Heat waves are emerging as one of the most significant environmental threats to the population of Brazil. A recent study conducted by researchers from the Oswaldo Cruz Foundation (Fiocruz) and the Federal University of Bahia (UFBA) estimated that nearly 120,000 deaths recorded between 2000 and 2019 were associated with episodes of extreme temperatures.
The research covered 5,566 Brazilian municipalities, practically the entire country, and allowed observation of how the sustained increase in temperatures affects various health indicators. The results show that extreme heat was related to 0.6% of the total mortality recorded during that period, excluding accidents and acts of violence.
Additionally, specialists identified a significant increase in hospitalizations due to respiratory, renal, and gastrointestinal diseases during intense heat events. Thus, the study provides a comprehensive view of the effects that climate change is already having on human health.
The most vulnerable groups to rising temperatures
The analyses revealed that the impacts do not affect the entire population in the same way. Older adults, people with pre-existing respiratory diseases, women, and those with lower levels of education showed a greater vulnerability to heat waves.
Furthermore, among those over 60 years old, there was a particularly high sensitivity to respiratory, renal, and metabolic diseases, including diabetes. In many cases, cardiovascular conditions associated with extreme temperatures can rapidly worsen and lead to fatal consequences before requiring hospital care.
On the other hand, the research detected significant social inequalities. People with less access to resources, adequate infrastructure, and health services recorded a higher relative risk of mortality, highlighting how the climate crisis amplifies pre-existing issues.
Increasing hospitalizations and effects on children
The study also allowed for the identification of specific patterns according to age. Among children under ten years old, gastroenteritis appeared as one of the main causes of hospitalization associated with extreme heat.
This situation is related to a higher predisposition to dehydration and environmental changes that can affect water quality and food preservation. As a result, episodes of high temperatures pose additional risks to child health.
Meanwhile, in virtually all regions of Brazil, hospitalizations for pneumonia, kidney failure, and other genitourinary diseases increased during heat waves. These findings reinforce the need to strengthen health systems in the face of increasingly demanding climate scenarios.
How heat waves affect health
Heat waves cause a series of physiological alterations that can severely compromise the body’s functioning. When temperatures remain elevated for several consecutive days, the body finds it more difficult to regulate its internal temperature.
As a result, the risk of dehydration, heat exhaustion, and heat strokes increases, conditions that can affect vital organs such as the heart, kidneys, and brain. Additionally, high temperatures increase cardiovascular demand and worsen pre-existing chronic diseases.
On the other hand, extreme heat can deteriorate air quality by promoting the formation of tropospheric ozone and other pollutants. This leads to greater respiratory complications, especially in children, older adults, and people with lung conditions.
An environmental challenge that demands urgent adaptation
Researchers observed that the frequency and intensity of heat waves increased in most Brazilian municipalities between 2000 and 2019. The most persistent events were recorded in the North and Midwest regions, while the most intense thermal anomalies appeared in the South and Southeast.
In this scenario, specialists propose to strengthen climate monitoring systems, expand early warnings and improve the integration between meteorological information and health surveillance.
They also highlight the importance of promoting greener, more resilient, and climate-adapted cities. The expansion of tree-covered areas, the reduction of impermeable surfaces, and better urban planning appear as key tools to reduce the risks associated with extreme heat and protect the most vulnerable communities.
