Study: Breathing wildfire smoke linked to increased risk of cardiac arrest

(CN) — California wildfires often uproot large swaths of people as they flee wind-whipped flames with plumes of smoke so massive they are visible from space.

A new study says smoke from California wildfires also increases the risk for cardiac arrest among individuals who cannot avoid breathing in the harmful particulates. This issue, the study argues, highlights a class divide unique to fire-prone regions of the world.

Before leaving office in 2019, then-California Governor Jerry Brown referred to the state’s perpetual fire season as the “new normal” with emergency crews responding year-round to wildfires.

In October 2017 alone, Northern California saw 250 fires burning over 245,000 acres, according to the California Department of Forestry and Fire Protection. At the time, the city of Napa had the nation’s poorest air quality due to high levels of particulates and schools as far as 50 miles away from the flames were closed due to the haze.

A cardiac arrest is an abrupt electrical disturbance to the heart and different from a heart attack but just as deadly, according to the authors of the study published in the American Heart Association’s scientific journal. An out-of-hospital cardiac arrest can be fatal: if someone does not perform CPR or use a defibrillator to jumpstart the heart, a patient could die in minutes.

The study published Wednesday reviewed cases of people who had cardiac arrests in 14 wildfire-affected counties in California from 2015–2017.

Heavy smoke inhaled into the lungs can provide a vehicle for small particulates into a person’s bloodstream, says study author and research scientist Ana Rappold with the U.S. Environmental Protection Agency.

Smoke exposure on the day of the out-of-hospital cardiac arrest was compared to the exposure to smoke on the same day of the week in the three prior weeks. Researchers also reviewed exposure to smoke one to three days before the medical episode on the corresponding days in three weeks before the event.

The results showed the risk for a cardiac arrest was 70% higher on the second day after exposure to heavy smoke density. Both men and women were at greater risk for experiencing cardiac arrest, including groups of people as young as 35 years old who were exposed to heavy smoke, according to the study’s results.

Previous studies show cardiac arrests can likely occur in older adults but Rappold’s study shows that younger people, aged 35–64, may not be aware that they are being exposed to particulates in heavy smoke.

The risk is exacerbated in lower-income communities. Both medium and heavy smoke exposure greatly increased the risk of cardiac arrest in communities where 20% or more of people who live below the poverty line.

“People in a higher socioeconomic status group who have pre-existing cardiopulmonary conditions may be better able to take effective action to decrease exposure, such as staying indoors, using portable air filters or using effective respirator masks. They may also be more likely to live in homes with air conditioning and efficient air filtration,” Rappold said in a statement accompanying the study.

The study’s small sample size limited the researchers’ ability to determine how the risk factors varied by gender and age.

The EPA did not immediately respond to requests for comment.

Last year, researchers from NASA and the National Oceanic and Atmospheric Administration announced a joint campaign to study the effects of wildfires and agricultural fires on air quality and the climate.