Researchers advocate for the use of heat stress indices in the notification of harmful heat waves.

Over 20,000 additional deaths in Spain, France, Germany, and Great Britain in the summer of 2022 were thought to have been caused by extremely hot weather. Preventive measures and adequate communication of dangerous conditions take on special significance in the context of global warming, when climate models indicate that extreme heat waves are likely to increase in both frequency and magnitude.

Researchers from the Barcelona Institute for Global Health (ISGlobal) and the London School of Hygiene and Tropical Medicine (LSHTM) warn in a brief communication that was published in npj Climate and Atmospheric Science that relying solely on expected temperatures when communicating dangerous heat wave conditions may not be sufficient to inform people about the true health risks. To better convey the effects of extreme heat stress conditions, the team advocates for the widespread use of so-called heat stress indices, which take into account other meteorological factors like humidity in addition to temperature.

“It is the broader set of meteorological conditions that can affect one’s response to outdoor heat—beginning with the ambient temperature, as well as the humidity of the surrounding air, the prevailing wind conditions, exposure to direct sun versus being in shade, and finally the total duration of exposure to such conditions,”

Malcolm Mistry, from the London School of Hygiene and Tropical Medicine (LSHTM).

“The more extensive arrangement of meteorological circumstances can influence one’s reaction to outside warmth— beginning from the encompassing temperature, as well as the moistness of the encompassing air, the predominant breeze conditions, openness to the immediate sun as opposed to being in concealment, and lastly, the all-out term of openness to such circumstances,” says Malcolm Mistry, from the London School of Cleanliness and Tropical Medication (LSHTM) and Ca’ Foscari College of Venice, and a co-creator of the review. “The actual danger posed by ongoing heat waves might not always be conveyed when only the expected maximum temperatures are communicated. For instance, a similar surrounding temperature of 35°C can be awkward at low moistness, but perilous to human wellbeing at high stickiness, in any event, for a brief timeframe.”

Different heat stress indices have been developed to describe the impact of meteorological conditions on the human body, including the point at which the conditions experienced can become a threat to human health, despite the fact that each person’s threshold of resistance to heat varies according to a number of individual factors. A portion of the better-realized models are humidex (Hu), obvious temperature (AT), wet bulb globe temperature (WBGT), heat list (Hello), and general warm environment record (UTCI). This is especially significant considering the supposed “sticky intensity waves,” which are supposed to turn out to be more successive as a result of environmental change.

Different impressions of ‘peril zones’
The group investigated late record-breaking heat waves in Europe, North America, and Asia and analyzed the guides of the greatest everyday temperatures with the most extreme day-to-day heat pressure files (humidex and indoor wet bulb globe temperature). It was not always the case that the regions with the highest temperatures were also the ones where the heat indices showed the highest risk of heat stress.

For instance, during the intensity waves in Europe in June and July 2019, records show that central and north-eastern Spain encountered the most elevated temperatures. However, when the heat stress indices were calculated, the researchers discovered that France, Belgium, and the Netherlands had the most severe conditions, with an excess mortality rate of 2,500 deaths each.

The extreme heat wave that occurred in June 2021 in western Canada and the northwest United States was another case that was mentioned. Heat stress indices revealed that Canadian provinces like Alberta, the Northwest Territories, and British Columbia also experienced dangerous conditions, with the latter recording 600 heat-related deaths. The highest temperatures were recorded in the states of Washington and Oregon.

Reassuringly, heat records are by and large progressively carried out in weather conditions figures by the meteorological services all over the planet. “What is still missing is having heat indices communicated to the population in a regular manner, as it is traditionally done using temperatures,” states lead author Ivana Cvijanovic. Some examples include humidex in Canada, UTCI in Germany, and heat index in the United States. The scientific community could help with this by agreeing on which heat index is best to communicate and which danger levels to use.”

One more occasion the group took a gander at was the significant intensity wave that hit India and Pakistan in May 2022, when temperatures over 50°C were recorded. By and by, the intensity files uncovered risk zones that were not restricted to those with the most elevated temperatures. ” “We need to do everything we can to be as well prepared as possible to deal with them,” says Xavier Rodó, head of ISGlobal’s Climate and Health program and one of the authors of the study. “Episodes of extreme heat that push humans to the edge of survival, like the one recorded in India and Pakistan in May 2022, are likely to become more frequent, as climate models highlight.

“Unfortunately, health data from this heat wave was not available, and it would certainly be helpful to the scientific and medical communities to both better understand the nature and extent of the effects of mega heat waves and to educate us on how to prepare for such outcomes,” the statement reads.

“Improved protocols for action during heat waves are required, according to lessons learned from the most recent major heat waves. A clear chain of command is required after the meteorological warning has been issued. The specialists need to act speedily and know when to close schools or stop outside sports exercises, open cooling places for socially weak populations, and guarantee an adequate crisis reaction,” says Ivana Cvijanovic.

“It is also very important to educate the general public about how to behave during heat waves. Creating a “no-one-left-behind” culture in which people check on their elderly neighbors or anyone who appears to be vulnerable and know how to recognize the symptoms of heat-related illness can help save lives. We additionally need to have arrangements set up if there should be an occurrence of blackouts — when we can’t depend on cooling systems, for example. At last, we should not fail to remember creatures and pets, as they will require security during these times as well,” finishes up Cvijanovic.

ISGlobal makes a heat index calculator.

In addition to the paper that was published in Nature Climate and Atmospheric Science, an ISGlobal team made a heat index calculator. The straightforward instrument calculates the heat index and offers suggestions for how to remain safe in hazardous conditions, in addition to guidance on the level of risk. To work the adding machine, clients simply have to present temperature and relative stickiness values, the two of which are given by a larger number of people of the homegrown thermometer models on the lookout, and that way they can get an assessment of the circumstances in any of the rooms of their homes.

Even though there are other online heat index calculators, this is the first one to use the corrected and extended heat index that the researchers at UC Berkeley recently developed. The instrument is planned to give appraisals of indoor gambling.

“We need to get used to incorporating tools like this heat index calculator in the same way that we consult forecasts on a daily basis—especially whenever there is a forecast for an extreme weather event—in order to learn to live with sustained dangerous levels of heat like we have never had before. According to Pau Rubio, Communication Coordinator at ISGlobal and a member of the team that developed the calculator, “a fundamental part of this is to improve communication and raise awareness of the importance of factors such as relative humidity in gauging risk.”

More information: Ivana Cvijanovic, Malcolm N. Mistry, James D. Begg, Antonio Gasparrini, Xavier Rodó. Importance of humidity for characterization and communication of dangerous heatwave conditions. npj Climate and Atmospheric Science, 2023. DOI: 10.1038/s41612-023-00346-x

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