The American Heart Association (AHA) is issuing a stark warning as parts of the U.S. face a dual threat from Canadian wildfire smoke drifting south and soaring summer temperatures, creating a potentially deadly situation for cardiovascular health. The combination of extreme heat and air pollution from wildfires can trigger major cardiovascular events, even in people without known health conditions.
“Extreme heat and wildfire smoke each carry major risks, especially for people with chronic health conditions including heart disease. The combination of the two is extremely dangerous,” said Manesh R. Patel, M.D., FAHA, volunteer president of the American Heart Association. Patel emphasized that while respiratory issues are often the primary concern with wildfire smoke, the cardiovascular impact is equally serious and far-reaching.
The microscopic particles in wildfire smoke, known as fine particulate matter, are linked to increased cardiovascular risk. A study published in Circulation, the AHA’s flagship journal, found that the risk of fatal heart attacks nearly doubled during extreme heat waves combined with high levels of fine particle pollution. Women and older individuals faced even greater risks.
Additional research has connected smoke exposure to a higher risk of sudden cardiac arrest and increased emergency room visits for cardiovascular issues. A study in the Journal of the American Heart Association reported that exposure to heavy wildfire smoke raised the risk of out-of-hospital cardiac arrests by up to 70%. This risk was elevated across all demographics, including men and women, adults aged 35-64, and communities with lower socioeconomic status.
The AHA recommends several precautions to reduce exposure and protect heart health during these conditions. Staying indoors with windows and doors closed is advised, and using high-efficiency air filters can reduce indoor particulate matter by 50-60%, according to the AHA’s 2020 scientific statement on air pollution exposure. If a home lacks air conditioning, seeking alternative shelter may be necessary.
Outdoor activity should be limited, especially between noon and 3 p.m. when temperatures peak. If going outside is unavoidable, wearing a mask, avoiding exertion, and taking frequent breaks in shaded or cool areas are essential. Staying hydrated with water—avoiding alcohol and caffeine—and wearing lightweight, light-colored clothing can help manage heat stress.
The AHA also urges people to check on older adults and those with chronic conditions, who are at higher risk. Pets should be brought indoors as they can also be affected. Recognizing the signs of a heart attack—such as chest discomfort, upper body pain, shortness of breath, cold sweat, nausea, or lightheadedness—is crucial. In the event of heat stroke, which presents with a body temperature above 103°F, hot red skin, rapid pulse, confusion, or loss of consciousness, immediate medical help should be sought.
Knowing CPR can more than double the chance of survival in cardiac arrest. The AHA recommends using the AirNow.gov zip-code level tracking map from the U.S. Environmental Protection Agency to monitor current air quality. Staying informed about local health department alerts is also important.
“Protect yourself, be alert and prepared,” Patel said. “It could be the difference in saving your life or that of someone you love.” The AHA provides additional resources at heart.org.
