Heat waves: 7% of hospitalizations in the SUS are due to temperature fluctuations

Climate change is the biggest concern in the area of ​​Health in the 21st century. The human body has a limit to withstanding high temperatures, which can suffer consequences such as stress, heart failure and acute kidney damage due to dehydration. According to the World Health Organization (WHO), a heat wave is directly related to an increase in deaths. High temperatures account for 7% of hospitalizations in the Unified Health System (SUS).

Raphael Coelho Figueredo, member of the Biodiversity, Pollution and Climate Committee of the Brazilian Association of Allergy and Immunology (ASBAI), explains that heat waves cause an increase in inflammatory mediators in the human body, mainly affecting the extremes of age, pregnant women , obese people and people with chronic diseases, worsening allergic diseases, particularly respiratory allergies, such as asthma and rhinitis, and skin allergies, such as atopic dermatitis.

“Unlike other extreme weather events, such as tornadoes and floods, heat makes people feel less aggressive or more tolerable. This is it false perception which makes heat waves extremely dangerous for human health”, explains Figueredo.

According to the expert, there is an increase in the risk of cardiovascular and respiratory mortality on days of heat waves compared to days when the temperature is milder. There is also a risk of causing significant thermal stress in all living organisms such as plants, affecting photosynthesis, respiration, growth, development and reproduction. It also affects animals, leading to physiological and behavioral changes, such as reduced caloric intake, increased water intake, and decreased reproduction and growth.

“Five physiological mechanisms can be triggered by high temperature: ischemia, cytotoxicity, inflammation, disseminated intravascular coagulation and rhabdomyolysis”, warns Figueredo.

Above 39°C, 40°C, enzymes fundamental to metabolism suffer an abrupt drop in the speed of chemical reactions necessary for life. The body begins to stop breaking down proteins and sugars for nutrients and energy.

The expert says that humans control their temperature in two ways. The first is through blood vessels that dilate to bring more blood to the skin so that heat can be radiated away from the body. The second is through sweat, which cools the skin through evaporation. Heat can seriously impact seven organs: brain, heart, intestines, liver, kidneys, lungs and pancreas.

The body also loses a lot of fluid in an attempt to relieve itself through sweat, which leads to dehydration and makes the blood viscous, affecting the kidneys and heart, which are more demanding. Dehydration also causes vasoconstriction, which increases the risk of thrombosis and stroke.

“Extreme heat plunges the body into chaos. Understanding the effects of extreme events on health is a central issue for the development of climate policies focused on the health of the population”, comments the ASBAI specialist.