Recently, poor air quality has impacted various U.S. states as smoke from Canadian and regional wildfires, along with summer ozone pollution, has created unhealthy conditions for millions. The situation arises from a mix of sources. Smoke from Canadian wildfires has moved into the Midwest and Northeast. Meanwhile, wildfires in the western U.S. are also contributing locally. As reported on July 19, 2026, by the National Interagency Fire Center, 40,560 wildfires have ignited in the U.S. this year. These fires have consumed over 3.8 million acres.
Additionally, hot, stagnant weather can exacerbate ground-level ozone pollution. This occurs when sunlight and heat react with pollutants from vehicles and industrial activities. Weak winds can keep this pollution concentrated near the surface, causing ozone and fine particle levels to rise.
Where Air Quality Alerts Are in Place
The National Weather Service issued Air Quality Alerts around July 19 and July 20 across multiple states:
- Indiana
- Illinois
- Ohio
- Pennsylvania
- Colorado
- Idaho
- Washington
- West Virginia
- Michigan
- Minnesota
- Iowa
- Wisconsin
- Oregon
Michigan’s officials issued a statewide alert for fine particulate pollution (PM2.5) from wildfire smoke. They noted a new smoke plume from Canadian fires had settled, predicting PM2.5 levels to be “Unhealthy for Sensitive Groups,” with ozone also rising quickly.
In Minnesota, heavy smoke expanded into east-central and south-central areas. The Minnesota Pollution Control Agency forecasted the Air Quality Index could reach “Red” or “Unhealthy” levels. In Iowa, officials indicated monitors near Dubuque, Cedar Rapids, Iowa City, Clinton, Davenport, and Muscatine recorded PM2.5 levels deemed unhealthy by the Environmental Protection Agency.
Wisconsin saw a statewide advisory with PM2.5 expected to reach “Unhealthy” to “Very Unhealthy” statuses in spots. Illinois alerts mentioned smoke and particulates, predicting ozone levels above “Unhealthy for Sensitive Groups.” Indiana’s alerts included PM2.5, smoke, and ozone concerns, while Ohio cited ground-level ozone in central counties and fine particulates in the Miami Valley.
Further west, Oregon, Idaho, Washington, and parts of Colorado dealt with smoke from regional fires. Advisories affected Spokane County, parts of Idaho, and Oregon counties where smoke threatened air quality.
Increased Wildfires Worsen Air Quality Threat
The deteriorating air quality is due in part to growing wildfire smoke contributions to air pollution. The Environmental Protection Agency highlighted a rise in large, destructive wildfires in the U.S. and beyond, leading to smoke clouds across massive areas and boosting PM2.5 pollution. From 2006 to 2020, data analysis showed smoke concentrations increasing and affecting more U.S. regions. Communities far from active fires are now frequently experiencing this decline in air quality.
Danger of Smoke Exposure
Wildfire smoke includes fine particles, or PM2.5. These particles can travel deep into lungs and enter the bloodstream. The Centers for Disease Control states that smoke harms people even hundreds or thousands of miles from the source. Studies link smoke exposure to more emergency and hospital visits and deaths.
Groups at risk include children, older adults, pregnant people, outdoor workers, and those with asthma, chronic obstructive pulmonary disease (COPD), heart disease, or other lung issues. Yet, when Air Quality Index (AQI) levels hit “Unhealthy,” everyone may experience effects.
Typical short-term symptoms are:
- Coughing or wheezing
- Shortness of breath
- Burning eyes, nose, or throat
- Chest tightness
- Fatigue or dizziness
- Palpitations or unusual heart symptoms
Long-Term Health Risks
A 2026 study in Science Advances estimated long-term smoke PM2.5 exposure led to about 24,100 deaths yearly in the lower 48 between 2006 and 2020. The study saw no “safe” exposure level and linked smoke to higher death rates.
A 2025 Stanford-led study estimated wildfire smoke exposure caused about 41,380 excess deaths annually from 2011–2020 in the U.S. They predicted smoke-related deaths could rise over 70% by 2050, with related economic damages potentially reaching $608 billion annually.
Research from the Harvard T.H. Chan School of Public Health connected smoke PM2.5 exposure with health impacts for up to three months after exposure. The study linked smoke to increased hospital risk for:
- Ischemic heart disease (coronary heart disease)
- Cerebrovascular disease (strokes, brain hemorrhages, aneurysms)
- Arrhythmia (irregular heartbeats)
- Hypertension (high blood pressure)
- Pneumonia
- Chronic Obstructive Pulmonary Disease (COPD)
- Asthma
Exercise Increases Smoke Exposure
Health officials advise reducing outdoor physical activity during smoke events. More intense breathing increases particle intake. The European Respiratory Society found people can inhale air at rates over eight times higher during exercise compared to rest. Everyday activities that might increase exposure include:
- Walking
- Jogging
- Hiking
- Cycling
- Gardening
- Playing outdoor sports
Studies referenced by the EPA linked smoke episodes to more asthma-related emergency visits. The CDC noted smoke can worsen respiratory, metabolic, and cardiovascular disorders like asthma, COPD, and heart failure.
The American Heart Association linked wildfire smoke to more emergency visits for heart conditions, including a 42% increase in heart attacks and a 22% rise in ischemic heart disease visits within a day of dense smoke, especially among those 65 and older. A July 2025 NIH-led study found fine particulate pollution was tied to cancer mutations in lung tumors of nonsmokers, making PM2.5 exposure a wider public health issue than respiratory concerns alone.
Protective Measures
Public health officials recommend checking sites like AirNow.gov or local air quality forecasts before outdoor activities. When smoke or ozone is high, consider:
- Staying indoors with windows and doors closed
- Using air conditioning with a high-efficiency filter, if available
- Avoiding strenuous outdoor activities
- Moving exercise indoors
- Wearing a well-fitting N95 mask outside
- Keeping asthma medication nearby
- Seeking medical help for chest pain, severe shortness of breath, or unexpected fatigue
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