As this summer breaks temperature records around the world, pollution appears to compound the dangers of extreme heat. A study published on July 24 in the journal Circulation found that exposure to severe heat coupled with high pollution levels was linked with double the risk of a fatal heart attack. The study found that extreme cold, too, along with high pollution, was associated with the same risk.
The study analyzed over 202,000 deaths by heart attack between 2015 and 2020 in China’s Jiangsu province. The researchers found that extreme temperature fluctuations coupled with high levels of particulate matter (PM), the microscopic substances floating through the air and likely our airways and bloodstream, seem to combine to pose a higher risk for deadly heart attacks. The team estimated that of all these heart attack deaths, 2.8 percent could be attributed to extreme temperature events and PM2.5.
PM2.5, or particulate matter 2.5 micrometers and smaller, are particularly dangerous because they’re fine, difficult to remove, and easy to absorb. These are the solid and liquid droplets floating through the air from pollution. Long-term exposure to PM2.5 can lead to cancer, stroke, heart attack, respiratory problems, and inflammation. Demographically, older adults and women appeared to be “especially” at risk, according to the paper.
They found that the threshold for twice the risk of a deadly heart attack appeared when pollution exceeded 37.5 micrograms per cubic meter and a heat wave persisted for four days.
Additionally, the researchers looked at how “extreme temperature events” — which they defined as anything in the range of 82.6 to 97.9 degrees Fahrenheit — alone contributed to health. They found that two days in that temperature range increased the risk of death by heart attack by 18 percent. Four days of heat between 94.8 and 109.4 degrees Fahrenheit increased that risk by 74 percent.
“Extreme temperature events are becoming more frequent, longer and more intense, and their adverse health effects have drawn growing concern,” senior author Yuewei Liu, professor of epidemiology in the School of Public Health at Sun Yat-sen University in Guangzhou, told CNN.
