Wasatch Front air pollution triggers more heart attacks in winter, more unstable chest pain in summer, study finds

The Intermountain Health study researched heart patients between 1999 and 2022.

(Francisco Kjolseth | The Salt Lake Tribune) Winter inversion conditions settle into the Salt Lake valley, obscuring the landscape on Monday, Dec. 7, 2020.

Utahns know that breathing in air pollution isn’t healthy.

But Intermountain Health wanted to know how air pollution during different times of the year affects heart patients.

Heart researchers at Intermountain studied more than 22,000 Wasatch Front patients from 1999 to 2022, and compared rates of heart attack and unstable chest pain — a predecessor to a heart attack — during both winter and summer spikes in PM2.5 pollution.

The findings: Bad air triggers more such cardiac events — but the risk, and type of cardiac event, varies by season.

Winter air pollution was associated with a significant increase in patients seeking same-day care for heart attacks, but not unstable chest pain. Patients experiencing unstable chest pain during winter inversion often waited weeks before seeking treatment.

In the summer, when wildfire smoke elevated PM2.5 levels, researchers found more people seeking same-day care for unstable chest pain.

“If it’s not sudden, crushing chest pain, like a heart attack... people might sit at home and think, ‘Well, it’s cold and snowing outside. Maybe I don’t want to go to the hospital,’” said Dr. Benjamin Horne, Intermountain Health’s director of cardiovascular and genetic epidemiology, and the lead author of the study.

“But in the summertime, for whatever reason, which we don’t understand yet, they are going immediately because of that chest pain,” Horne said, “even though it’s it’s not an actual heart attack yet.”

These findings are revelatory, Horne said, but they also beg more questions.

For instance, he said, It’s not clear if winter inversion has more dire impacts on people’s health than wildfire-caused summer air pollution. It’s also unclear why people wait longer to go to the hospital for the same pain that causes patients in the summer to seek same-day care.

Regardless, Horne said, people should be “judicious” about recreating outdoors when the air is bad in either season. Also, he said, those taking medications for blood pressure, Type 2 diabetes or cholesterol should be sure to take their medicine during bad air days to help reduce their risk of a heart attack or unstable chest pain.

“If you’re having symptoms, if you have chest pain, when you exercise, you should get that checked out. Especially if you have chest pain when you are sitting and not doing anything,” Horne said. “That’s something that you should go and see your doctor about.”

No matter what season it is.