Wildfire smoke is linked to more emergency room visits for heart attacks

More patients show up at Midwest emergency rooms with heart attacks when Canadian wildfire smoke coats the region with dirty air, new federal research showed.

Epidemiologists with the Centers for Disease Control and Prevention reported last month that there were 15 more ER-related heart attacks per day in the Midwest in summer 2023 when wildfire smoke was at its worst. The numerical increase was modest, but it was found in the northeastern U.S. as well and it builds the case for another health danger of smoky air. The research compared the ER usage during the wildfires with clean-air days in 2023 and summer 2022.

"We want people to really listen to the messages that are coming from their local area, their local health departments, in regards to when the wildfires are happening or there is poor air quality," said Essi Havor, a CDC epidemic intelligence service officer who led the research.

The heart attack link made practical sense to doctors in Minnesota, which this week experienced its first red alert air quality notice of 2024. Minnesota issued a record 21 red alerts in 2023 that were related to wildfire smoke and other pollutants, and many of those episodes drove patients who were wheezing or struggling to breath to seek medical attention.

Poor air quality can lead to inflammation inside blood vessels, which can cause plaques to break loose and cause heart attacks by obstructing blood flow to the heart, said Dr. Joe Browning, a HealthPartners general cardiologist. "Basically, when you're breathing in this type of air, that fine particulate matter can actually cross the vessels from the lungs and enter into your bloodstream."

The U.S. findings match pollution research in China that showed increased cardiovascular complications, in some cases within an hour of exposure, he said. Staying in climate-controlled indoor locations is the best prevention strategy, but people who go outdoors can protect themselves with the same high-filtration masks that reduce the risks of infection with the coronavirus that causes COVID-19, Browning said.

"I hate to start talking about N95 masks again, but they are useful in these sorts of situations," he said.

Dr. Kari Haley noticed an uptick in patients with breathing problems during her ER shift Sunday at Regions Hospital in St. Paul, probably because the inviting temperatures lured people outside when the air quality deteriorated. The wildfires in the summer months can be problematic because high humidity and heat on their own can increase stress on the body, she said. "The combination of them makes it that much worse, or that much more of a risk."

Havor said she wasn't surprised when her research showed higher rates of heart attacks from poor air quality among the elderly and people with underlying diseases. What was unexpected was the elevated rate among women as well. Follow-up research is needed to verify and explain that finding, she said.

"Something is going on that we need to understand," she said.

Hospital emergency rooms in the northeastern U.S. treated 357 more heart attack patients than expected on June 7-8, which were days of very unhealthy air quality, the CDC research showed.

Minnesota could soon have its own data resource to analyze the connection between poor air quality and health problems. A partnership among Minnesota's largest medical providers already offers trend data to show the prevalence rates of conditions such as asthma and heart failure. The group is currently cross-checking that data to see how extreme heat impacts illness rates and medical care in Minnesota, and it is planning to do the same with air quality data.

A poor-air quality day such as Monday could be compared with other recent Mondays to reveal its impact on hospital utilization and ER visits across the state, said Jesse Berman, a University of Minnesota assistant professor of environmental health sciences who is leading the analysis.

Minnesota at peak times of wildfire smoke last June had some of the worst air quality on the planet, causing even healthy people to get watery eyes and raspy breath. Berman said he suspects that convinced more people to observe the red alert warnings and protect themselves. While the high-risk groups are known, Berman said healthy people can be at risk if they go out on poor air-quality days and run long distances or overexert themselves.

"That smoke penetrates deep inside of their lungs," he said, "so they can be just as vulnerable as some of these people with pre-existing disease."