Tag: extreme heat

Categories : Environmental EffectsTags :

Study Tallies Heatwave Deaths over Recent Decades

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Between 1990 and 2019, more than 150 000 deaths around the globe were associated with heatwaves each year, according to a new study published May 14 in PLOS Medicine by Yuming Guo of Monash University, Australia, and colleagues.

Heatwaves, periods of extremely high ambient temperature that last for a few days, can impose overwhelming thermal stress on the human body.

Studies have previously quantified the effect of individual heatwaves on excess deaths in local areas, but have not compared these statistics around the globe over such a prolonged period.

In the new study, researchers used data from the Multi-Country Multi-City (MCC) Collaborative Research Network that included daily deaths and temperatures from 750 locations across 43 countries.

With the MCC data, the researchers estimated excess heatwave deaths around the world spanning 1990 to 2019 and mapped the variance in these deaths across continents.

During the warm seasons from 1990 to 2019, heatwave-related excess deaths accounted for 153 078 deaths per year, a total of 236 deaths per 10 million residents or 1% of global deaths.

While Asia had the highest number of estimated deaths, Europe had the highest population-adjusted rate, at 655 deaths per 10 million residents.

A substantial burden of estimated deaths was seen in southern and eastern Europe as well as the area between Northern Africa, the Arabian Peninsula and Southern Asia.

At the national level, Greece, Malta, and Italy had the highest excess death ratios.

Overall, the largest estimated rates of heatwaves deaths were seen in areas with dry climates and lower-middle incomes.

Understanding the regional disparity of heatwave-related mortality is key to planning local adaptation and risk management towards climate change.

“Heatwaves are associated with substantial mortality burden that varies spatiotemporally over the globe in the past 30 years,” the authors say.

“These findings indicate the potential benefit of government actions to enhance health sector adaptation and resilience, accounting for inequalities across communities.”

The authors add, “In the context of climate change, it is crucial to address the unequal impacts of heatwaves on human health. This necessitates a comprehensive approach that not only tackles immediate health risks during heatwaves but also implements long-term strategies to minimize vulnerability and inequality. The strategies include: climate change mitigation policy, heat action plans (e.g., heat early warning system), urban planning and green structure, social support program, healthcare and public health services, education awareness, and community engagement and participation.”

Provided by PLOS

Categories : Environmental Effects Respiratory DiseasesTags :

Extreme Heat Linked to Children’s Asthma Hospital Visits

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For children seeking care at a California urban paediatric health centre, extreme heat events were associated with increased asthma hospital visits, according to research published at the ATS 2024 International Conference.

“We found that both daily high heat events and extreme temperatures that lasted several days increased the risk of asthma hospital visits,” said corresponding author Morgan Ye, MPH, research data analyst, Division of Pulmonary and Critical Care Medicine, University of California, San Francisco School of Medicine. “Understanding the impacts of climate-sensitive events such as extreme heat on a vulnerable population is the key to reducing the burden of disease due to climate change.”

Ms Ye and colleagues looked at 2017-2020 electronic health records from the UCSF Benioff Children’s Hospital Oakland, which included data on asthma hospital visits by patients of the hospital, some of whom are from Benioff Oakland’s Federally Qualified Health Center, and demographics including patients’ zip codes. They used data from the PRISM Climate Group of Oregon State University to determine the timing of daily maximum (daytime heat waves) and minimum (nighttime heat waves) for each zip code. The researchers restricted their analyses to the region’s warm season (June to September). To evaluate the potential range of effects of different heat wave measurements, they used 18 different heat wave definitions, including the 99th, 97.5th and 95th percentile of the total distribution of the study period for one, two or three days.

They designed the study in a way that allowed them to determine the association between each heat wave definition and a hospital visit. They repeated the analysis for Bay Area and Central California zip codes.

The team discovered that daytime heat waves were significantly associated with 19% higher odds of children’s asthma hospital visits, and longer duration of heat waves doubled the odds of hospital visits. They did not observe any associations for night-time heat waves.

According to Ye, “We continue to see global temperatures rise due to human-generated climate change, and we can expect a rise in health-related issues as we observe longer, more frequent and severe heat waves. Our research suggests that higher temperatures and increased duration of these high heat days are associated with increased risk of hospital visits due to asthma. Children and families with lower adaptation capacity will experience most of the burden. Therefore, it is important to obtain a better understanding of these heat-associated health risks and susceptible populations for future surveillance and targeted interventions.”

The authors note that past research has suggested positive associations between extreme heat and asthma, but findings regarding hospitalisations and emergency room visits have been conflicting. Additionally, many other studies have focused on respiratory hospitalizations and not hospitalizations for asthma, specifically, and have not included or had a focus on children. This study is also unique because it investigated the effect of daily high temperatures but also the effects of persistent extreme temperatures.

The San Francisco Bay Area and California overall are unique areas of interest because the state is considered a coastal region with less prevalence of cooling units, such as air conditioners. While temperatures may not reach the extremes experienced in other parts of the country, this study demonstrates that even milder extreme heat temperatures may significantly impact health. These effects are more pronounced in climate-susceptible populations, including children and those who are medically vulnerable, such as those served by the urban paediatric health centre in this study. The authors hope these study results will lead to more equitable health outcomes and reduce racial/ethnic disparities observed in climate-sensitive events.

“These results can be used to inform targeted actions and resources for vulnerable children and alleviate health-related stress during heat waves,” they conclude.

Source: American Thoracic Society

Categories : Cardiovascular Disease Environmental EffectsTags :

Hot Days may Drive Inflammation and Accelerate Cardiovascular Disease

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Short-term exposure to higher heat may increase inflammation and interfere with normal immune system functions in the body, which may, in turn, increase susceptibility to infections and accelerate the progression of cardiovascular disease, according to preliminary research be presented at the American Heart Association’s Epidemiology and Prevention – Lifestyle and Cardiometabolic Scientific Sessions 2024, March 18-21.

An inflammatory response that is longstanding (lasting weeks to months) or that occurs in healthy tissues is damaging and plays a key role in the build-up of plaque in the arteries. This may lead to atherosclerosis. Heat waves are known to promote inflammation, however, studies examining air temperature and biomarkers of inflammation have had mixed results.

“Most research only considers temperature as the exposure of interest, which may not be adequate to capture a person’s response to heat,” said lead study author Daniel W. Riggs, PhD, an assistant professor of medicine at the University of Louisville. “In our study, we used alternative measurements of heat in relation to multiple markers of inflammation and immune response in the body to investigate the short-term effects of heat exposure and produce a more complete picture of its health impact.”

Participants visited study sites in Louisville, during the summer months for a blood test, and researchers analysed the blood for multiple markers of immune system function. The researchers then examined associations between the markers of immune system function and heat levels, including temperature, net effective temperature (which factors in relative humidity, air temperature and windspeed) and the Universal Thermal Climate Index (UTCI) on that day. UTCI is a thermo-physiological model developed by the International Society of Biometeorology Commission that factors in temperature, humidity, wind speed and ultraviolet radiation levels, which was used to evaluate participant’s physical comfort.

The analysis found:

  • For every 5°F (2.8°C) increase in UTCI (in this study, the equivalent of going from a day with no thermal stress to a day with moderate thermal stress, Riggs said), there was an increase in blood levels of key inflammatory markers: monocytes (4.2%), eosinophils (9.5%), natural killer T-cells (9.9%) and tumour necrosis factor-alpha (7.0%). These immune molecules indicate activation of the body’s innate immune system, which spurs a fast and non-specific inflammatory response throughout the body to protect against pathogens and injury.
  • A decrease in B-cells (-6.8%), indicating the body’s adaptive immune system that remembers specific viruses and germs and creates antibodies to fight them, was lowered.
  • A lesser impact on the immune system was found when heat was measured by average 24-hour temperature or by net effective temperature, which incorporates humidity and wind but not sunshine.

“Our study participants only had minor exposure to high temperatures on the day of their blood test, however, even minor exposure may contribute to changes in immune markers,” Riggs said. “With rising global temperatures, the association between heat exposure and a temporarily weakened response from the immune system is a concern because temperature and humidity are known to be important environmental drivers of infectious, airborne disease transmission. Thus, during the hottest days of summer people may be at higher risk of heat exposure, they may also be more vulnerable to disease or inflammation.”

Adults over 60 years and adults with existing cardiovascular disease are particularly at risk for heat-related cardiovascular events and deaths, Riggs explained.

“It’s important for physicians to communicate with patients about the risk of adverse health effects from heat exposure. For example, cardiologists could conduct customised consultations and assessments to increase patient awareness about their susceptibility to the effects of high temperatures. Also, changes to treatment regimens may be important to consider to address other risks. For example, some medications could make people more susceptible to heat-related illness or some may not be as effective when the body is exposed to high temperatures,” Riggs said.

Source: American Heart Association

Categories : Environmental EffectsTags :

Air Conditioning Kept Heat-related Deaths Down in Spain – for Those who Could Afford it

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Air conditioning and heating systems have contributed considerably to reducing mortality linked to extreme temperatures in Spain, according to a new observational study. The findings, published in Environment International, provide valuable insights for designing policies to adapt to climate change.

Rising temperatures but lower mortality

Spain, like many parts of the world, has experienced rising temperatures in recent decades, with the average annual mean temperature increasing at an average rate of 0.36°C per decade.

The warming trend is even more pronounced in the summer months (0.40°C per decade). Surprisingly, this increase in temperature has coincided with a progressive reduction in mortality associated with heat.

In addition, cold-related mortality has also decreased.

“Understanding the factors that reduce susceptibility to extreme temperatures is crucial to inform health adaptation policies and to combat the negative effects of climate change,” says first author of the study, Hicham Achebak, researcher at ISGlobal and Inserm (France) and holder of a Marie Sklodowska-Curie Postdoctoral Fellowship from the European Commission.

Effective societal adaptations

In this study led by the Barcelona Institute for Global Health (ISGlobal), Achebak and colleagues analysed the demographic and socioeconomic factors behind the observed reduction in heat and cold-related mortality, despite rising temperatures.

They found that the increase in air conditioning (AC) prevalence in Spain was associated with a reduction in heat-related mortality, while the rise in heating prevalence was associated with a decrease in cold-related mortality.

Specifically, AC was found to be responsible for about 28.6% of the decline in deaths due to heat and 31.5% of the decrease in deaths due to extreme heat between the late 1980s and the early 2010s.

Heating systems contributed significantly, accounting for about 38.3% of the reduction in cold-related deaths and a substantial 50.8% decrease in extreme cold-related fatalities during the same period.

The decrease in mortality due to cold would have been larger had there not been a demographic shift towards a higher proportion of people aged over 65, who are more susceptible to cold temperatures.

The authors conclude that the reduction in heat-related mortality is largely the result of the country’s socioeconomic development over the study period, rather than specific interventions such as heat-wave warning systems.

Four decades of data

For the statistical analysis, the research team collected data on daily mortality (all causes) and weather (temperature and relative humidity) for 48 provinces in mainland Spain and the Balearic Islands, between January 1980 and December 2018.

These data were then linked to 14 indicators of context (demographic and socioeconomic variables such as housing, income and education) for these populations over the same period.

Implications for climate adaptation

The results of the study extend previous findings on heat-related mortality in Spain and underscore the importance of air conditioning and heating as effective adaptation measures to mitigate the effects of heat and cold.

“However, we observed large disparities in the presence of AC across provinces. AC is still unaffordable for many Spanish households,” says Achebak.

The authors also point out that the widespread use of AC could further contribute to global warming depending on the source of electricity generation, which is why other cooling strategies, such as expanding green and blue spaces in cities, are also needed.

“Our findings have important implications for the development of adaptation strategies to climate change. They also inform future projections of the impact of climate change on human health,” concludes Joan Ballester, ISGlobal researcher and study coordinator.

Source: Barcelona Institute for Global Health (ISGlobal)

Categories : Environmental EffectsTags :

Europe’s Heat-related Deaths in 2022 may Exceed 70 000

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The burden of heat-related mortality during the summer of 2022 in Europe may have exceeded 70 000 deaths according to a study led by the Barcelona Institute for Global Health (ISGlobal). The authors of the study, published in The Lancet Regional Health – Europe, revised upwards initial estimates of the mortality associated with record temperatures in 2022 on the European continent.

In an earlier study, the same team used epidemiological models applied to weekly temperature and mortality data in 823 regions in 35 European countries and estimated the number of heat-related premature deaths in 2022 to be 62 862. In that study, the authors acknowledged that the use of weekly data would be expected to underestimate heat-related mortality, and pointed out that daily time-series data are required to accurately estimate the impact of high temperatures on mortality.

The objective of the new study was to develop a theoretical framework that could quantify the errors inherent to aggregated data, such as weekly and monthly temperature and mortality time-series. Models based on temporally aggregated data are useful because the data are available in real-time, allowing analysis of the health hazard within a few days. The researchers aggregated daily temperatures and mortality records from 147 regions in 16 European countries. They then analysed and compared the estimates of heat- and cold-related mortality by different levels of aggregation: daily, weekly, 2-weekly and monthly.

Analysis revealed differences in epidemiological estimates according to the time scale of aggregation. In particular, it was found that weekly, 2-weekly and monthly models underestimated the effects of heat and cold as compared to the daily model, and that the degree of underestimation increased with the length of the aggregation period. Specifically, for the period 1998–2004, the daily model estimated an annual cold and heat-related mortality of 290 104 and 39 434 premature deaths, respectively, while the weekly model underestimated these numbers by 8.56% and 21.56%, respectively.

“It is important to note that the differences were very small during periods of extreme cold and heat, such as the summer of 2003, when the underestimation by the weekly data model was only 4.62%,” explains Joan Ballester Claramunt, the ISGlobal researcher who leads the European Research Council’s EARLY-ADAPT project.

The team used this theoretical framework to revise the mortality burden attributed to the record temperatures experienced in 2022 in their earlier study. According to the calculations made using the new methodological approach, that study underestimated the heat-related mortality by 10.28%, which would mean that the actual heat-related mortality burden in 2022, estimated using the daily data model, was 70,066 deaths, and not 62,862 deaths as originally estimated.

Weekly data to analyse short-term effects of temperatures

“In general, we do not find models based on monthly aggregated data useful for estimating the short-term effects of ambient temperatures,” explains Ballester. “However, models based on weekly data do offer sufficient precision in mortality estimates to be useful in real-time practice in epidemiological surveillance and to inform public policies such as, for example, the activation of emergency plans for reducing the impact of heat waves and cold spells.”

It is an advantage in this area of research to be able to use weekly data since investigators often encounter bureaucratic obstacles that make it difficult or impossible to design large-scale epidemiological studies based on daily data. According to Ballester, when daily data is not available, the use of weekly data, which are easily accessible for Europe in real time, is a solution that can offer “a good approximation of the estimates obtained using the daily data model.”

Source: Barcelona Institute for Global Health (ISGlobal)

Categories : Environmental EffectsTags :

Increase in Excessively Hot Nights Will Raise Mortality Rate

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With the number of excessively hot nights expected to double due to climate change, it is predicted that their associated mortality rate will rise by up to 60% by the end of the century, according to the latest research published in published in The Lancet Planetary Health.

Ambient heat during the night may interrupt the normal physiology of sleep, leading to immune system damage and a higher risk of cardiovascular disease, chronic illnesses, inflammation and mental health conditions. The average intensity of hot night events will nearly double by 2090, from 20.4℃ to 39.7℃ across 28 cities from east Asia, increasing the burden of disease due to excessive heat that disrupts normal sleeping patterns.

This is the first study to estimate the impact of hotter nights on climate change-related mortality risk. The findings show that the burden of mortality could be significantly higher than estimated by average daily temperature increase, suggesting that warming from climate change could have a troubling impact, even under restrictions from the Paris Climate Agreement.

“The risks of increasing temperature at night were frequently neglected,” said study co-author Yuqiang Zhang, PhD, a climate scientist in the Department of Environmental Sciences and Engineering at the Gillings School. “However, in our study, we found that the occurrences of hot night excess are projected to occur more rapidly than the daily mean temperature changes. The frequency and mean intensity of hot nights would increase more than 30% and 60% by the 2100s, respectively, compared with less than 20% increase for the daily mean temperature.”

The team estimated the mortality due to excess heat in 28 cities in China, South Korea and Japan between 1980 and 2015 and applied it to two climate change modelling scenarios that aligned with carbon-reduction scenarios adapted by the respective national governments.

Through this model, the team was able to estimate that between 2016 and 2100, the risk of death from excessively hot nights would increase nearly six-fold. This prediction is much higher than the mortality risk from daily average warming suggested by climate change models.

“From our study, we highlight that, in assessing the disease burden due to non-optimum temperature, governments and local policymakers should consider the extra health impacts of the disproportional intra-day temperature variations. A more complete health risk assessment of future climate change can help policymakers for better resource allocation and priority setting,” said Haidong Kan, PhD, who is a professor at Fudan University in China and the study’s corresponding author.

In this study, the authors also found that regional differences in temperature accounted for many of the variances in nighttime temperature, and areas with the lowest average temperature were projected to have the largest warming potential.

“To combat the health risk raised by the temperature increases from climate change, we should design efficient ways to help people adapt,” said Dr Zhang. “Locally, heat during the night should be taken into account when designing the future heatwave warning system, especially for vulnerable populations and low-income communities who may not be able to afford the additional expense of air conditioning. Also, stronger mitigation strategies, including global collaborations, should be considered to reduce future impacts of warming.”

Since the study only included 28 cities from three countries, Dr Zhang said that “extrapolation of these results to the whole East Asia region or other regions should be cautious. Currently, based on these findings, authors are trying to extend the analysis to a global dataset. Then we could have a global picture of the deadly nighttime heat on health under climate change scenarios.”

Source: University of North Carolina at Chapel Hill

Categories : Cardiovascular DiseaseTags :

Beta Blockers and Antiplatelet Drugs Tied to Heat-related MI Risk

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During hot weather events, people taking beta blockers and antiplatelet medications such as aspirin could be at increased risk of a myocardial infarction (MI), amplifying the risk already present from hot weather.

A new study published in Nature Cardiovascular Research found that, among people suffering non-fatal MI associated with hot weather, a greater portion are taking these heart drugs.

“Patients taking these two medications have higher risk,” said Assistant Professor Kai Chen, first author of the study. “During heat waves, they should really take precautions.”

External environmental factors like air pollution and cold weather can trigger MIs, and there is growing evidence to suggest that hot weather can do so, too. But epidemiologists are still working to identify which groups of people are most vulnerable to these environmental extremes.

The authors looked at 2494 cases sourced from a registry, in which individuals experienced a non-fatal MI in Augsburg, Germany during the hot-weather months (May–September) between 2001 and 2014.

In previous research, they had shown that exposure to either heat or cold made heart attacks more likely, and they calculated that heat-related MI rates would rise once the planet has warmed by 2–3°C.

The current study built on that research by examining patients’ medication use prior to their MI.

They analysed the data in a way that let patients serve as their own controls, by comparing heat exposure on the day of the MI versus the same days of the week within the same month. That is, if a person had an NI on the third Thursday in June, the authors compared their temperature exposure that day to their temperature exposure on other, “control” Thursdays in June.

It turned out that users of beta-blockers or antiplatelet medications were likelier to have an MI during the hottest days compared to control days. Antiplatelet medication use was associated with a 63% increase in risk and beta-blockers with a 65% increase. People taking both drugs had a 75% higher risk. Non-users of those medications were not more likely to have a heart attack on hot days.

When researchers compared younger patients (25–59 years) to older ones (60–74 years), they found, as expected, that the younger ones were a healthier group, with lower rates of coronary heart disease. Yet younger patients taking beta-blockers and antiplatelet medications were more susceptible to heat-related heart attack than older patients, despite the older ones having more heart disease.

Another clue that these two medication types may render people more vulnerable is that, other heart medications generally didn’t show a connection to heat-related heart attacks. An exception was statins, which taken by younger people, were associated with an over threefold risk of a heart attack on hot days.

“We hypothesise that some of the medications may make it hard to regulate body temperature,” Asst Prof Chen said. He plans to find out why in future studies.

The results suggest that as climate change progresses, heart attacks might become a greater hazard to some people with cardiovascular disease.

Source: Yale School of Public Health

Categories : Environmental EffectsTags :

Extreme Heat Health Risks Are Higher for Younger Adults

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A new study in the US has found that complications from extreme heat appear to be more pronounced among young and middle-aged adults than older adults.

Extreme heat poses an increasing threat to the public, due to the continued effects of climate change. Although the adverse health impacts of heat have been well documented among older adults, less is known about the potential impacts of heat on young and middle-aged adults.

Published in the BMJ, the study examined the relationship between extreme temperatures and emergency department (ED) visits, and found that days of extreme heat were associated with an increase risk of ED visits for any cause, heat-related illness, renal disease, and mental disorders among all adults, but the strongest association was found among adults ages 18-64.

Prior research on heat’s health impacts have mostly focused on mortality or hospital admissions among seniors. This study is the first national-scale assessment of extreme heat effects on adults of all ages, measured with ED visits.

“Many illnesses that lead to utilisation of the ED do not lead to hospitalisation because they can be treated in a short amount of time, particularly among the younger adult population,” said study senior author Gregory Wellenius, professor of environmental health and director of the Program on Climate and Health at SPH. “By looking at emergency room visits, we aimed to obtain a more comprehensive picture of the true burden of disease that might be attributed to the days of high heat.”

Prof Wellenius and colleagues analysed healthcare claims data to quantify the risk of ED visits for any cause and for heat-associated conditions during the warm season (between May and September) from 2010 to 2019.

For the study, the researchers analysed claims data among 74 million adults, including more than 22 million ED visits. They found that days of extreme heat (varying by location, but averaging about 34°C), were associated with a 66% greater risk of ED visits for heat-related illness, as well as a 30% increased risk for renal disease, compared to ED visits on cooler days. But the risk according to extreme heat varied by age. A day of extreme heat was associated with a 10.3% higher risk of ED visits among people ages 45 to 54 years old, compared to a 3.6% higher risk among those older than 75.

“Younger adults may be at greater risk of exposure to extreme heat, particularly among workers that spend substantial time outdoors,” says study lead author Shengzhi Sun, research scientist in the Department of Environmental Health at SPH. “Younger adults may also not realise that they too can be at risk on days of extreme heat.”

Prior studies had shown that people in US counties with lower warm-season temperatures still experience higher risks of heat-related complications.
“While extreme heat threatens everyone’s health, this study provides further evidence that it is especially dangerous in regions with cooler climates that may be less adapted to heat,” says study co-author Kate Weinberger, assistant professor at the University of British Columbia’s School of Population and Public Health. “As temperatures continue to rise due to climate change, the implementation of heat adaptation measures in these regions will be critically important.”

According to the researchers, many of these heat-related complications can be prevented through policy changes that reduce exposure to heat, or improve people’s susceptibility and adaptivity to heat.

“By looking at emergency department visits for different causes and for several age groups, we were able to characterise with accuracy the varying impact on health on different populations,” said study co-author, Professor Francesca Dominici. “An important goal of this study is to provide actionable information to clinicians and public health experts regarding how to prevent these emergency department visits, also considering that we can anticipate when these extreme heat events are likely to occur.”

Source: Boston University