Heat waves are one of the leading causes of weather-induced mortality.
Heat waves and extreme temperature alerts have become commonplace in many countries, but rarely do these alerts include other factors that dangerously affect human beings and hinder their ability to adapt.
Advisories from weather services about heat waves should be based not only on temperatures, but include heat stress indices that take into account factors such as humidity, wind and sun exposure, according to a recently published scientific study.
A high level of humidity in the environment and the absence of wind can make, for example, that an extreme temperature of 37ºC is more harmful to health than the same temperature in a dry environment by making it difficult for the human body to cool down.
This is one of the main points of the study prepared by an international scientific team from the Barcelona Institute for Global Health (ISGlobal) and the London School of Hygiene and Tropical Medicine (Lshtm) published in the journal Npj | Climate and Atmospheric Science de Nature.
In the study, they warn that relying solely on temperatures may be insufficient to inform the population about the true health risks of a heat wave, and they request that this data be included in the alerts.
What is heat stress
The Spanish scientist and head of ISGlobal’s “Climate and Health” program highlights that “more than anything else, what the study does is emphasize that communication by meteorology services and how extremes, waves of heat, is based solely, at least here in our country and in other countries, on maximum temperatures.
However, he believes that the footsteps of other countries such as the US, Canada and Germany should be followed, which have already included heat stress indices when reporting heat waves “as a more appropriate measure of the danger of a situation.” alert, basically because at the same temperature, at different humidity, the risk is different.
With humidity above 50% and high temperatures, the body loses the ability to dissipate excess heat by not being able to sweat the same, so it cannot cool down, which can pose harmful health risks.
Although each person’s threshold for heat resistance varies depending on a number of individual factors, different indices of heat stress have been designed to describe the impact of weather conditions on the body, including the point at which the conditions experienced can become a threat to human health.
Just as there is no single heat alert level for everyone, there is also no single heat stress index.
Some of the best known examples are humidex (Hu) -used in Canada, the heat index (HI) -used in the US, and the universal thermal climate index (UTCI), used in Germany.
However, the actual message of heat wave danger through the news and media continues to be mostly linked to maximum temperatures and rarely includes information on the expected values of these indices, also partly due to public ignorance.