Extreme Heat and Pollution May Double Fatal Heart Attack Risk

Exposure to a combination of extreme heat and fine particulate pollution may double the risk of death from a heart attack, a study finds.

Women and adults over the age of 80 may be the most vulnerable to exposure to high temperatures and air pollution.

The study that appeared in the journal Circulation analyzed 202,678 heart attack deaths between 2015 to 2020 that occurred in the Chinese province of Jiangsu, a region with four distinct seasons and a wide range of temperatures and fine particulate pollution levels.

The average age of adults who died of heart attacks was 77.6 years, with more than half of them (52%) being over 80.

The analysis included the daily heat index, capturing the combined effect of heat and humidity, the length of heat and cold waves, and particulate exposure on the day of each death and one day before death. The pollution levels were considered high on any day, with an average level of fine particulate matter above 37.5 micrograms per cubic meter (ug/m³).

The study found that the risk of heart attack was 18% higher during ­two-day heat waves with temperatures ranging from 82.6 to 97.9°F. As the risk increases with rising temperature and duration, four-day waves with the heat of 94.8 to 109.4°F were associated with a 74% higher risk of heart attack.

During the four-day heat waves with fine particulate pollution above 37.5 ug/m³, the fatal heart attack risk doubled.

While two-day cold snaps with temperatures ranging from 33.3 to 40.5°F increased the risk for heart attack by 4%, cold days with high levels of fine particulate pollution did not have an equivalent increase in the risk of heart attack death as heat waves.

The researchers estimated that up to 2.8% of heart attack deaths may be attributed to the combination of extreme temperatures and high levels of fine particulate pollution.

Fine particulates are less than 2.5 microns in size and may be inhaled deep into the lungs. They are primarily associated with fuel combustion, such as particles from car exhaust, factory emissions, or wildfires. Previous research has linked fine particulate pollution with heart disease, stroke, dementia, cancer, and other health conditions.

As the planet has entered the era of global boiling, according to the World Health Organization, increasing evidence shows that extreme temperatures have multiple effects on our health. They are known to exacerbate allergies and asthma, pest-related illnesses like Lyme disease, injuries, and premature death, among others.

A recent study found that extreme heat costs the United States healthcare system more than $1 billion per year, as it leads to additional ambulatory care, emergency department, and heat-related hospital visits.

And because global temperatures are set to reach new records in the next four years, we may see more heat-related deaths.