Rising Global Temperatures Result in Increased Heatstroke and Respiratory Problems
June marked the 13th consecutive month of record global temperatures, according to data from the European observatory Copernicus. According to the observatory, the following month, on July 22, 2024, the world recorded the hottest day in history, with an average of 17.16 degrees, including countries in winter. The average surpassed the previous records of 17.09°C, on the previous day, July 21, and 17.08°C, recorded just over a year ago, on July 6, 2023. The database considers records since 1940.
An analysis of the years with the highest annual global maximum daily temperatures shows that both 2023 and 2024 recorded substantially higher annual maximums than those recorded in previous years. Another sign of the global warming trend is the fact that the ten years with the highest temperatures are the last ones, from 2015 to 2024. This increase in temperatures is a warning sign for scientists, environmentalists and the general population, who are already beginning to feel the effects of the heat on their health.
Heat and diseases
Neurosurgeon Fabio Godinho, from the Hospital das Clínicas of the University of São Paulo School of Medicine, explains that the increase in heat affects health in several ways, both directly and indirectly. “The increase in temperature is associated with a series of diseases whose frequency is increasing, not only in Brazil, but in other countries that are also suffering more directly from the heat. Among these diseases, we have infectious diseases, usually those transmitted by vectors such as mosquitoes. Malaria, dengue fever and chikungunya are examples of these diseases that are affecting more people. An increase in neurological diseases, such as stroke, has also been observed,” explains the specialist.
The study Climate change, thermal anomalies and the recent progression of dengue in Brazil , published in Nature’s Scientific Reports portal , indicates that, among other factors, heat waves were responsible for the expansion of dengue. If, before, there were five days of heat anomalies, now there are 20 days or more above average throughout the summer, which triggers the virus transmission process. The research mapped data between 2000 and 2021 and observed that the occurrence of extreme weather events and environmental degradation were decisive factors for the expansion of dengue.
Heat also has direct implications for the human body. “Temperatures above 40°C can lead to general symptoms of discomfort, asthenia and a drop in blood pressure. This all happens because the body’s system begins to need to cool down. As a result, the nervous system begins to dilate the peripheral blood vessels, especially those in the skin, which increases blood flow to the skin to help lose heat. This increase in blood flow to the skin causes a drop in blood pressure, which is very dangerous, especially for the elderly. Another symptom is excessive sweating, which causes dehydration, which can impair the functioning of the organs. Dehydrated blood becomes very thick and begins to have difficulty flowing through the body, reducing blood flow to the organs, including the brain and heart. This poses a serious risk in terms of the possibility of cases such as stroke or myocardial infarction,” he explains.
Heat tolerance
In addition to the increase in average temperatures, days with extreme temperatures have become frequent in several cities in Brazil. According to the National Institute of Meteorology (Inmet), 43 Brazilian cities had their thermometers above 40°C on the same day in November 2023, with a thermal sensation exceeding 50°C. “In dry places, humans can tolerate temperatures around 50°C, and that is to say, they can withstand short periods of time in these temperature regimes. However, for more humid places, 40°C is already a complicated situation, almost at the limit. This also depends on how acclimatized the individual is to those conditions. We Brazilians are quite tolerant to heat, as we are used to it. However, prolonged periods in regimes of 40°C or more are difficult to bear,” he warns.
The doctor emphasizes that there are groups of people who need more attention in this scenario. “The elderly and children certainly feel these issues more, as they are more susceptible to dehydration and other physiological changes. In a study recently published in the journal Neurology , it was observed that heat has increased the number of cases of cerebrovascular diseases, and the elderly are more vulnerable to this. The social development index is also an important factor, as people who live in poorer regions have fewer structures to withstand the heat, both in terms of thermal insulation and medical care. This is evident in the data. In more developed countries, cases of stroke due to inadequate temperatures are concentrated in the elderly, while in less developed countries, other age groups are affected. Finally, attention is needed for people with other associated diseases. Chronic diseases such as lung, cardiovascular and kidney diseases end up making the person more vulnerable as well”, he concludes.