Wildfires Have Significant Impacts on Respiratory Health

In recent years, wildfires in the United States have become increasingly frequent, larger, and more widespread. Research from the University of Colorado Boulder found that there were more fires in the span of a 13-year period from 2005 to 2018 than in the previous 2 decades, with fire frequency doubling on the East and West coasts and quadrupling in the Great Plains regions.¹ Certain regions have seen dramatic surges in wildfires in 2025 alone, including in Los Angeles County earlier this year and more recently in New Jersey’s Pinelands.²

There were more fires in the span of a 13-year period from 2005 to 2018 than in the previous 2 decades. | Image Credit: Erin – stock.adobe.com

Wildfires can have significant impacts on the respiratory health of those exposed to elevated levels of fine particulate matter (PM2.5).³ PM2.5 describes airborne particles with a diameter of 2.5 μm or less, approximately 30 times smaller than the width of a human hair. PM2.5 can be a mix of various substances, including dust or soot; biological matter such as pollen, bacteria, mold, or animal dander; and liquid or solid particles in aerosol.⁴

“Wildfires generate intense air pollution composed of burned brush and trees. When the fires encroach into the wildland-urban interface, they can also include burned structures and vehicles,” May-Lin Wilgus, MD, a pulmonologist and associate clinical professor at the David Geffen School of Medicine at UCLA in Los Angeles, California, said in an interview with Drug Topics. “The pollution includes fine particulate matter, ozone, nitrogen oxides, and volatile organic compounds, all of which can be transported in a smoke plume miles away from the actual fire.”

These particles are invisible to the naked eye, and as opposed to larger particles that may only reach the back of the throat, PM2.5 can travel deep into the lungs when inhaled. This means it can also penetrate the bloodstream, causing inflammation, oxidative stress, and damage to DNA.

“When inhaled, the fine particulate matter in wildfire smoke particularly impacts the smaller airways. While anyone can experience respiratory symptoms from this type of exposure, people with existing lung disease such as asthma and COPD [chronic obstructive pulmonary disease] are most at risk of developing worsening airway inflammation and reactivity that manifests as an exacerbation of their lung condition,” Wilgus said. “In firefighters, there are associations between wildfire exposure and new-onset asthma and possibly between wildfire exposure and lung cancer; however, this has not been shown in the general population.”

During the Los Angeles County wildfires in January 2025, the CDC reported an 8-fold increase in emergency department visits, particularly in vulnerable populations including children and older adults.² Common symptoms included shortness of breath, respiratory distress, and acute bronchitis.

“In people with asthma or COPD, wildfire smoke exposure is associated with worse symptoms, increased medication use, and increased emergency department visits and hospitalizations,” Wilgus said. “During or after a wildfire, I often see patients with lung conditions presenting with worse cough, breathlessness, and wheezing. Some people returning to homes damaged by fire are also sensitive to exposure to residual ash in the home.”

Patients should be aware of the risks that wildfire smoke can pose to their health, particularly those with a preexisting lung condition.

“The best measure is to avoid exposure, which may include evacuation when indicated. Otherwise, other measures include staying indoors, closing the doors and windows, running the HVAC [heating, ventilation, and air conditioning] for air filtration, and using HEPA [high-efficiency particulate air] filters to clean indoor air,” Wilgus said.

Pharmacists can play a key role in assisting patients during public health crises such as wildfires. Patient education and emergency preparedness are 2 crucial ways they can contribute.

“Clinicians should help counsel patients at risk from wildfire smoke exposure to be prepared with enough routine and emergency medications at home to avoid going outside,” Wilgus said. “They should also help patients with lung conditions develop an action plan to treat an exacerbation early, which may include rescue inhaler and nebulizer medications, and oral steroids if indicated. Pharmacists can be an important resource to help people who need extra medication for an exacerbation or because of an evacuation. They can also help patients who have limited access to supplies at home.”

Uninterrupted access to necessary medications is especially important for chronic conditions such as asthma and COPD. Pharmacists can help prevent patients from running out of medications by facilitating early refills. They can also help patients at risk avoid exposure to hazardous air conditions by offering curbside pickup options or coordinating mail-order deliveries.⁵

Pharmacists can also counsel them on wearing N95 or P100 masks correctly so they form a seal to the face, filtering out PM2.5 particles.⁶ Pharmacists can also help patients prepare for disasters by advising them on creating evacuation plans or preparing emergency medication kits in advance.

On a broader scale, pharmacists can also assist with public health efforts by participating in community screenings to assess the impact of wildfire smoke, which may include measuring vital signs and conducting surveys.⁷ These types of public health initiatives also provide an opportunity for medication counseling and patient education.

Although knowledge about the long-term effects of smoke from wildfires is still largely unknown, research is beginning to examine this topic in more detail. “The long-term effects and nonrespiratory effects of wildfire exposure remain mostly unknown, but this is an active area of investigation,” Wilgus said. “Recently, wildfire smoke exposure has been associated with adverse cognitive effects and risk for dementia.”

These findings are from a 2024 study conducted by researchers at the University of Washington in Seattle, who followed more than 1.2 million Kaiser Permanente Southern California members from 2008 to 2019.⁸ The study results also found that those in higher-poverty census tracts and racial and ethnic minority individuals were more likely to be diagnosed with dementia than higher-income or White patients.

Because PM2.5 penetrates the lungs and enters the bloodstream, it can also have profound impacts, including inflammation, oxidative stress, and vascular dysfunction. These effects, often combined with hot temperatures present during wildfires, can lead to increased rates of heart attacks. Research shows that exposure to dense smoke from wildfires has been associated with a 42% increase in emergency department visits for heart attacks and a 22% increased risk for ischemic heart disease within a day of exposure.⁹

In response to the fires in Los Angeles County in January 2025, a 10-year study, called the Los Angeles Fire Human Exposure and Long-Term Health Study, was launched to assess the long-term effects of wildfire smoke exposure, including respiratory, cardiovascular, neurological, reproductive, and immune system impacts.¹⁰ The study is a multi-institutional collaboration between researchers from Harvard T.H. Chan School of Public Health in Boston, Massachusetts; the UCLA Fielding School of Public Health; the University of California, Davis; and The University of Texas at Austin.

Pharmacists play a crucial role in mitigating respiratory health issues caused by wildfire smoke. By offering essential services, counseling, and guidance to affected communities, they can help protect patients from exposure to pollutants, prevent patients from running out of medications, and help patients prepare emergency kits in case of evacuation.

To read these stories and more, download the PDF of the Drug Topics May/June issue here.

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