequalities between and within countries', and (4) 'insufficient resources and funding' to implement national health adaptation plans and facilitate evidence generation and climate action, particularly in vulnerable populations.

CONCLUSION

More capacity is needed to monitor health effects and inequities, evaluate adaptation and mitigation interventions, address current under-representations of low- or middle-income countries, and translate research into effective policymaking.

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.

Cumulative Impacts of Diverse Land Uses in British Columbia, Canada: Application of the "EnviroScreen" Method

(1) Objectives: Cumulative impacts refer to the legacies of land use decisions on environmental, community and health values. New integrative impact assessment tools are required to assess cumulative impacts on diverse values to meet sustainability goals in the 21st century. In this contribution, the CalEnviroScreen methodology-a screening tool capable of merging environmental, socioeconomic and health data-is applied to Local Health Areas in British Columbia, Canada. (2) Methods: The CalEnviroScreen is a method that standardizes environmental, socioeconomic and health data to depict an indicator's percentile rank in the distribution of all units of analysis. The method combines indicators to measure four dimensions of pressure: environmental exposures, environmental effects, socioeconomic conditions, and sensitive populations (i.e., health outcomes). We create two versions of EnviroScreen: one following the CalEnviroScreen suite of indicators, and another that uses nuanced indicators to approximate the realities of industrial land uses present in British Columbia. BCEnviroScreen scores are plotted by race/ethnicity to understand potential racial inequities in cumulative exposures. (3) Results: The BCEnviroScreen has a greater likelihood of quantifying the cumulative impacts of diverse industries and land uses present across resource-dependent parts of the province, relative to the more urban-centric CalEnviroScreen indicator suite. Analyzing the distribution of BCEnviroScreen scores by race/ethnicity suggests that visible minority populations may be inequitably exposed to cumulative impacts in BC. (4) Conclusion: EnviroScreen tools hold significant potential to influence Canadian environmental health policy. This research demonstrates the applicability of the tool to British Columbia and other jurisdictions, illustrates how indicators can be tailored to better represent regional context, and shows how the tool can be used to screen for potential environmental health injustices.