These dangerous conditions are caused by summer heat

By Alistair Gardiner
Published June 21, 2021

Key Takeaways

Summer is upon us, and heat waves are already descending on some parts of the country. These early summer scorchers are just a small taste of what’s to come, according to information published by the National Integrated Heat Health Information System, which illustrates a concerning trend: Unusually hot days and nights are becoming more and more common.

In the first decade of the 21st century, record high temperatures outnumbered record low temps by a ratio of 2:1.

While some look forward to a sweltering summer, the heat can raise health concerns for others. Findings from various studies have found that extreme heat events are becoming one of the leading causes of weather-related adverse health outcomes and deaths.

One review published in Health and Place found that heat wave events have a significant impact on ambulance and hospital loads in cities across the globe—including in the United States. In fact, one study in the review found a 10% increased risk of all-cause mortality in Seattle, WA, on days when heat waves were in effect.

Another review published in Geohealth found that there were roughly 12,000 heat-related deaths during the past decade. Using temperature data from the National Oceanographic and Atmospheric Administration and mortality data from the National Center for Health Statistics, the authors also provided an estimate for where that figure might go over the next century. 

By the year 2100, there could be roughly 97,000 Americans dying every decade from heat-related health complications, they found. 

As noted by the National Integrated Heat Health Information System, extreme heat can result in impairments in the body’s ability to regulate its temperature. This, in turn, can lead to a range of adverse health outcomes, from heat cramps to death. So, as climate change leads us to hotter summers and more frequent heat waves, here are the diseases and health conditions that should be on our radars, according to research.

Heat stroke and heat exhaustion

According to information provided by the CDC, there are several non-lethal heat-related illnesses that present with obvious symptoms.

These include largely benign conditions like heat cramps, where symptoms include muscle pain, excessive sweating, or sunburn characterized by painful red skin or blisters. In both cases, the CDC advises that you should seek shade and find ways to cool down. If your heat cramps last longer than 1 hour or if you have heart problems, medical help is in order. 

Heat can also lead to more serious conditions like heat stroke and heat exhaustion. Signs of the former include a body temperature of 103°F or higher; hot, red skin; a fast and strong pulse; headaches; dizziness; nausea; confusion; and loss of consciousness. If conditions worsen, the CDC advises calling 911 and cooling down by moving into a shady spot or placing cold cloths on the skin. The CDC also notes that you shouldn’t drink any water while awaiting medical help.

Heat exhaustion, on the other hand, presents with symptoms that include heavy sweating; cold, pale or clammy skin; a fast but weak pulse; nausea; muscle cramps; tiredness or dizziness; headaches; and fainting. If you’re experiencing these symptoms, move to a cooler spot, sip some water, and cool your body with wet cloths. If symptoms last longer than 1 hour or you begin vomiting, then it’s time to seek medical support. 

Chronic conditions and death

Heat-related conditions can get much worse than the generally benign ones listed above. This is illustrated in a report published by the CDC, which examined heat-related deaths that occurred in the US from 2004-2018. They found that exposure to heat can worsen certain chronic diseases or cause premature death in those with underlying conditions.

Using data from the National Vital Statistics System, researchers found that an average of 702 heat-related deaths happened annually over the study period, for a total of 10,527 deaths resulting from exposure to heat.

Among these heat-related deaths, 2,112 were a result of underlying cardiovascular diseases. Exposure to extreme temperature was found to be a contributing factor to 1,463 deaths from ischemic heart disease and 438 deaths from hypertension. The authors noted that some medications commonly used to treat these conditions, like beta-blockers, diuretics, and calcium-channel blockers, can interfere with thermoregulation and leave individuals less able to respond effectively to heat stress.

Beyond those with underlying conditions, at-risk populations include the elderly (people aged 65 years or older account for roughly 40% of all heat-related deaths), anyone engaging in strenuous physical activity outdoors, and those using alcohol or drugs like cocaine or methamphetamines.

A study published in Nature Climate Change found that hot temperatures are also associated with an increase in death by suicide. Researchers found that for each 1°C increase in temperature, suicide rates rise by 0.7% in the United States. Unmitigated climate change, researchers said, could result in up to 40,000 more suicides across the US and Mexico by 2050. 

Future research

Despite data illustrating an increase in the intensity and frequency of heat waves, there are still a number of under-researched areas that limit our understanding of how they affect health. According to the National Institute of Environmental Health Sciences, scientists and policy leaders have yet to develop a standard definition of heat-related health outcomes, explore the combined effects of exposure to heat waves and ambient air pollution on health, or focus on heat response plans. 

In the meantime, it’s probably best to pay attention to how you’re responding to the heat, seek shade if necessary, and ensure you’re drinking plenty of water. 

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