Indoor air quality after a fire


soot and fire damage near front door
Photo: Cooperative Institute for Research in Environmental Sciences at the University of Colorado Boulder

Smoke, ash, and soot after a fire can deposit particulate matter, volatile organic compounds, such as benzene, and other chemicals on furniture, walls, floors, and other surfaces. Levels of chemicals inside homes that are severely smoke impacted likely will be higher than in less severely impacted homes. The chemicals will continue to be released into the air over the weeks following the fire, but they will reduce over time. Properly clean your home while protecting your health to reduce your exposure to particulate matter and these chemicals.

This information is for residents and businesses who are cleaning up ash inside buildings, not those cleaning around structures that were destroyed.


Whether you will experience health impacts from these substances depends on many factors, including what’s in the ash, how much of it and how long you’re exposed, and your health history and lifestyle factors.

Symptoms that may be related to exposure to ash or soot include repeated coughing, shortness of breath or difficulty breathing, wheezing, chest tightness or pain, palpitations, headaches and nausea or unusual fatigue or lightheadedness. Some of these symptoms also could indicate a COVID-19 infection, so people who may have been exposed to the virus should be tested.

  • Wear a well-fitted NIOSH-certified mask or respirator (such as an N-95 mask or a P-100 particulate respirator). Surgical masks and cloth masks will not protect your lungs from the fine particles of greatest concern.

  • Wear gloves, long-sleeved shirts, long pants, shoes and socks to avoid skin contact with ash or debris. If you get ash on your skin, in your eyes, or in your mouth, wash it off as soon as you can.

  • Avoid cleanup activities if you have heart or lung disease (including asthma), are an older adult, or are pregnant.

  • Keep children and pets away from ash and cleanup activities.

  • Clean for limited periods of time, and take fresh air breaks frequently.

  • If you have symptoms that may be related to exposure to smoke or soot, stop cleaning and consult your health care provider.

Air out your home

  • When possible, air out your indoor spaces by opening windows and doors.
  • If there is a lot of ash and debris outside your home, air out your home after debris has been cleaned up, and use air cleaners in the meantime.


Use air cleaners to help remove particles and odors

  • CDPHE recommends air cleaners with HEPA filters for particles and activated carbon filters for volatile organic compounds such as benzene.
  • Keep air cleaners on until the smells go away.
  • Do not use ozone generators in occupied homes. Ozone is toxic to breathe, and using one of these devices in the home can create a potential health risk. High ozone levels can damage plants and materials such as paints, rubber, other natural materials, electrical wire coatings, fabrics, and artwork. 
  • If you do use a device that purposely generates ozone in an unoccupied space, use caution. Be sure to thoroughly air out the space (at least four hours) before re-entering. More information on ozone generators. 
  • Two sources for finding air cleaners are:


Check your HVAC

  • Consider upgrading your HVAC filter to a MERV 11 or higher rated filter if your system can accommodate it.
  • Replace filters as they become clogged or monthly for up to a year after the surrounding area is cleaned.
  • Consider cleaning your HVAC ducts. More information on air duct cleaning.
  • Rinse off furnace air intakes and air conditioning units


Deep clean the surfaces of your home

  • Vacuum floors/carpet/rugs, drapes, furniture using HEPA-type vacuum cleaner or steam clean these surfaces.
  • Clean all surfaces in the home, including walls and ceilings.
  • Avoid actions that can stir up particles, such as dry sweeping and dusting.
  • Before sweeping hard surfaces, mist them with water to keep dust down.
  • Do not use harsh chemical cleaners or vinegar as they can react with chemicals in the ash. Soap and water are adequate to clean ash from hard surfaces.
  • Once your home is cleaned, take off shoes and wipe pets’ paws when coming inside.