How hot is too hot for people?

how hot very hot, too hot? This is a very pertinent question now that we keep breaking temperature records due to changing of the climate. If we do nothing to fix this, the situation will only get worse, and there may come a time when spending time outdoors will be really dangerous. Now where is this point? This is a question of great interest Lewis Halseyprofessor and researcher Roehampton University, in the United Kingdom. He and his team have spent years trying to find the answer, and although it’s not easy to come up with a specific number, it seems like it’s out there somewhere. from 40ºC to 50ºC.

It all depends on many factors, such as gender, age or activity of each person. However, when the 40-degree barrier is exceeded, the situation becomes dangerous, since basal metabolic rate. This is a phenomenon that refers to the energy that is expended per unit time at rest. Ideally, keep it as low as possible. In the case of humans, temperatures below 40ºC remain very stable, but when this barrier is overcome starts to grow rapidlyespecially when the humidity is also high.

This is where the risks begin to show up. For this reason, the investigation Halseywhich has just been presented at a conference on the occasion Centenary of the Society for Experimental BiologyThis is something very necessary. And it’s that way, we can know when it’s getting too hot and take action accordingly.

Why is it dangerous to increase basal metabolism?

People endothermic animals. This means that we maintain a constant body temperature, independent of the ambient temperature. In our case, this around 36.5ºC. It doesn’t matter if it’s 10ºC or 39ºC outside. We always have about the same temperature.

This is achieved through mechanisms such as sweatingwhich is nothing more than the release of a liquid that, once on the surface of the skin, evaporates, taking away heat from the body.

All this also allows us to keep our metabolic rate stable and low, expending as little energy as possible when we are at rest. Unfortunately, everything has a limit. It has been studied in many animals that when a certain temperature is exceeded, the metabolic rate increases dramatically, with consequences that affect their health. Interestingly, there are animals in which it has been studied much more than in humans. For this reason, Halsey conducted a study in 2021 aimed at calculating when it is too hot for our species.

Danger of being too hot

During the 2021 study, Halsey and her team ran a one-hour series of volunteers through four different scenarios. In the first, the temperature was 40ºC, 25% humidity. After that, the temperature was maintained, but the humidity increased to fifty%. Finally, the temperature rose to 50ºCagain with moisture. 25% or 50%.

Thus, it was observed that even under the mildest conditions, at 40ºC and 25% humidity, the participants’ resting metabolic rate increased by 35%. Then, at 50ºC and 50% humidity, it was increased by another 13%. This sudden increase in energy can be seen as a factory running at full capacity. Participant body temperature they also started to rise, demonstrating that conventional mechanisms such as sweating are no longer sufficient to maintain a constant temperature. 50ºC is too hot, but even at 40ºC already problems begin.

Our species is not adapted to such an increase in temperature, so at this moment it may serious health problems. Sweating will continue in an attempt to solve the problem of rising temperatures, so the first of these problems is dehydration. It will also increase peripheral blood flow to try and dissipate heat through the skin. This can cause problems such as arrhythmias, fainting or seizures. Then will come heatstroke and, if the situation is very serious, even death.

With all this, it should be quite clear that the temperatures that we usually see in summer are too high and can cause serious problems. This should be considered, especially for those who work outdoors. Heatstroke will become more and more common, and if the population is not properly warned, there may be many regrettable deaths. These investigations will henceforth be more and more necessary. Unfortunately, this is something we have to take very seriously.