As wildfires continue to threaten communities across the U.S. — many of us are vulnerable to the effects of smoke.

While it may appear obvious that breathing heavy smoke from fires is bad for our lungs, less obvious is the threat to our heart health.

Researchers from the American Heart Association looked at data from 14 wildfire-affected counties in California between 2015 and 2017.

They found the risks of out-of-hospital cardiac arrests increased up to 70% on days following heavy smoke exposure from wildfires.

Wildfire smoke exposure is also linked to more emergency room visits for things like heart attacks, irregular heart rhythms, and heart failure exacerbation.

Experts ask people who aren’t in immediate danger from wildfires to get inside, shut the doors and windows and use air conditioners with high-efficiency air filters.

Avoiding exertion and staying hydrated is also important.

To learn more about recognizing the signs of a heart attack and performing basic life support including CPR in the event of a cardiac arrest visit the American Heart Association’s website.