Wildfire smoke and health

Wildfire smoke turns sky yellow behind pine trees

Wildfire smoke is a mix of gases and particles from burning trees, plants, buildings, and other materials. Fine particles (also known as PM2.5) are the biggest concern for human health.

Wildfire season is typically from May through September in Colorado. Wildfire behavior is unpredictable, which makes it challenging to predict smoke concentrations. Climate change is also creating conditions that will lead to more frequent wildfires. It is important for Colorado families to have the information they need to make decisions.


Health impacts from wildfire smoke

Whether you will experience health impacts from wildfire smoke depends on many factors, including what’s in the smoke, how long you’re exposed, how much you’re exposed to, and your health history and lifestyle factors.

Breathing in wildfire smoke can:

  • Irritate the eyes, nose, and throat.
  • Cause wheezing, coughing, and difficulty breathing.
  • Worsen asthma, bronchitis, and other lung diseases.
  • Increase the risk of heart attack, heart failure, stroke, and premature death.
  • Affect mental health.

There is limited research on the long-term impacts of wildfire smoke on health. However, reduced lung function is tied to long-term exposure to wildfire smoke. 

For medical emergencies, call 911. See a health care provider if your symptoms get worse, don't go away, or disrupt your daily activities.


High-risk populations

Wildfire smoke can make anyone sick, but some groups are at higher risk: 

  • People with health conditions, such as asthma, lung disease, and heart disease.
  • Children and older adults.
  • Pregnant people.
  • People who work outside.
  • People with less access to health care.
  • People with less ability to pay for interventions, like air conditioning or portable air filters.

Reduce your exposure

Coloradans need to have information to make decisions for themselves and their families. Some of these recommendations may not always be practical or affordable. 

Limit activity outdoors.

  • Stay indoors when you can. This is especially important for children and other higher risk groups.
  • Use an N95 respirator outdoors.
    • Other kinds of masks, such as cloth, surgical, or paint masks, do not prevent breathing in smoke. 
    • People with heart or lung conditions should check with a doctor before wearing a respirator.
  • Reduce smoke in your vehicle.
    • Close windows and vents.
    • Run fans in recirculate mode.
  • Smoke can be worse at night. Take extra precautions if you need to go out, and close the windows when you are indoors. 

Protect indoor air quality.

  • Create a clean room in your home.
    • Close windows and doors.
    • Use fans to stay cool.
    • Reduce fine particle levels using the heating, ventilation and air conditioning (HVAC) system in your home.
      • Run the fan continuously. 
      • Close the outdoor air intake or use recirculate mode.
      • Use the highest Minimum Efficiency Reporting Value (MERV) for your system. A filter rated MERV 13 or higher is best to effectively reduce fine particle pollution in indoor air.
    • Consider using a portable air cleaner with a High Efficiency Particulate Air (HEPA) filter or make a filter fan.
    • If your home becomes too hot, consider temporarily relocating to another area.
  • Avoid activities that increase indoor air pollution. Do not:
    • Burn candles.
    • Use gas, propane, or wood stoves.
    • Use a fireplace to heat your home.
    • Use aerosol sprays.
    • Fry or broil food.
    • Smoke or vape.
    • Vacuum or sweep.
  • If you are unable to create a clean room in your home, seek out locations where air may be filtered such as malls, movie theaters, and community centers.

Be prepared to evacuate or relocate.

  • Plan your evacuation route and your destination. 
  • Gather financial and personal documents.
  • Put together a kit that contains medications and other important items you need.