A recent study has brought to light the lethal consequences of extreme heat on the heart and suggests that climate change may result in a surge of heat-related cardiovascular fatalities in the United States in the coming years. This risk is higher for vulnerable groups, including Black adults, seniors, and urban dwellers.
Extreme heat days, defined by the Federal Emergency Management Agency as “a period of two to three days of high humidity and temperatures exceeding 90 degrees,” are becoming increasingly frequent.
Between 2008 and 2019, the heat index, which factors in both temperature and humidity, exceeded 90 degrees on an average of 54 days each summer in the US.
During these scorching periods, there were nearly 1,700 excess cardiovascular deaths annually, as revealed in a study published in the Circulation journal.
The researchers predict that if global fossil fuel development continues to expand and minimal efforts are made to reduce planet-warming emissions, the US could experience 80 days of extreme heat each summer, resulting in over 5,491 excess heat-related cardiovascular fatalities annually.
Even with more proactive climate change mitigation measures, the US could still encounter 71 days of extreme heat each year, leading to a 2.6-fold increase in heat-related mortality. This scenario could result in over 4,320 excess cardiovascular deaths linked to excessive heat by the mid-century.
Dr. Lawrence Fine, a senior adviser at the National Institutes of Health’s National Heart, Lung, and Blood Institute, emphasized that while extreme heat currently contributes only a small fraction of total cardiovascular fatalities, it is crucial to mitigate this risk due to the increasing prevalence of hot days.
Heat-related deaths are often concentrated during heatwaves and impact individuals who are more vulnerable due to their health conditions or other factors, which can strain emergency rooms and the broader healthcare system.
The study’s projections are based on data from the United Nations’ Intergovernmental Panel on Climate Change, incorporating population growth, migration trends, and greenhouse gas emissions. The analysis extends to the years 2036 through 2065 and uses county-level data for the contiguous 48 states in the US.
The summer of 2023 has offered a stark illustration of the dangers of extreme heat, with Maricopa County, Arizona, reporting a significant number of deaths due to heat-associated illnesses. This year marked the deadliest for heat-related fatalities since the county began tracking them in 2006, largely due to record-breaking temperatures and prolonged periods of extreme heat in the Southwest.
The human heart is particularly vulnerable to the effects of extreme heat. When the body overheats, the heart has to work harder to maintain a stable temperature, which poses a significant risk to individuals with pre-existing cardiovascular conditions. Prolonged exposure to heat can lead to increased inflammation and blood clotting, elevating the risk of heart attacks and strokes.
The study also underscores the disproportionate impact of extreme heat on Black adults, who may face a six-fold increase in heat-related cardiovascular deaths in the coming decades compared to a projected 2.4 times increase among White adults. Seniors over the age of 65 and individuals living in metropolitan areas are also expected to be disproportionately affected. Demographic changes, including an aging population and urban expansion, may exacerbate these vulnerabilities.
Efforts to address heat-related fatalities should be targeted at protecting those who are most at risk, including strategies such as providing access to cooler environments, increasing tree cover, and ensuring better healthcare access.
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