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Heat Waves Rolling In

Photo credit: Steve Marcus/Las Vegas Sun via AP

By Leila Waid.

The beginning of summer has already brought immense heat waves throughout the world. Countries in Southeast Asia, such as India and Thailand, already had extreme heat waves in April—with UNICEF stating that the extreme temperatures posed a risk to 243 million children. In the Southwest U.S., June has also seen record-breaking extreme temperatures in early June. With the summer just beginning, how many more heatwaves will the world endure this season, and how many individuals will be at risk?

Heat waves are a significant public health issue because of the variety of health issues they pose. They are a prescient environmental justice issue because, due to climate change, the temperatures will keep climbing to unbearable levels. A study using modeling techniques has found that heat waves will become more extreme and longer-lasting in the latter half of the 21st century. An alarming finding from another study forecasts that “the limit for survivability may be reached at the end of the twenty-first century in many regions of the world” because the combination of high heat and humidity levels (referred to as the wet-bulb temperature) can pose extreme danger to human health.   

One way that heat waves impact human health is by increasing the risk of cardiovascular disease. Heart disease is already the number one cause of death in the U.S. According to the American Health Association, close to 50% of the American population has some form of heart disease. This finding means that half of Americans are at an even more increased risk from heat waves. Along with impacting those who already have heart issues, heat waves are also associated with the development of heart disease – with epidemiological studies showcasing that increased temperatures can lead to the development of ischemic heart disease.

Increased temperature places undue stress on the body, and these changes can cause “imbalances in the autonomic control of the heart, increase local arterial pressures, induce systemic inflammation, and impair clotting responses.” Thus, heat waves place those with pre-existing heart disease in increased danger and also increase the risk of heart disease development in the rest of the population. One study modeled how climate change will impact cardiovascular rates in the future and found that death from heart disease could increase from 162% to 233%. Currently, extreme heat causes an estimated 1,651 deaths annually from heart disease. The study projects that this number could increase anywhere from 4,320 to 5,491 deaths by the mid-21st century.  

As with most aspects of health, the impacts are not felt equally across the populations due to societal factors. For example, those with lower socioeconomic status face worse health outcomes during heat waves. One study examined whether insurance status played a role in heat-induced heart attacks and found that it was a critical factor in individuals’ health outcomes. Based in New York, the study found that individuals without health insurance – a stand-in for socioeconomic status (SES) – had a higher risk of myocardial infarction (heart attacks) during extreme heat even than those with health insurance. Another study conducted in Hong Kong found similar results – older individuals with lower SES were more likely to be admitted to the hospital during heat waves than those with higher SES.

Climate change continues to cause record-breaking heat waves year after year, and thus, we need to be aware of all of the risks these temperatures pose to our health. At an individual level, it is essential to understand what factors can place you at risk and to avoid outside activity, if possible, during these extreme temperatures. At a community level, we must look out for one another. For example, this summer, check up on your elderly family members and neighbors and be aware of signs of heat exhaustion and heat strokes in others so that you can provide assistance in case of emergencies. And at a societal level, keep fighting for and supporting climate change policies!