Problems related to prolonged exposure to extreme heat, such as what has been occurring in Brazil in recent days, can cause serious damage to health. Some existing conditions may be aggravated, but others are triggered by high temperatures. The dangers are even greater for children, the elderly and people with poor health.
The strong sun can cause so-called thermal stress, to which the human body reacts, trying to balance its internal temperature, which is 36°C. Among other reactions, it releases sweat and presents vasodilation in the arteries, responsible for carrying blood to the organs. At these times, there may be a drop in blood pressure, causing a feeling of malaise, weakness and tiredness.
“There are several conditions that are aggravated by increased environmental temperature. Some are aggravated, but not generated by it, as in patients who already have a basic disease, such as rosacea. In this case, the skin worsens due to vasodilation caused by heat “, explains dermatologist Valéria Zanela Franzon, from the Brazilian Society of Dermatology.
However, there are other conditions directly related to heat, such as hives, red bumps called hives, which cause a lot of itching and discomfort. “They can be triggered in very hot environments and days, but also with baths at high temperatures, or even due to thermal stress”, she says.
The problems worsen at the beginning of summer, when people tend to expose themselves to the sun after months of cold weather and little light. Among the possible outcomes is polymorphous light eruption. “She spent the winter period, in which she protected herself, and then she puts on her bikini and goes for her first swim in the pool or beach”, says the doctor. The rash manifests itself in several red dots, especially on the neck and chest, causing a lot of itching.
Another common case on very sunny days is heatstroke, when the skin receives so much heat that it ends up burning. “I was at a party and I didn’t realize that the sun was between the clouds, so I didn’t feel burning. When I got home I noticed. Even the cold water bath burned me. It was horrible”, says student Luastel das Neves. She says that for the next three days she had a high fever and felt like she had the flu. Then, she saw the whole body peeling off. “Even my face, my hair peeled off. I couldn’t even put on clothes. It took about ten days for me to get better.”
Pediatrician Renato Kfouri explains that heatstroke is hyperthermia, when the skin’s cooling mechanism, sweating, fails and causes dehydration. “It can lead to low cerebral oxygenation, with serious neurological conditions.”
The dangers of the sun can be even greater in the elderly, as their skin is naturally more fragile and dry, in addition to changes in circulation. “They suffer more in the heat and need extra care”, says cardiologist Fernando Nobre, from the USP Faculty of Medicine.
“This does not mean that young people are free from danger. No one should be exposed to extreme temperatures for a long time, even if protected”, he warns.
Babies suffer in another way, with dehydration and excess clothing. “Parents end up overdressing the child, who may not be able to get his body to exchange heat with the environment. As a result, he sweats too much and ends up developing miliaria, known as prickly heat,” says Franzon.
There are several types of prickly heat, but the most common is white, with a liquid inside, called vesicles. “It is necessary to leave the child in light clothing, so that the body can ventilate and the sweat gland works properly”, adds the dermatologist.
Low relative humidity also increases the risk of respiratory diseases. Dryness of the airways favors thicker secretion from the airways and facilitates viral and bacterial infections, as well as respiratory infections. “Hydration works as a fluidizer of these secretions”, highlights Kfouri. “As a result, we have greater exposure to allergens, causing allergic diseases such as rhinitis, asthma and bronchitis.”
The recommendation is not to expose yourself to sunny outdoor environments, especially between 10am and 4pm. “External physical activity is absolutely contraindicated. Even healthy people should avoid it. This applies to young people and children in schools”, says the cardiologist.
Water is essential to avoid dehydration. “Drink water at all times, not just when you feel thirsty. Wear sunscreen, a hat, glasses, a cap and an umbrella”, reinforces Nobre, highlighting that this is not the time to want to get tanned for the summer.