Exposure to particulate matter pollution from wildfires could increase the risk of heart attacks and acute heart problems, according to a new study published in the Journal of American Heart Association Wednesday.

Australian researchers looked at data from wildfires in Victoria, Australia in 2006 and 2007, News Ledge reports. The team found that when surrounding areas were filled with smoke from the fires, there was a 7 percent increase in heart attacks.

Also, ischemic heart disease emergency visits increased more than 2 percent and ischemic heart disease hospitalization increased by 2 percent. The associations were observed in hospital admissions, out-of-hospital cardiac arrests and emergency department visits for ischemic heart disease after two days of wildfire smoke exposure, according to MedPage Today.

The association was mostly observed in patients 65 or older. Women showed a higher risk of IHD-related hospital admissions whereas men showed a greater risk for out-of-hospital cardiac arrests.

Lead author Anjali Haikerwal, who works with the Center for Occupational and Environmental Health at Monash University in Victoria, said that the particles in the wildfire smoke are “harmful because they are small and easily inhaled.” She added that the respiratory risks from inhaling the smoke–such as asthma–is already well-known, but the link to heart risks has been difficult to determine, Pioneer News reports.

The study’s results suggest that PM2.5 exposure from wildfire smoke may be “an important determinant of out-of-hospital cardiac arrests and IHD” hospital admissions, researchers said. They added that the elderly could be more susceptible to heart problems in wildfire situations.

Wildfire smoke is the largest source of PM2.5 air pollution. The authors said the “smoke from wildfires disperses widely and affects large portions of the population away from the fire source.”

Haikerwal warned that people should take precautionary measures during a fire. She added that the medical community needs to comprehend how large of an impact exposure to smoke can have.