The Wasatch Front experiences two distinct seasons of air pollution: in the summer, when wildfire smoke blows in from the west, and the winter, when inversions trap pollution in the valley. A new study from Intermountain examined how these two seasons affect heart health on Wasatch Front residents.
The study looked at 22,000 hospital visits for heart attacks or unstable chest pain at 11 hospitals across the Wasatch Front from 1999 to 2022, then compared them with spikes in fine particle pollution (PM2.5) during wildfire season and winter inversions.
“In the wintertime with the inversion, we get a substantial effect, and it's immediate,” said Dr. Benjamin Horne, a professor of research at Intermountain and lead author on the study. “Same day or the day after a rise in air pollution, we see an increase in hospitalizations for heart attacks.”
Horne says they found a 10% higher risk for each person each day they were exposed to an orange-level air quality index (AQI), which is “unhealthy for people in sensitive populations.”
Those who went into the hospital for heart attacks also tended to have an underlying coronary issue triggered by the inversion, rather than the inversion causing a heart attack in otherwise healthy people.
The study didn’t find a significant increase in heart attack hospitalizations in the summer. However, on the first day or two after a rise in PM2.5, there was a sudden increase of hospitalizations for unstable chest pain, which is recurring chest pain that occurs even when resting or doing low-impact activities.
The risk for same-day hospitalization due to unstable chest pain in wildfire season was 45% higher for each day a person was exposed to an orange-level AQI.
Those experiencing unstable chest pain in the winter, on the other hand, tended to wait up to two weeks before seeking treatment.
“There’s a combination here of the physiology that’s being affected by the air pollution and the behavior,” Horne said. “If it’s not sudden, crushing chest pain like a heart attack, where you just can’t breathe and the pain’s radiating down your arm and so forth, people might sit at home and think, 'Well, it’s cold and snowing outside. Maybe I don’t want to go to the hospital, the pain’s not too bad.'”
Horne said it’s still unclear if these seasonal differences are also caused by factors like a difference in pollutants, the magnitude of pollution or the distance from much of the wildfire smoke, which mainly comes from California and Oregon.
As inversion season approaches this winter, Horne encourages Wasatch Front residents to limit being outdoors when there’s an elevated AQI, especially those with a chronic disease.
"What I want people to do is think about, what am I doing on a day when the air pollution is elevated?” Horne said. “And can I reduce that risk for myself and for my family?”
