In recent months, hot flashes affected several countries, including Brazil. With the arrival of El Niño and atmospheric blockages, doubts arise about the impact of heat on the human body and its possible health hazards.
Heat can be fatal in many ways, mainly due to humidity and hydration issues. The risks vary in dry and humid climates, but the essential thing is to maintain basic care such as good hydration and protection against the sun, especially for the elderly, children and people with chronic illnesses.
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As mammals, we have an internal temperature regulation mechanism, which maintains, on average, 36.5 ºC. At high temperatures, our body reacts to cool itself, with sweating being the first response.
Sweating leads to fluid loss. If this water is not replaced, dehydration occurs. This reduces blood volume, affects blood pressure and makes the blood thicker, increasing the risk of clotting.
To dissipate heat, the heart pumps faster. This can be dangerous for those with heart problems, increasing the risk of heart attack, arrhythmias, strokes and blocked veins.
Excess sweat alters the amount of electrolytes, affecting muscle and nerve functions. This can lead to seizures, heart spasms and breathing difficulties.
In severe cases of dehydration, the body conserves water, reducing sweating. If sweating stops or the weather is very hot and humid, body temperature can increase, causing possible damage to organs and nerve cells.
Vulnerable groups include marginalized communities, who often have less access to air conditioning and work in more intense conditions.
Sweating is effective because it allows blood to reach the surface of the body and dissipate heat. In dry weather, sweat evaporation occurs easily, but in high humidity, the process becomes more difficult. This is known as “wet bulb temperature”.
In low humidity conditions, the body can tolerate heat as long as water is available to drink. In high humidity, wet bulb temperatures above 35 ºC become difficult to withstand without the aid of air conditioning or ice water.
Studies show that heat is not just a theoretical risk. A survey by “Nature” magazine, carried out in 2022, revealed that extreme temperatures (including cold) caused around 6% of deaths in Latin America.
The study analyzed the relationship between temperatures and mortality in 326 cities in nine Latin American countries, including more than 15 million deaths.
It was found that, in the heat, each additional degree Celsius resulted in a 5.7% increase in deaths, mainly from cardiovascular and respiratory diseases, especially affecting children and the elderly. In contrast, respiratory infections were more influenced by excessive cold.
