Study Finds Summer Environmental Risk Factors That Can Double Chances of a Heart Attack

Amidst this summer’s record-breaking heat waves and wildfires which have sent smoke pollution to neighboring countries, a new study has discovered that very combination can lead to an increased risk of heart attack.

The study was published on Tuesday in the American Heart Association’s Circulation journal. In order to obtain results, researchers studied 202,678 fatal heart attacks in China’s Jiangsu province from 2015-2020. Jiangsu experiences four distinct seasons, as well as a variety of temperatures, while seeing elevated air pollution during parts of the year.

Scientists focused on particles which shared a diameter of 2.5 micrometers (PM 2.5), roughly 30 times smaller than the width of a human hair. Much of the PM 2.5 pollution stems from combustion of oil, diesel fuel, gasoline, or wood. Wildfires, a common occurrence in recent years, are one of the primary causes of PM 2.5 pollution.

Researchers determined that twice as many Jiangsu residents died of heart attacks during four or more days of temperatures reaching 82.6–109.4 degrees Fahrenheit. Four consecutive days of temperatures reaching 95 degrees or higher raised the overall risk of heart attack by 74 percent.

It was also discovered that risk was enhanced by the presence of particulate matter, which are tiny particles of smoke, dust, or liquid in the air that are small enough to be ingested into the lungs or bloodstream.

The deceased patients measured were adults with an average age of 77.6 years. 52 percent were over the age of 80, while another 52 percent were male. Particulate exposure on the day of each death, as well as the previous day, were also included in the report. Overall, women were found to be more vulnerable than men.

Colder days were also shown to be associated with a higher risk of heart attack, though not to the same degree as hot ones. During a two-day period in which temperatures dipped between 33.3–40.5 degrees, risk increased by 4 percent. Meanwhile, three-day cold waves measuring 27–37.2 degrees saw a jump of 12 percent.

Higher particulate matter on the colder days did not have an effect on the causes of death.

The study’s senior author, Dr. Yuewei Liu, is an associate professor of epidemiology in the School of Public Health at Sun Yat-sen University in Guangzhou, China. In a statement announcing the results, Liu offered some helpful tips for avoiding both oppressive heat and airborne toxins.

“Using an air purifier in the house, wearing a mask outdoors, staying clear of busy highways when walking, and choosing less-strenuous outdoor activities may also help to reduce exposure to air pollution on days with high levels of fine particulate pollution,” he offered.

Liu also suggested that weather reports and officials could do more to alert the public to the threat of particulate matter on higher-temperature days.

“To improve public health, it is important to take fine particulate pollution into consideration when providing extreme temperature warnings to the public.”