Andrew Merry/Moment, Getty Images
(Andrew Merry/Moment, Getty Images)

The damage to homes, animal life and vegetation caused by wildfires is devastating – and they can wreak havoc on your health, too.

Inhaling smoke during recent California wildfires raised the risk of out-of-hospital cardiac arrests up to 70%, according to a new study. Cardiac arrest occurs when the heart abruptly stops beating properly and can no longer pump blood to vital organs throughout the body.

Researchers found that inhaling the tiny toxic particles in heavy smoke increased cardiac arrests in both men and women, particularly in people 35 and older and in communities with lower socioeconomic status.

“Particulate matter from smoke that is inhaled can penetrate deeply into the lungs, and very small particles may cross into the bloodstream. These particles can create an inflammatory reaction in the lungs and throughout the body,” Ana G. Rappold, one of the study’s authors, said in a news release. Rappold is a research scientist at the U.S. Environmental Protection Agency’s Center for Public Health and Environmental Assessment in the Office of Research and Development.

“The body’s defense system may react to activate the fight-or-flight system, increasing heart rate, constricting blood vessels and increasing blood pressure. These changes can lead to disturbances in the heart’s normal rhythm, blockages in blood vessels and other effects creating conditions that could lead to cardiac arrest.”

Researchers aim to shed light on the effects of wildfire smoke on the heart, which are not as well-known as respiratory effects. The study, published Wednesday in the Journal of the American Heart Association, examined cardiac arrests in 14 wildfire-affected counties in California between 2015 and 2017.

The researchers compared smoke exposure around the time of the cardiac arrest to the exposure over three previous weeks. Cardiac arrest risk increased on days of heavy smoke exposure and for several days afterward, peaking at 70% higher on the second day after smoke exposure.

Cardiac arrests outside the hospital are more dangerous because they often are not treated with CPR or a defibrillator to shock the heart back into a normal rhythm.

The researchers advise avoiding activities that involve exertion and exposure when there is wildfire smoke. They suggest people stay inside with doors and windows closed and use high-efficiency air filters in air conditioning systems.

“In recent decades, we experienced a significant increase in large-scale wildfires,” Rappold said. “Therefore, more people are being exposed to wildfire smoke.”

If you have questions or comments about this story, please email