Heat Warning System Research Articles

Climate change and heatwaves: Improving Ontario’s harmonized heat warning and information system

Created in 2015, Ontario’s Harmonized Heat Warning and Information System (HWIS) has never been evaluated for its processes and implementation. This paper evaluated the HWIS’s processes using a guidance report published by the World Meteorological Organization and World Health Organization. It also evaluated public health units’ implementation of the HWIS using information found on their websites. The results showed the HWIS lacks monthly threshold values, evaluation processes, and a wider action plan. In the implementation of the HWIS, public health units have failed to post on their websites all 15 heat health messages and locations and hours of local interventions. Six recommendations are made to Public Health Ontario, public health units, and Ontario Ministry of Health to improve on the processes and implementation of the HWIS. As climate change increases the frequency and intensity of heatwaves, an improved HWIS can reduce the incidence of heat-related illness and deaths in Ontario.

Explorative Assessment of the Temperature-Mortality Association to Support Health-Based Heat-Warning Thresholds: A National Case-Crossover Study in Switzerland.

Defining health-based thresholds for effective heat warnings is crucial for climate change adaptation strategies. Translating the non-linear function between heat and health effects into an effective threshold for heat warnings to protect the population is a challenge. We present a systematic analysis of heat indicators in relation to mortality. We applied distributed lag non-linear models in an individual-level case-crossover design to assess the effects of heat on mortality in Switzerland during the warm season from 2003 to 2016 for three temperature metrics (daily mean, maximum, and minimum temperature), and various threshold temperatures and heatwave definitions. Individual death records with information on residential address from the Swiss National Cohort were linked to high-resolution temperature estimates from 100 m resolution maps. Moderate (90th percentile) to extreme thresholds (99.5th percentile) of the three temperature metrics implied a significant increase in mortality (5 to 38%) in respect of the median warm-season temperature. Effects of the threshold temperatures on mortality were similar across the seven major regions in Switzerland. Heatwave duration did not modify the effect when considering delayed effects up to 7 days. This nationally representative study, accounting for small-scale exposure variability, suggests that the national heat-warning system should focus on heatwave intensity rather than duration. While a different heat-warning indicator may be appropriate in other countries, our evaluation framework is transferable to any country.

Comparison of various heat waves definitions and the burden of heat-related mortality in France: Implications for existing early warning systems

IntroductionIn France, a heat warning system (HWS) has been implemented almost two decades ago and rely on some official heat wave (HW) definitions. However, no study has compared the burden associated with a large set of alternative HW definitions to the official definitions. Such comparison could be particularly helpful to identify HW conditions for which effective HWS would minimize the health burden across various geographical contexts and possibly update thresholds to trigger HWS. The aim of this study is to identify (and rank) definitions that drive the highest health burden in terms of mortality to inform future HWS across multiple cities in France. MethodsBased on weather data for 16 French cities, we compared the two official definitions used in France to: i) the Excess Heat Factor (EHF) used in Australia, and ii) 18 alternative hypothetical HW definitions based on various combinations of temperature metrics, intensity, and duration. Propensity score matching and Poisson regressions were used to estimate the effect of each HW exposure on non-accidental mortality for the May–September period from 2000 to 2015. ResultsThe associations between HW and mortality differed greatly depending on the definition. The greatest burden of heat was 1,055 (95% confidence interval “CI”: [856; 1,302]) deaths per summer and was obtained with the EHF. The EHF identified HW with 2.46 (95% CI: [1.92; 3.58]) or 8.18 (95% CI: [6.63; 10.61]) times the global burden at the national level obtained with the climatological indicator of the French national weather service and the HW indicator of the French national HWS, respectively and was the most impactful definition pattern for both temperate oceanic and Mediterranean climate types. ConclusionIdentifying the set of extreme heat conditions that drive the highest health burden in a given geographical context is particularly helpful when designing or updating heat early warning systems.

Impact of Ontario's Harmonized Heat Warning and Information System on emergency department visits for heat-related illness in Ontario, Canada: a population-based time series analysis.

Ontario's Harmonized Heat Warning and Information System (HWIS) brings harmonized, regional heat warnings and standard heat-health messaging to provincial public health units prior to periods of extreme heat. Was implementation of the harmonized HWIS in May 2016 associated with a reduction in emergency department (ED) visits for heat-related illness in urban locations across Ontario, Canada? We conducted a population-based interrupted time series analysis from April 30 to September 30, 2012-2018, using administrative health and outdoor temperature data. We used autoregressive integrated moving average models to examine whether ED rates changed following implementation of the harmonized HWIS, adjusted for maximum daily temperature. We also examined whether effects differed in heat-vulnerable groups (≥65 years or <18 years, those with comorbidities, those with a recent history of homelessness), and by heat warning region. Over the study period, heat alerts became more frequent in urban areas (6 events triggered between 2013 and 2015 and 14 events between 2016 and 2018 in Toronto, for example). The mean rate of ED visits was 47.5 per 100,000 Ontarians (range 39.7-60.1) per 2-week study interval, with peaks from June to July each year. ED rates were particularly high in those with a recent history of homelessness (mean rate 337.0 per 100,000). Although rates appeared to decline following implementation of HWIS in some subpopulations, the change was not statistically significant at a population level(rate 0.04, 95% CI: -0.03 to 0.1, p=0.278). In urban areas across Ontario, ED encounters for heat-related illness may have declined in some subpopulations following HWIS, but the change was not statistically significant. Efforts to continually improve HWIS processes are important given our changing Canadian climate.

Assessing mortality risk attributable to high ambient temperatures in Ahmedabad, 1987 to 2017

BackgroundStudies on high temperatures and mortality have not focused on underdeveloped tropical regions and have reported the associations of different temperature metrics without conducting model selection. MethodsWe collected daily mortality and meteorological data including ambient temperatures and humidity in Ahmedabad during summer, 1987–2017. We proposed two cross-validation (CV) approaches to compare semiparametric quasi-Poisson models with different temperature metrics and heat wave definitions. Using the fittest model, we estimated heat-mortality associations among general population and subpopulations. We also conducted separate analyses for 1987–2002 and 2003–2017 to evaluate temporal heterogeneity. FindingsThe model with maximum and minimum temperatures and without heat wave indicator gave the best performance. With this model, we found a substantial and significant increase in mortality rate starting from maximum temperature at 42 °C and from minimum temperature at 28 °C: 1 °C increase in maximum and minimum temperatures at lag 0 were associated with 9.56% (95% confidence interval [CI]: 6.64%, 12.56%) and 9.82% (95% CI: 6.33%, 13.42%) increase in mortality risk, respectively. People aged ≥65 years and lived in South residential zone where most slums were located, were more vulnerable. We observed flatter increases in mortality risk associated with high temperatures comparing the period of 2003–2017 to 1987–2002. InterpretationThe analyses provided better understanding of the relationship of high temperatures with mortality in underdeveloped tropical regions and important implications in developing heat warning system for local government. The proposed CV approaches will benefit future scientific work.

Evolving heat waves characteristics challenge heat warning systems and prevention plans.

This paper analyses how recent trends in heat waves impact heat warning systems. We performed a retrospective analysis of the challenges faced by the French heat prevention plan since 2004. We described trends based on the environmental and health data collected each summer by the French heat warning system and prevention plan. Major evolutions of the system were tracked based on the evaluations organized each autumn with the stakeholders of the prevention plan. Excess deaths numbering 8000 were observed during heat waves between 2004 and 2019, 71% of these between 2015 and 2019. We observed major changes in the characteristics, frequency and the geographical spread of heat waves since 2015. Feedbacks led to several updates of the warning system such as the extension of the surveillance period. They also revealed that risk perception remained limited among the population and the stakeholders. The sharp increase in the number of heat warnings issued per year since 2015 challenges the acceptability of the heat warnings. Recent heat waves without historical equivalent interfere with the development of evidence-based prevention strategies. The growing public health impacts heat waves emphasize the urgent need to act to adapt the population, at different levels of intervention, from individual comportments to structural modifications. A specific attention should be given to increase the resources allocated to the evaluation and the management of heat-related risks, especially considering the needs to catch with the rapid rhythm of the changing climate.Supplementary InformationThe online version contains supplementary material available at 10.1007/s00484-021-02123-y.

Revealing an Integrative Mechanism of Cognition, Emotion, and Heat-Protective Action of Older Adults

This study aims to provide an in-depth understanding of what motivates older adults to take their adaptive behaviors during extreme heat events. Elaborating the mediating role of emotion in human behaviors, we empirically explore an interrelationship between individuals’ cognition, emotion, and heat-protective action in response to heat warning system alarms. Through face-to-face surveys and structural equation modeling, this study reveals that an increased level of cognition about climate change, heat waves, and local policy measures leads to emotional responses such as concern and worry, and consequently encourages people to comply with heat-related public guidelines. Furthermore, we also consider individuals’ pre-existing health conditions and their previous experiences of heat-related illnesses together with the emotional factors. The role of emotion in mediating between cognition and heat-protective action is much greater than in mediating between pre-existing health conditions and heat-protective action. We conclude that policy interventions to educate older adults can effectively increase the likelihood of individual compliance with the relevant preventive measures beyond their individual health and experiences.

Evaluating Mortality Response Associated with Two Different Nordic Heat Warning Systems in Riga, Latvia.

Background and objectives: Progressing climate change is accompanied by a worldwide increase in the intensity, frequency, and duration of heat wave events. Research has shown that heat waves are an emerging public health problem, as they have a significant impact on mortality. As studies exploring this relationship are scarce for Latvia, this study aims to investigate the short-term associations between heat waves and all-cause mortality as well as cause-specific mortality, during the summer months (May-September) in Riga. Materials and Methods: An ecological time series study using daily reported mortality and temperature data from Riga between 2009 and 2015 was employed. Heat waves were defined based on the categories of the Latvian and Swedish heat warning system. Using a Quasi-Poisson regression, the relationships between heat waves and all-cause as well as cause-specific mortality were investigated. Results: Heat waves in Riga were associated with a 10% to 20% increase in the risk of all-cause mortality, depending on the applied heat wave definition, compared to days with normal temperature. In addition, heat-related mortality was found to increase significantly in the ≥65 age group between 12% and 22% during heat waves. In terms of cause-specific mortality, a significant increase of approximately 15% to 26% was observed for cardiovascular mortality. No significant associations were found between heat waves and respiratory or external causes of mortality. Conclusion: These results indicate that there are short-term associations between heat waves and all-cause as well as cardiovascular mortality in Riga and that heat waves therefore represent a public health problem in this Baltic city.

Developing a harmonized heat warning and information system for Ontario: a case study in collaboration

BackgroundHeat wave early warning systems help alert decision-makers and the public to prepare for hot weather and implement preventive actions to protect health. Prior to harmonization, public health units across Ontario either used independent systems with varying methodologies for triggering and issuing public heat warnings or did not use any system. The federal government also issued heat warnings based on different criteria. During heat events, adjacent public health units in Ontario and the federal government would routinely call heat warnings at different times with separate public messages, leading to confusion. This article describes the collaborative process and key steps in developing a harmonized Heat Warning and Information System (HWIS) for Ontario.SettingPublic health units across Ontario, Canada, collaborated with the federal and provincial government to develop the harmonized HWIS for Ontario.InterventionIn 2011, stakeholders identified the need to develop a harmonized system across Ontario to improve heat warning services, warning criteria, and health messaging. Through a 5-year process facilitated by a non-governmental organization, the three levels of government collaborated to establish the Ontario HWIS.OutcomesThe province-wide HWIS was implemented in 2016 with the Ontario Ministry of Health and Long-Term Care’s release of the harmonized HWIS Standard Operating Practice, which outlined the notification and warning process.ImplicationsThe lessons learned could help spur action in other provinces and jurisdictions internationally in the development of similar health evidence-based warning systems, including in particular those for protecting public health during extreme heat events.

At which temperature do the deleterious effects of ambient heat “kick-in” to affect all-cause mortality? An exploration of this threshold from an eastern Indian city

ABSTRACTDespite experiencing hot weathers, limited studies from India explored relationships between ambient heat and health. We studied associations between heat and all-cause mortality to estimate heat threshold(s) affecting health, and examine other affecting dimensions. We conducted time-series analysis with daily maximum temperature and all-cause mortality data of Bhubaneswar city (March–July, 2007–2017), and explored their interactions. Mortality risks rose when daily maximum temperatures were >36.2°C (lower threshold), and even more when >40.5°C (upper threshold). Every degree above36.2°C increased the mortality risk by 2% (mortality rate ratio: 1.02; 95% CI 1.01, 1.03). The effects of maximum temperature increased on days when minimum temperatures were >25.6°C (median). The effect of heat was immediate and lasted for 0–1 day with no lagged effect. Two temperature thresholds with varying mortality risks provided an opportunity for a graded heat warning system. The accentuation of the deleterious effects of heat by the higher minimum temperature calls for its inclusion in the heat warning system in future.

New approach to identifying proper thresholds for a heat warning system using health risk increments

BackgroundA critical adaptation strategy for reducing heat-related health risk under climate change is to establish a heat warning system with a proper threshold that requires evaluation of heat-health relationships using empirical data. ObjectivesThis work presents a new approach to selecting proper health-based thresholds for a heat warning system which are different from thresholds of heat-health relationship. MethodsThe proposed approach examined heat-health relationships through analyzing 15 years of health records with a modified generalized additive model (GAM), compared risk ratio increments (RRIs) of threshold candidates against a reference, assessed frequency of days above these candidates, and presented results graphically for easy communication. The candidate with the maximum RRI and proper occurring frequency is potentially the best threshold. Three heat indicators, including wet-bulb globe temperature (WBGT), temperature (T), and apparent temperature (AT), as well as three health outcomes, including all-cause mortality, heat-related hospital admissions, and heat-related emergency visits were evaluated. ResultsRisk ratios for all three health outcomes showed a consistent rising trend with increasing threshold candidates for all three heat indicators among different age and gender groups. WBGT had the most obvious increasing trend of RRIs with the three health outcomes. The maximum RRI was observed in heat-related emergency visits (242%), followed by heat-related hospital admissions (73%), and all-cause mortality (9%). The RRIs assessed for the three health outcomes pointed to the same thresholds, 33.0 °C, 34.0 °C, and 37.5 °C for WBGT, T, and AT, respectively. The number of days above these thresholds and for warning to be issued ranged between 0 and 7 days during 2000–2014. DiscussionThis study demonstrated a new approach to determining heat-warning thresholds with different heat indicators and health outcomes. The proposed approach provides a straightforward, feasible, and flexible scientific tool that assists the authorities around the world in selecting a proper threshold for a heat warning system.

The effect of hot days on occupational heat stress in the manufacturing industry: implications for workers\u2019 well-being and productivity

Climate change is expected to exacerbate heat stress at the workplace in temperate regions, such as Slovenia. It is therefore of paramount importance to study present and future summer heat conditions and analyze the impact of heat on workers. A set of climate indices based on summer mean (Tmean) and maximum (Tmax) air temperatures, such as the number of hot days (HD: Tmax above 30 °C), and Wet Bulb Globe Temperature (WBGT) were used to account for heat conditions in Slovenia at six locations in the period 1981–2010. Observed trends (1961–2011) of Tmean and Tmax in July were positive, being larger in the eastern part of the country. Climate change projections showed an increase up to 4.5 °C for mean temperature and 35 days for HD by the end of the twenty-first century under the high emission scenario. The increase in WBGT was smaller, although sufficiently high to increase the frequency of days with a high risk of heat stress up to an average of a third of the summer days. A case study performed at a Slovenian automobile parts manufacturing plant revealed non-optimal working conditions during summer 2016 (WBGT mainly between 20 and 25 °C). A survey conducted on 400 workers revealed that 96% perceived the temperature conditions as unsuitable, and 56% experienced headaches and fatigue. Given these conditions and climate change projections, the escalating problem of heat is worrisome. The European Commission initiated a program of research within the Horizon 2020 program to develop a heat warning system for European workers and employers, which will incorporate case-specific solutions to mitigate heat stress.

Valuing deaths or years of life lost? Economic benefits of avoided mortality from early heat warning systems

The study aims to explore the main drivers influencing the economic appraisal of heat warning systems by integrating epidemiological modelling and benefit-cost analysis. To shed insights on heat wave mortality valuation, we consider three valuation schemes: (i) a traditional one, where the value of a statistical life (VSL) is applied to both displaced and premature mortality; (ii) an intermediate one, with VSL applied for premature mortality and value of a life year (VOLY) for displaced mortality; and (iii) a conservative one, where both premature and displaced mortality are quantified in terms of loss of life expectancy, and then valued using the VOLY approach. When applying these three schemes to Madrid (Spain), we obtain a benefit-cost ratio varying from 12 to 3700. We find that the choice of the valuation scheme has the largest influence, whereas other parameters such as attributable risk, displaced mortality ratio, or the comprehensiveness and effectiveness of the heat warning system are less influential. The results raise the question of which is the most appropriate approach to value mortality in the context of heat waves, given that the lower bound estimate for the benefit-cost ratio (option iii using VOLY) is up to two orders of magnitude lower than the value based on the traditional VSL approach (option i). The choice of the valuation methodology has significant implications for public health authorities at the local and regional scale, which becomes highly relevant for locations where the application of the VOLY approach could lead to benefit-cost ratios significantly lower than 1. We propose that specific metrics for premature and displaced VOLYs should be developed for the context of heat waves. Until such values are available, we suggest testing the economic viability of heat warning systems under the three proposed valuation schemes (i–iii) and using values for VOLY commonly applied in air pollution as the health end points are similar. Lastly, periodical reassessment of heat alert plans should be performed by public health authorities to monitor their long-term viability and cost-effectiveness.

Relevance of Heat Health Actions Plans for Preventive Public Health in Germany

Heat waves are among the extreme weather events and represent a growing health hazard for the population in Europe. According to the current climate studies, the probability of an increase and intensification of heat waves has been increasing for years. Particularly affected by exposure to unusually high heat are people whose organism is already weakened by age or illness. As the share of senior citizens in Germany continues to rise as a result of demographic change, the health effects of heat waves are gaining in importance. Heat-induced morbidity and mortality can be effectively countered by information provision and timely initiation of preventive measures. The heat wave of the summer of 2003, which killed around 70000 people across Europe, led to the establishment of national heat warning systems and / or hot weather plans in much of Europe. In Germany, the heat warning system of the German Weather Service was set up nationwide in 2005. Thus, a 2-stage warning process can be comprehensively and timely inform people of an imminent heat wave, whereupon appropriate preventive measures can be initiated. In addition, it is recommended to establish a heat action plan which, in addition to heat warning, also takes into account comprehensive health intervention measures. This article outlines the background, significance and structure of a heat action plan according to the World Health Organization (WHO). This is based on the guidance document prepared in 2008 and the supplementary documents of the years 2009 and 2011. In order to ensure sustainable protection against heat-related health hazards, the World Health Organization (WHO) recommends the introduction of a national heat action plan for its Member States. There are fundamental differences between a heat warning system and a heat action plan. While the warning of a brief heat period is the central task of the heat warning system, the heat action plan follows an integrative approach that combines short, medium and long-term health protection measures within a common framework.

Evaluation of a heat warning system in Adelaide, South Australia, using case-series analysis

BackgroundHeatwave warning systems aim to assist in reducing health effects during extreme heat. Evaluations of such systems have been limited. This study explored the effect of a heatwave warning programme...

The Performance of the National Weather Service Heat Warning System against Ground Observations and Satellite Imagery

Deadly heat waves are increasing with climate change. Public forecasts and warnings are a primary public health strategy for dealing with such extreme weather events; however, temperatures can vary widely within the administrative units used to issue warnings, particularly across urban landscapes. The emergence of more frequent and widely distributed sources of urban temperature data provide the opportunity to investigate the specificity of the current National Weather Service (NWS) warnings and to improve their accuracy and precision. In this work, temperatures from distributed public weather stations, NWS heat advisories and warnings, and land surface temperature imagery throughout two large metropolitan areas, Atlanta and Chicago, during the 2006–2012 summers are considered. We investigate the spatial variability of hazardous temperatures and their agreement against NWS advisories. Second, we examine the potential for thermal imagery to replicate National Weather Service heat warnings. Observations from weather stations exhibit varying degrees of agreement with NWS advisories. The level of agreement varied by station and was not found to be associated with the station’s proximate land cover. Air temperatures estimated from satellite imagery correspond with NWS Advisory status regionally and may enable creating more refined public warnings regarding hazardous temperatures and protective actions

Heat waves and mortality in Frankfurt am Main, Germany, 2003-2013: what effect do heat-health action plans and the heat warning system have?

Following the heat wave of August 2003 that caused over 70,000 fatalities in Western Europe, heat-health action plans (HHAP) and heat warning systems were implemented in many European countries, including Germany. The effect of these preventive measures (informing the population as well as nursing and medical personnel) on excess mortality during heat waves in Frankfurt am Main, Germany, is studied, taking into account newly published data on a modifying effect of air pollution on heat mortality. Mortality data comprising all deaths registered in the city of Frankfurt was obtained from the statistical state office; air temperature and air pollution data in Frankfurt Ost were obtained from the Hessian state office for environment and geology. SPSS Version 15 was used for statistical analysis (bivariate and partial correlations, nonparametric tests/Kruskal-Wallis, and Mann-Whitney test). Temperature data as well as air pollution and daily mortality exhibited extreme values in summer 2003 compared to the summer periods 2004-2013. Never again were such levels of temperature and air pollution reached. In 2003, excess mortality was 78%, and as high as 113% among the population aged >80 years. During the heat wave of 2010, the total excess mortality was 23% (significant) and 38% in the population aged >80 years, while during heat waves in 2006 and 2013 no significant increase in total mortality was seen (total excess mortality 12% and 4%; not significant). Lower excess mortality could be seen in Frankfurt am Main during heat waves following the implementation of HHAP and the heat warning system. This might be an effect of the measures implemented by the HHAP to reduce heat mortality. However, it cannot be ruled out that this might also be an effect of shorter heat wave periods and lower air pollution in the subsequent years. Therefore, further efforts are needed to improve the resilience of the population, especially the elderly population, to better cope with heat waves.

A simple indicator to rapidly assess the short-term impact of heat waves on mortality within the French heat warning system

We propose a simple method to provide a rapid and robust estimate of the short-term impacts of heat waves on mortality, to be used for communication within a heat warning system. The excess mortality during a heat wave is defined as the difference between the observed mortality over the period and the observed mortality over the same period during the N preceding years. This method was tested on 19 French cities between 1973 and 2007. In six cities, we compared the excess mortality to that obtained using a modelling of the temperature-mortality relationship. There was a good agreement between the excess mortalities estimated by the simple indicator and by the models. Major differences were observed during the most extreme heat waves, in 1983 and 2003, and after the implementation of the heat prevention plan in 2006. Excluding these events, the mean difference between the estimates obtained by the two methods was of 13 deaths [1:45]. A comparison of mortality with the previous years provides a simple estimate of the mortality impact of heat waves. It can be used to provide early and reliable information to stakeholders of the heat prevention plan, and to select heat waves that should be further investigated.

Climate Change and Human Health in China

Climate Change and Human Health in China

Choice of Temperature Thresholds for the French Heat Warning System

Choice of Temperature Thresholds for the French Heat Warning System