Cooling in hot weather: do popular methods work?

Summer is hot in the USA. Those who do not have air conditioning in their homes or offices will look for ways to cool down, often resorting to popular advice.

Edition with the BBC tried to look from a scientific point of view at the five very common people's councils suffering from the heat, to find out from the effectiveness.

1. Drink cold drinks and abstain from hot

Фото: Depositphotos

Drinking more in hot weather is the right thing to do. It is very important in such conditions to help your kidneys and prevent dehydration. But there has long been debate about what kind of liquid to drink - ice-cold or hot.

The theory behind the choice of the hot, is this: you heat yourself up from the inside, start to sweat more, which eventually cools you.

The human body is able to excrete up to two liters of sweat per hour, and this is a very effective way to lower its temperature.

But if the lost amount of fluid is not compensated for, you will soon become dehydrated - and because of this, some experts recommend avoiding hot drinks altogether in the heat.

In addition, they emphasize that it is better to avoid tea or coffee, because these drinks contain caffeine, increasing dehydration. However, very little evidence that a moderate amount of caffeine acts as a diuretic.

Indeed, some research supports the idea that cold drinks are better in hot weather.

Experiments were conducted, in particular, during which participants were subjected to severe physical exertion, and then their body temperature was measured as they were given either hot or cold drinks. It was found that the latter more effectively cool the body.

However, there is at least one possible problem with such studies - the method used to measure temperature.

Brave volunteers were given rectal thermometers. As noted by Olli Jay, a graduate student at the Department of Physiology of Thermal Control of the University of Ottawa (Canada), drunk cold liquid fell straight into the stomach, which is not very far from the supplied thermometer. It is not surprising, therefore, that the temperature quickly fell.

When a team of researchers led by Olli Jay took readings using eight thermometers placed in different parts of the body, it was found that hot drinks cool the body morebecause, as already noted, they increase perspiration.

So hot drinks in the heat help better. There is, however, a situation in which they are useless: if the humidity is very high or you are so dressed that sweat does not have the ability to evaporate. In this case, use cold drinks.

Verdict: This is a myth. Hot drinks will cool you down faster—unless the humidity is too high.

2. Use a fan

Фото: Depositphotos

The breeze from the rotating fan certainly brings relief. But we must take into account that the fan does not cool the air, it simply moves it, and the air flow it creates helps the normal heat exchange of our body - including the evaporation of sweat that appears on the skin from the heat.

Fans are used everywhere. There was even a casewhen three patients with heat stroke were cooled downwardly from the propeller of the light helicopter.

However, there are different opinions on the cooling efficiency of the fans.

In 2012, the authors Cochrane Analytical Reviews (which usually collect all existing primary research on a particular topic, and then evaluate them using strict rules to establish whether or not there is convincing evidence regarding a particular method or treatment) decided to test the effectiveness of the fans and with acute shortages of randomized controlled trials.

Most studies were observational, observant, without the intervention of scientists. Some of them found that the fans help, others noted that if the air temperature is very high, then the situation is only getting worse.

In general, it is believed that a fan can help if the air temperature is not higher than 35 degrees Celsius. If it is higher, then blowing the body with such air will only increase the thermal load and may lead to thermal shock.

So if the room is too hot, then the use of fans even accelerates dehydration.

In addition, fans are less effective at high humidity. In this case, though the air moves, it is filled with moisture, which makes it difficult to evaporate the sweat from human skin.

However, until randomized controlled studies are conducted, we cannot know for sure what effect the fans have.

And such studies are not easy to plan. Scientists will need to prepare everything for the moment when the next heat wave arrives - and the required temperatures may have to wait several years.

What we do know for sure is that ventilators are not always a salvation. Let's say during the heat of the year 1999 in Cincinnati 17 people died, and ten of them used fans, which were turned on when these people were found dead.

Of course, we don’t know—maybe without the ventilators they would have died even faster. Or maybe they only bought fans because they lived in very hot buildings.

Verdict: Need more data. But if the temperature has passed for plus 35 Celsius, it is better to turn off the fan.

3. Strong heat is dangerous only for older people.

Фото: Depositphotos

It is true that during especially hot days it gets to hospitals more people and many of them are elderly.

The body temperature at which our body feels most comfortable and functions normally is between 36 and 37,5 degrees Celsius.

Thermoreceptors on our skin, deep tissues and organs immediately detect an increase in temperature - even by one degree. If the ambient temperature is higher than our body temperature, we begin to sweat to cool ourselves down.

In addition, we release heat by sending more blood to our hands and feet (which is why they can be so hot at night).

Both of these methods of thermoregulation require more active work from our heart. Therefore, older people sometimes have heart attacks or heart attacks.

Unlike how a cold snap affects the health, the majority of deaths from heat occur already in the first days of its arrival.

Another problem with older people is that they are not always able to understand in time that they are overheating and their body is dehydrated.

However, all this does not mean that heat is dangerous only for the elderly. Children and people with chronic illnesses are also at risk, as is anyone who has mobility difficulties that prevent them from simply going to the window and opening it, fetching themselves water or brewing hot tea to replace the fluid lost from sweating.

When it is hot day and night, our body is very difficult to cool. Heat in Europe 2003 of the yearby some estimates, caused the death of at least 30 thousands of people, and some experts cite the number in 70 thousands. Of the 15 thousands who died in France, 1321 people were at the age not exceeding 64 of the year.

Verdict: Not true. Older people, of course, should be especially careful in the heat, but so do many others.

4. Need to open all windows

Opening a window is the first thing that comes to mind for most of us when it’s hot. But this can have the opposite effect.

It is necessary to open the windows only when the air outside is cooler than in the room (and this is how it usually happens at night).

During the heat of the day, you should keep your windows closed. Less sunlight gets into the room, so the temperature is not so high.

Even if you can create some airflow in your home or office by creating a draft, it will only work if the air is not too hot - otherwise you will not be able to cool down.

Moreover, if the content of pollen in the air is high, then such ventilation will only exacerbate allergies in those who suffer from it.

Verdict: This is not true if the air temperature outside the window is higher than in the room. But the windows open at night will make your life easier during the heat.

5. Need to drink beer

In the 1958 film A Hard Way to Alexandria, the character played by John Mills dreams of an ice-cold beer in the hot African desert sun. At the end of the film, after all the adventures and difficulties he has endured, he sits in a bar, they bring him the coveted beer, he takes a sip and utters the famous words: “Worth waiting for” (“It was worth waiting for”).

You don’t need to drive a truck through the desert in North Africa to have a beer at sunset. But will it help cool? Not always.

If it's only one glass, then the beer is unlikely to harm you. In various studies, researchers gave participants exercise to get them to sweat and then gave them beer, including non-alcoholic beer.

In one of 1985 research year such an experiment took place in an atmosphere of high humidity, and the “peak urination” occurred after drinking beer. This is not a good thing because it indicates that the body is losing rather than retaining fluid.

However, it should be emphasized that the difference in the results of those who drank non-alcoholic beer, and those who drank the usual, was extremely small.

Other, more recent research yielded similar results. Although regular water and refreshing drinks for athletes were more effective in compensating for fluid loss, beer also showed surprisingly good results.

Another study by Spanish scientists, in which participants spent 40 minutes on a running simulator, has shown: Both water and beer to the same extent helped to compensate for the loss of fluid.

And this is strange - because we know that people go to the toilet more often when they drink beer. Perhaps when the body becomes dehydrated and needs fluid, it leaves as much beer as it needs.

These are, however, small studies that didn't look at how body temperature behaved, so we can't say for sure whether beer cooled the body or how effectively.

But they demonstrated that one or perhaps two glasses of beer would replenish fluid loss rather than make it worse. So, perhaps the hero of the film "The Hard Way to Alexandria" was right, the pint of beer was worth the wait.

Verdict: It's true—at least when it comes to one or two glasses.

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