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Wildfire season has begun and the North American seasonal fire report predicts significant fire activity for much of the US later this summer. Americans are more likely than ever to encounter air that contains particulate matter less than 2.5 µm in diameter (known as PM2.5), often generated by the combustion of carbon-based fuels. A compound pollutant, PM2.5 contains a variety of substances that may cause or exacerbate cardiorespiratory disease.
Although the Trump Administration has attempted to roll back a slew of regulations aimed at reducing air pollution, the Environmental Protection Agency (EPA) still maintains resources for clinicians for how to talk to patients about the potential harms from poor air quality.
One such document, the EPA’s Particle Pollution and Your Patients’ Health Course, encourages clinicians to explain to patients the cardiovascular risks linked to particulate matter and the steps they can take to protect themselves from exposure to these pollutants.
“The goal is to increase awareness of PM exposure, who can act to reduce exposures and protect their health by paying attention to the AQI [Air Quality Index], changing activity plans if air quality is poor, and air cleaners that can be used at home,” the EPA press office told Medscape Medical News, referring to the AQI, a color-coded tool used to communicate levels of air pollution.
“Worldwide, cardiovascular events make up the majority of pollution-related fatalities,” said Colin Phillips, MD, chair of a working group on climate change for the American College of Cardiology and a proponent of the EPA’s educational resource.” We want to give patients tools to protect themselves and prevent cardiac events,” he said, noting that bad air quality days are more common and pollution is a growing problem.
Rising Toll
Globally, 8 million deaths a year are attributable to polluted air, according to 2024 estimates. Air pollution is the leading environmental contributor to global morbidity and mortality, more than many other common risk factors such as physical inactivity or smoking, according to research published in May. By 2045, the number of deaths attributed to cardiovascular disease could exceed 12 million.
Smoke travels hundreds of miles to harm air quality far from the fire, according to the EPA’s Wildfire Smoke and Your Patient’s Health course, which includes handouts explaining how smoke can trigger cardiovascular events in people with underlying diseases.
Now, emerging evidence suggests wildfire smoke exposure may be even more harmful than other types of air pollution. Long-term exposures to wildfire smoke has been linked to a higher risk for heart failure than exposure to particle pollution that isn’t fire related, according to research published in July.
Also accumulating: detailed data on the effects of long-term exposure to particulate matter. Per the World Heart Federation, exposure to PM2.5 has a cumulative effect, with prolonged exposure magnifying risks to cardiovascular health.
“Just as ultraviolet light causes skin damage over time, air pollution causes cumulative injury to the cardiovascular system,” Juyong Brian Kim, MD, assistant professor of medicine at Stanford University School of Medicine in Stanford, California, told Medscape Medical News. “The repeated insult leads to chronic inflammation, oxidative stress, and blood vessel damage. This ‘invisible’ accumulation of harm increases long-term risk for heart attacks, strokes, and other diseases, especially in vulnerable individuals.”
Kim and his colleagues published a study in May, showing toxicants can alter the epigenome, and environmental exposures may have transgenerational impacts, influencing disease risk in future generations.
What To Talk About When You Talk About Risk
Phillips practices in Portland, Maine, where recent Canadian wildfires have clouded the skies. Even so, pollution and heart risk are not always top of mind for his patients, he said. “But when we make the connection, they understand it and want to protect themselves. The EPA course is a good way of bringing it back to the bedside and giving real-life examples to work from,” he said.
Martha Gulati, MD, director of preventive cardiology at Cedars-Sinai Medical Center in Los Angeles, said it was natural to talk to patients during the January wildfires. “I explained why I was concerned about their exposure, I could use myself as an example: “I don’t have the risks that you do, and I’m wearing a mask outside,” she’d say.
Infographics on clinic walls help start conversations. Besides the EPA, good resources include
Timing matters, according to Robert Tighe, MD, associate professor of medicine at Duke University School of Medicine in Durham, North Carolina, who suggested talking to patients after an acute event. He has found patients are more receptive to considering risk factors such as air pollution exposure after they’ve experienced an event such as a heart attack, and they are recovering in the hospital.
Kim, on the other hand, takes time to make his case. “I explain that high levels of air pollution pose a real risk for cardiovascular problems, including heart attacks, strokes, and arrhythmias, and the risk is pronounced in those with preexisting conditions such as coronary artery disease, diabetes, obesity, or advanced age,” he said. “While acute exposures are harmful, long-term effects of chronic exposure may be even more damaging. Air pollution acts as a silent, cumulative stressor.”
Can Patients Protect Themselves from Bad Air?
For the American Heart Association’s 2020 scientific statement, Sanjay Rajagopalan, MD, director of the Cardiovascular Research Institute at Case Western Reserve University’s School of Medicine in Cleveland, has studied the effectiveness of personal protection equipment and strategies — such as using various types of face masks, air filters, avoiding known hotspots — to reduce the health harms of poor air quality.
Potentially helpful steps to take when PM2.5 levels are high include staying indoors with windows closed, using portable HEPA-filtering air cleaners to create a clean air room, and setting a central ventilation system to recirculation mode with a high-efficiency particle filter in place.
Research has yet to prove that mask use can reduce heart events, but some data show wearing N95 respirators may improve surrogate markers of cardiovascular risk, such as blood pressure.
Without better monitoring and forecasting, the effectiveness of protections is limited, according to the review. Improved access to monitoring devices is much needed.
More overall research is needed, not just on measuring pollutants but on communication. In theory, PM2.5 patient education sounds like a good idea. But there isn’t an evidence-based map to guide providers. “I hope that when physicians talk about it to patients they may listen; but there is no data to support this,” Gulati said.
“After the fires in Los Angeles, my patients did heed my advice,” she added. “We need clearer guidance on how to protect ourselves. Advocacy and lobbying to improve all pollution will be a more helpful strategy in the long run.”
Cardiovascular risk factors aren’t only in the air, she pointed out; all pollution (light, sound, soil, water) affects the heart. “If you can inhale it, ingest it, or have dermal contact to it, pollution has the potential to increase cardiovascular risk. Whether by inflammation, autonomic dysfunction, activating the thrombolytic pathway or pituitary adrenal axis, or by causing pulmonary inflammation, exposures can cause cardiovascular disease,” she said.
For Phillips, counseling about environmental risks is its own reward. “Knowing that smoke from an uncontrolled wildfire is covering your city can create a sense of helplessness, but there are small things you can do to protect yourself and bigger things systematically that can limit the extent of future wildfires, such as reducing fossil fuel dependence,” he said.
“Anything we can do to increase our ability to protect ourselves and care for each other is a positive thing.”
The sources in this story reported having no relevant financial conflicts of interest.
Denise Maher is a freelance journalist based in Brooklyn, New York. She has been writing about personal and public health for over 25 years.
