Tag: heat waves

Categories : Environmental EffectsTags :

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

On By ModernMedia
Photo by Ketut Subiyanto

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 : Cardiovascular Disease Environmental EffectsTags :

Extreme Heat Threatens Cardiovascular Health

On By ModernMedia
Photo from Olivier Collett on Unsplash
Photo from Olivier Collett on Unsplash


With South Africa’s summer being expected to be both wetter and hotter this year, there is a greater risk of adverse cardiovascular incidents, especially for adults with pre-existing cardiovascular diseases. Experts writing in the Canadian Journal of Cardiology discuss how extreme heat affects cardiovascular health, why health professionals should care and what recommendations they can make to minimise consequences.

Extreme heat events are predicted to become longer, more common and more severe. Some 70 000 heat-related deaths occurred during the 2003 European heatwave. Risk factors for heat-related hospitalisation include age, chronic illnesses, social isolation, some medications, and lack of access to air conditioning. Among chronic illnesses, cardiovascular diseases are often identified as a risk factor for heat-related hospitalisation and death.

The Intergovernmental Panel on Climate Change (IPCC) recently reported that global temperatures are rising at a greater rate than previously projected, and that the number of extreme heat days will significantly increase across most land regions,” said senior author Daniel Gagnon, PhD, University of Montreal. “Although we don’t yet fully understand the reasons, people with cardiovascular disease are at greater risk of hospitalisations and death during extreme heat events.”

The researchers reviewed studies and noted a consistent association between extreme heat and increased risk of adverse cardiovascular outcomes. An examination of reviews and meta-analyses on the effect of extreme heat on adverse cardiovascular outcomes showed that heatwaves significantly increase mortality risk from ischaemic heart disease, stroke, and heart failure.

“Although the effects of extreme heat on adverse cardiovascular events have been explained in the context of heatstroke, many events occur without heatstroke, and the mechanisms of these events in the absence of heatstroke remain unclear,” observed Dr Gagnon. “It is likely that heat exposure increases myocardial oxygen needs.”

One possibility is that heat exposure puts excessive strain on the heart for individuals with heart disease and that heat exposure increases the risk of blood clots forming within cardiac blood vessels.

The authors propose that preventive strategies should aim to reduce the extent of hyperthermia and dehydration. In Canada, heat-health warnings systems act as a first line of defence by raising awareness of upcoming heat events and recommending strategies to minimise possible heat complications. For example, heat warnings are issued 18-24 hours before a heat event in Ontario and Québec, when ambient temperature will remain above 30°C for a minimum of two days. Public advisories include identifying the signs of heat stress, ensuring people drink adequate amounts of cold fluid or seeking an air-conditioned environment – though for many people, this is not an option.

Recent research supports electric fan use, skin wetting and immersing the feet in tap water as simple methods to stay cool during extreme heat events. “Air conditioning is the most effective strategy that can be recommended since it effectively removes the heat stimulus and minimises the risk of adverse cardiovascular outcomes,” commented Dr Gagnon. “However, less than one third of global households own air conditioning.”

More studies are needed to explain why extreme heat is linked to increased risk of adverse cardiovascular outcomes; the effect of cardiovascular medication on the human body’s physiological responses during heat exposure; the best cooling strategies in heat waves for individuals with CVD; and safe environmental limits for outdoor exercise in individuals with heart disease.

“Cardiovascular health professionals need to be aware of the negative consequences of extreme heat on cardiovascular health. A better awareness and understanding of the cardiovascular consequences of extreme heat, and of the measures to take to prevent and mitigate adverse events, will help us all assess the risk and optimize the care of patients exposed to an increasingly warm climate,” concluded Dr Gagnon.

Source: Elsevier