Findings from the Intermountain research were presented in a pair of studies at the American Heart Association’s Scientific Sessions 2023, which is being held in Philadelphia.
In the first study, researchers from Intermountain examined the association between fine particulate matter (PM2.5) and ozone air pollution, and hospitalizations for unstable angina (unstable chest pain that does not result in organ damage) and acute myocardial infarction (heart attack in which part of the muscle dies) during two distinct seasons in Utah when these types of pollution is at higher levels.
Seasonal Impact: Investigating Patient Health Amidst Summer Wildfires and Winter Inversions
Researchers studied patients during summer wildfire season (June to October), and during the winter inversion season (November to March), when cold air is trapped by surrounding mountain ranges. Temperatures rise during an inversion along with elevation, which keeps pollutants like those from vehicles and industry in that cold, lower layer, but inversions don’t happen in the summer. Short-term PM2.5 elevations in summer come from wildfire smoke and usually that smoke is generated in places like California or Oregon that are 700 or more miles away.
For the study, researchers surveyed the health records of 21,414 people treated for heart attack or unstable chest pain between 1999 and 2022 at 11 hospitals throughout Utah’s Wasatch Front region.
They also found that risk of unstable chest pain increased during both seasons, but that people waited up to two weeks to seek treatment for it during the winter. The research team found no association between hospitalization rates and ozone pollution levels.
In the second study, researchers looked at the association between PM2.5 and ozone, and hospitalization of patients with atrial fibrillation. To do so, they surveyed the electronic heath records of 347,157 people with a previous atrial fibrillation diagnosis who were hospitalized for any reason; 25,601 hospitalized specifically for atrial fibrillation, and 77,893 given a first-time atrial fibrillation diagnosis between 1999 and 2022 at the same 11 hospitals.
PM2.5-Linked All-Cause Hospitalizations in Pre-diagnosed Atrial Fibrillation Patients
They found that short-term increases in PM2.5 led to higher all-cause hospitalization in patients already diagnosed with atrial fibrillation, but no increase in first-time atrial fibrillation diagnosis.
Researchers found hospitalization primarily for atrial fibrillation was also higher during the summer wildfire season (about 9% to 10% increase for each day of high PM2.5 levels, and only 3% in winter). The research team found no association between hospitalization rates and ozone pollution levels.
These findings suggest that “atrial fibrillation is being triggered by air pollution, but it’s something else that’s making them go to the hospital,” said Horne.
“It could be that when air pollutants are inhaled, it causes inflammation in your lungs or your circulation or heart, and changes the way your body’s functioning,” he added.
The differences in people coming into the hospital during the summer and winter could also be behavioral, Dr. Horne noted, that their perception of risk may be different in the summer, and also that Utah’s population tends to swell in the warmer months due to tourism.
“The bottom line is that if someone is thinking maybe they should go to the hospital or maybe they shouldn’t, they should fall on the side of caution and get themselves evaluated,” Dr. Horne said.