The heat wave season raises awareness about the effects of high temperatures on the body. According to Cristiane Zambolim, cardiologist at Hospital Alemão Oswaldo Cruz, the intense heat wave can cause symptoms associated with dehydration and a drop in blood pressure.
Among the main symptoms and warning signs related to high temperatures are:
- Increased heart rate;
- Indisposition;
- Soft feeling;
- Dry mouth;
- Drowsiness;
- Drop in blood pressure;
- Fainting;
- In severe cases, convulsive crises and loss of consciousness.
When can heat kill?
Globally, in 2023, deaths related to extreme heat among people over 65 years of age increased by 167% compared to deaths in 1990. The data was released in a report published in October in the scientific journal The Lancet.
Despite this, another study published in December suggested that high temperatures are more harmful to young people than to the elderly. The research, published in Science Advances, indicates that 75% of heat-related deaths recorded in Mexico are occurring among people under the age of 35 — and a large proportion of them are between the ages of 18 and 35.
According to Zambolim, heat can lead to death depending on the person’s characteristics. “The extremes of age are more susceptible [aos riscos do calor]. So, when body temperature reaches 40 ºC, it can kill,” he says.
An increase in body temperature above healthy limits is called hyperthermia. The condition is related to factors such as high temperatures and air humidity. “When the temperature is hot and humid, it is more difficult for heat exchange between the body and the environment to occur. So, the person is unable, for example, to have the sweat reflex, which causes the body to cool its internal temperature”, explains the cardiologist.
“Heat can kill when a person is at a very high external temperature and doing, for example, physical activities; when there is not correct hydration; when it demands more from the body than it can achieve to maintain homeostasis, which is this heat exchange [entre o externo e o interno] to maintain his internal temperature at up to 37.5 ºC”, he adds.