Wildfire smoke is fundamentally different from everyday air pollution because its particles are small enough to bypass your upper airway and lodge deep in your lungs, where they trigger inflammation and restrict breathing. A Flathead Valley clinic in Montana is currently treating multiple patients for chronic obstructive pulmonary disease (COPD) and asthma exacerbations as smoke from large fires in Oregon and Washington settles over the region.

Why Is Wildfire Smoke More Dangerous Than Regular Air Pollution?

The culprit is particle size. Wildfire smoke is dominated by particulate matter smaller than 2.5 micrometers, which is roughly one-thirtieth the width of a human hair. These microscopic particles slip past the filtering structures of your upper airway and travel deep into the lungs, where they can even pass into the bloodstream.

"They don't get caught in our upper respiratory system; they actually go deeper into our lungs," explained Kerri Mueller, an air quality specialist with Missoula Public Health, adding that from there the particles can pass into the bloodstream and affect the rest of the body.

Kerri Mueller, Air Quality Specialist at Missoula Public Health

For people with COPD or asthma, this deep penetration is particularly dangerous. In someone whose airways are already narrowed by disease, the particles trigger additional inflammation and constriction. Rescue inhaler use climbs, oxygen levels can drop, and a person who was stable on their regular medications can slip into a serious flare-up within hours to a day of heavy exposure, rather than over weeks.

At Greater Valley Health Center in Columbia Falls, Montana, Dr. Timothy Nuce has observed this pattern firsthand. The air quality index in the area peaked at 211 on a recent Sunday, a level the federal scale rates as very unhealthy for everyone, before improving to 99 by Tuesday afternoon.

"Most commonly, they are seen and treated for chronic obstructive pulmonary disease, COPD, and asthma exacerbations," said Dr. Timothy Nuce, medical director at Greater Valley Health Center.

Dr. Timothy Nuce, Medical Director at Greater Valley Health Center

Who Is Most Vulnerable to Wildfire Smoke?

Risk from wildfire smoke is not evenly distributed. Certain groups face significantly higher danger than others.

• Highest-Risk Groups: People with COPD, asthma, or other chronic lung disease; people with coronary artery disease or heart failure; and outdoor workers who cannot avoid exposure.
• Secondary-Risk Groups: Older adults, pregnant people, infants and young children, and people with other chronic health conditions.
• Lower-Risk Groups: Most healthy adults and children recover quickly from smoke exposure, though they may experience temporary irritation like coughing, sore throat, or headache.

The distinction between temporary irritation and a medical emergency matters clinically. A scratchy throat and cough in a healthy person during a smoke episode are expected and usually resolve when air quality improves. However, increasing shortness of breath, a rescue inhaler that is not lasting as long as usual, chest tightness, or confusion in someone with lung or heart disease warrants contacting a clinician immediately. Severe difficulty breathing, chest pain, or altered mental status calls for emergency evaluation.

How to Protect Your Lungs During Wildfire Smoke Events

• Create a Cleaner Room: Keep windows and doors closed, run a portable air cleaner with a HEPA filter (which captures particles down to 0.3 micrometers), and limit activities that add indoor particles such as frying, burning candles, or vacuuming with a non-filtered vacuum.
• Use Effective Filtration: A MERV 13 furnace filter attached to a box fan is another effective option. Central air systems can help when set to recirculate with a high-efficiency filter.
• Protect Outdoor Exposure: For people who must be outside for work or recreation, wear a properly fitted N95 respirator and take frequent breaks to reduce cumulative exposure.
• Manage Medications: People with asthma should follow their existing asthma action plan and keep quick-relief medication accessible. Anyone with COPD should confirm they have an adequate supply of maintenance and rescue medications before the next smoke episode, since refills become harder to arrange during a flare.
• Monitor Air Quality Timing: Check current air quality readings rather than assuming the day matches yesterday. Air quality in western Montana has been worse overnight and in the early morning due to valley inversion patterns, when smoke settles into valleys and improves through the day as ground-level air warms and rises.

The practical translation is that a morning walk during an inversion can deliver a heavier dose of smoke than an afternoon errand. As evening conditions calm and mixing heights drop, overhead smoke sinks back into the valley floor, making overnight and early morning the most hazardous times.

Households that build a cleaner room and a medication plan now will not have to improvise during the next smoke episode. Fire activity in the Northern Rockies typically continues into September, and conditions can reverse within a day when winds shift. Residents can check current conditions through the federal fire and smoke map, which combines permanent monitors with temporary sensors deployed during fire season, and the Montana Department of Environmental Quality posts smoke forecasts describing where alerts are in effect.