Talking wildfire smoke health impacts with University of Minnesota
MINNEAPOLIS/ST. PAUL (7/13/2026) —Wildfire smoke is becoming an increasingly common part of summer across Minnesota. According to the Minnesota Pollution Control Agency, smoky skies are expected to be even more common this year, with 12 to 16 wildfire smoke impacts expected over the summer.
Sarah Lacher, PhD, with the University of Minnesota Medical School, Duluth Campus, talks about the impact of wildfire smoke exposure on health, why it’s harmful and ways to protect yourself.
Q: Why is wildfire smoke harmful to our health?
Dr. Lacher: Wildfire smoke is a complex mixture that changes depending on the fuel. Although the chemistry can change, toxic gases and small particles are always present. Particles that are 2.5 microns or less in diameter (PM2.5) are especially hazardous because when they’re inhaled, they travel deep down into our airways. Once there, PM2.5 causes inflammatory and oxidative stress, which disrupts the normal day-to-day jobs of important lung cells. These lung cells are pretty tough as they have the molecular tools to repair damage at first. However, if PM2.5 causes chaos for too long, the repair mechanisms in these cells cannot restore order, leading to lung and heart disease. Additionally, PM2.5 can initiate inflammatory and oxidative cascades that harm blood vessels and may compromise critical defenses like the blood-brain barrier.
Q: What are the short-term and long-term effects of wildfire smoke exposure?
Dr. Lacher: The primary tissues affected by both short and long-term exposures are the heart, lungs and blood vessels. The symptoms people experience depend on a range of factors, but current underlying diseases and the concentration of PM2.5 in the air are primary drivers. For short-term exposures, if people have asthma, COPD or other respiratory infections, their symptoms are likely to worsen in moderate AQI days. Overall hospitalizations and cardiovascular mortality also rise. As the AQI moves to unhealthy and hazardous levels, even healthy people are likely to experience irritation of their throat, nose and lungs. People are also reporting impacts on their mental well-being. Long-term exposure to hazardous wildfire smoke concentrations leads to significant impairment in lung function and these impairments have been measured in people for at least two years following the exposure. Additionally, the risks of cardiovascular, cancer and neurocognitive diseases also increase.
Q: Who is most at risk?
Dr. Lacher: Anyone with underlying heart or lung diseases like coronary artery disease, asthma, COPD or lung cancer is especially vulnerable, as wildfire smoke will worsen their symptoms. Current or former smokers or users of other inhaled recreational substances are also susceptible. Because pregnancy already carries inherent cardiovascular demands, wildfire smoke poses risks for both pregnant people and developing fetuses. Children are sensitive to wildfire smoke exposure, which can alter lung development, increase the risk of childhood asthma and potentially elevate disease risks later in life. People over the age of 65 are also at elevated risk of negative symptoms following wildfire smoke exposure, as are individuals with underlying inflammatory conditions such as obesity and diabetes. Finally, systemic racism and practices such as mortgage redlining have concentrated air pollution burdens in many communities of color and low-income populations, leaving these communities especially vulnerable as wildfire smoke adds to already elevated air pollution.
Q: What can I do to protect myself from wildfire smoke during poor air quality days?
Dr. Lacher: The fundamental principle of toxicology is that any substance can be hazardous, and it’s the dose that determines the toxicity. Thus, one of the primary ways to protect yourself is to limit the time and duration of exposure to wildfire smoke. People are advised to stay indoors during hazardous AQI days. Indoor air filtration systems can further reduce PM2.5 concentrations. Personal AQI monitors can provide real-time air quality data, and consumer grade options are available for both indoor air filtration and personal monitoring. Finally, there is hesitancy around wearing KN95 masks, and I fear that people may not understand how they work. KN95 masks are designed to filter particles as small as 0.3 microns; PM2.5 includes particles up to 2.5 microns, thus a well-fitting KN95 will prevent most of this harmful particle fraction from being inhaled.
Q: How does your research advance health in Minnesota?
Dr. Lacher: Our work seeks to dissect the cellular stress response pathways that are activated by wildfire smoke. Cells that regulate inflammation and barrier integrity in the lung are some of the first responders; these cells have evolved protective mechanisms that are activated after inhalation of wildfire smoke. However, these same repair mechanisms if overactivated can lead to disease. Using experimental data from cellular models, animal models and humans, we are characterizing the molecular drivers that determine cellular resistance or susceptibility to wildfire smoke, with the goal of developing therapeutic and prevention strategies to protect the most vulnerable people in our communities. We are also increasing community outreach on the Duluth campus and educating the public about the health risks of wildfire smoke and providing practical strategies to reduce exposure, which will help people in Northern Minnesota better protect themselves when the AQI is hazardous.
Dr. Sarah Lacher is an associate professor at the University of Minnesota Medical School, Duluth Campus. Her research focuses on characterizing cell-type specific patterns of gene regulation following exposure to inducers of stress.
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