Record heat waves are sweeping through various regions of the world as summer arrives, particularly in the northern hemisphere. This situation indicates that climate change may lead to temperatures rising to new record levels, potentially surpassing those recorded last summer and making it the hottest in 2000 years. It is suspected that the record temperatures already recorded in recent days have resulted in the deaths of hundreds, if not thousands, across Asia and Europe. As heat-related deaths rise, scientists state that the high temperatures negatively impact multiple organs, stressing the heart, damaging the skin, causing rapid dehydration, and ultimately leading to death if the body fails to cool itself quickly enough.
**The Brain**
As temperatures rise, the brain may struggle to process information, and this decrease in cognitive function can impair judgment, putting individuals at risk of falls or injuries. In extreme cases, high heat can cause serious inflammation in the brain. During phases of extreme heat, the nervous system does not function properly because the brain receives very little blood. Research indicates that heat also affects mental health. Increased temperatures have been associated with higher suicide rates in the United States and Mexico, while a study in Bangladesh found links between various climate-related stressors and anxiety and depression burdens. A study published in the Journal of the American Medical Association about two years ago showed that extreme heat days in the U.S. were associated with increased visits to emergency departments for mental health issues, including anxiety, self-harm, and substance abuse.
**The Skin**
Larry Kenney, a professor of physiology and kinesiology at Penn State University, states that when temperatures rise, the skin plays a crucial role in cooling the body as humans need to maintain their core body temperature within a "very narrow range." In a previous interview with CBC Canada, Kenney revealed that the two main ways we manage rising body temperature are by pumping a lot of blood to the skin and by sweating across most of the body’s surface and evaporating that sweat. However, this process can become compromised during extreme heat, especially when coupled with high humidity. These factors work together to disrupt sweat evaporation, rendering it ineffective for cooling the body while also leading to increased dehydration. Scientists refer to this condition as "wet bulb temperature," which is the point at which water stops evaporating. In such a case, when temperatures reach 35 degrees Celsius, the body becomes unable to cool itself, which can lead to imbalance and vital organ dysfunction, potentially resulting in death. Older adults and infants may be particularly at risk.
**The Heart**
As body temperature rises, stress on the entire cardiovascular system increases. According to experts, this occurs because more blood is retained in the skin while the body tries to cool itself. This situation puts more strain on the heart as it now has less blood to work with and must exert more effort to pump this blood to the rest of the body. Daniel Gagnon, a researcher at the Montreal Heart Institute, states that a lack of oxygen and nutrients for the heart can lead to life-threatening conditions such as heart attacks. Numerous studies show a correlation between extreme temperatures and cardiovascular issues. A study published in the journal *Circulation* indicated that the combination of extreme heat and air pollution increases the risk of fatal heart attacks by approximately 75%, particularly among older adults.
**The Lungs**
Inhaling hot, humid air can be challenging for the lungs, worsening respiratory distress in the elderly and children and exposing others to a higher risk of respiratory issues. An editorial in The Lancet medical journal in 2008 noted that extreme heat poses a particular danger to those with respiratory diseases, and the aggravation of chronic conditions such as chronic obstructive pulmonary disease and asthma significantly escalates with rising temperatures, often exacerbated by increased air pollution in urban areas and seasonal allergies. A study in the U.S. examined the impact of heat on the elderly and found that every increase of 5.6 degrees Celsius was associated with a 4% rise in emergency cases due to respiratory illnesses.
**The Kidneys**
When the body becomes dehydrated, it significantly affects the kidneys, which are the organs responsible for filtering blood by removing waste and excess water that is ultimately excreted as urine. Dehydration caused by excessive heat can lead to kidney failure, resulting in emergency hospitalization or death. The increased pressure on the heart, elevated body temperature, and fluid stress or dehydration can increase the strain on the kidneys. A previous study published in the journal of preventive medicine and public health reported a 30% rise in kidney disease incidence in high temperatures. Researchers also observed spikes in certain conditions, including kidney stones.
