Air Quality and Wildfire

Updated June 6, 2025

Summer and fall air quality in Spokane can often be impacted by regional wildfires. Smoke from wildfires that are far away can also cause unhealthy air pollution in the Spokane area. This can result in air pollution that is sometimes unhealthy for all. During times of poor air quality, Spokane Regional Health District (SRHD) and Spokane Regional Clean Air Agency (Spokane Clean Air) urge residents to understand the health risks associated with wildfire smoke and take precautions to protect their health. 

Current air quality information is provided by Spokane Regional Clean Air Agency and updated every hour using the Air Quality Index (AQI), which reports the level of air quality and health concern across six categories.

Statewide air quality information is available at Washington Smoke Blog.

Wildfire smoke is a mix of gases and fine particles, called PM2.5, from burning vegetation, building materials and other materials.¹ Wildfire smoke can make anyone sick, even someone who is healthy, if there is enough smoke in the air. Breathing in smoke can have immediate health effects, including¹:

• Coughing
• Trouble breathing normally
• Stinging eyes
• A scratchy throat
• Runny nose
• Irritated sinuses
• Wheezing and shortness of breath
• Chest pain
• Headaches
• An asthma attack
• Tiredness
• Fast heartbeat

While inhaling smoke isn’t good for anyone, some people are especially sensitive and more likely to experience health problems related to wildfire smoke, including the following²:

• Older adults over age 65. This is because they are more likely to have unrecognized heart or lung diseases.²
• Infants and children under 18. Their lungs and airways are still developing, and they breathe more air per pound of body weight than adults.
• Pregnant women. Both the mother and fetus are at increased risk of health effects.
• People who smoke because they are more likely to already have lower lung function and lung diseases. 

People with existing health conditions, such as the following, are also more likely to experience health effects²:

• Lung diseases such as asthma or chronic obstructive pulmonary disease (COPD), including bronchitis and emphysema.
• Respiratory infections, such as pneumonia, acute bronchitis, bronchiolitis, colds or flu.
• Heart or circulatory problems, such as dysrhythmias, congestive heart failure, coronary artery disease, angina, and prior history of heart attack or stroke.
• Diabetes because they are more likely to have an undiagnosed cardiovascular disease.

Respiratory symptoms such as dry cough, sore throat and difficulty breathing are common symptoms of both wildfire smoke exposure and some respiratory illnesses. See how the symptoms compare below. If you or someone you know is experiencing severe symptoms, such as difficulty breathing or chest pain, call 911.

If you have a fever, cough or shortness of breath, proceed as if you may have a respiratory virus, protect others by staying home, and call your health care provider to discuss testing and other possible reasons for your illness.

Here are some steps you can take to limit exposure to wildfire smoke.

• When a wildfire occurs in your area, watch for local news or health warnings about smoke and air quality. Pay attention to local air quality reports and public health messages and take extra safety measures such as avoiding time outdoors or limiting outdoor physical activity.
• If it is recommended you stay indoors, keep your indoor air as clean as possible by reducing smoke intake into your home. Close windows and doors unless it is very hot outside. Run an air conditioner if you have one but keep the fresh-air intake closed (set unit to recirculate) and the filter clean to prevent outdoor smoke from getting inside. Turn off fans that vent outside—like your bathroom fan. These pull in outside air through cracks around windows and doors.
• Reduce indoor pollution as much as possible when smoke levels are high. Limit use of anything that burns, such as candles and fireplaces. Do not smoke tobacco or other products. Limit activities such as vacuuming, dusting and sweeping, that stir up particulates in your home. Avoid using fragranced air fresheners, cleaners or essential oils, as they may trigger asthma or allergies. Reduce cooking, which creates heat and fine particles.
• Improve your indoor air filtration . Increase heating, ventilation and air conditioning (HVAC) filtration by setting your HVAC system or furnace fan to run continuously and use filters with a MERV rating of 13 or higher. You can also run a portable air clear with a HEPA filter or use a DIY box fan filter. Check and replace filters more frequently during wildfire smoke events.
• Follow your health care provider’s advice about medications and respiratory management plan if you have asthma or another lung disease. Call your provider if symptoms worsen.

Increase HVAC Filtration

You can improve the air quality in your home by reducing the fine particles coming into your home during smoke events. Your home’s HVAC system is the best way to reduce fine particles from wildfire smoke throughout your home, rather than in a single room. Increase the air filtration in your home HVAC system by using filters with a MERV rating of 13 or higher and using filters with the deepest pleat your system can accommodate. Close the air intake to keep wildfire smoke out. Make sure to consult your HVAC manual or consult with an HVAC professional before making improvements. Change the filter when dirty or indicated by manufacturer’s instructions. Check the filter more often during wildfire smoke season.

Use a Portable Air Cleaner with a HEPA Filter

A portable air cleaner with a HEPA filter can remove fine particles  from wildfire smoke in a single room. Select one that is rated for the size of room where you plan to use it. The rating is based on the square footage of the room and the Clean Air Delivery Rate (CADR). Consider the noise rating as well, as some can be quite loud. Choosing one rated for a larger room and then running it at a lower setting can reduce the noise.

Do not use ozone generators, personal air purifiers, or electrostatic precipitators and ionizers that produce ozone, which is a respiratory irritant. Check that it has been certified to avoid ozone exposures through the California Certified Air Cleaning Devices portal. Place it in a room where you spend time, with the windows and doors closed. Change the filter when dirty or indicated by manufacturer’s instructions.

Learn more about choosing a portable air cleaner.

Use a DIY Box Fan Filter

DIY-ing a box fan filter can be a less expensive option to reduce fine particles  from wildfire smoke in a single room. When building your own box fan filter it is important to understand their limitations and the potential risks.

Select a standard box fan and a filter with a MERV 13 rating of the same dimensions. There are different designs to consider, such as those where the filter is attached by bungee cord, the filter is taped on or screwed on brackets, or two filters are attached to create a triangle shape. 

Place the constructed DIY box fan filter in a room, ideally a small room where you spend time, with the windows and doors closed. Keep it away from a window or wall so that the front or back are not blocked. Do not run unattended and monitor for overheating to reduce the risk of fire. Change the filter when dirty.

Learn how to make a DIY filter

• Environmental Protection Agency DIY Air Filter Instructions
• Puget Sound Clean Air Agency DIY Air Filter Instructions
• Oregon Health Authority How to Build a Box Fan HEPA filter (video) English Spanish
• Colville Tribes Box Fan Filter DIY Users Guide (video)
• University of California - Davis How to Build a Corsi-Rosenthal Box (video)
• University of Utah DIY Air Filter (4-filter box fan) (video) English Spanish

During a wildfire smoke event, you can set up a clean room—a space set up to keep smoke and other particulate levels as low as possible. Use the following fact sheets to learn to learn how you can set up a clean room in your home or watch this video for instructions.

SRHD does not typically recommend face masks as the best option for members of the general public to reduce their exposure to wildfire smoke. It is better to stay indoors and keep indoor air clean.

If you need to use a face mask to be outside for a short period of time during a smoke event, wear an N95 or other NIOSH-approved respirator. An N95 respirator mask must fit well and be worn properly, or it won’t work. N95 respirators are not an option for everyone, as they are not recommended for children, not as effective with facial hair, and those with pre-existing conditions should first consult with a health care provider. 

Smoke particles are extremely small. Only masks with a tight seal offer protection against smoke particles. Even a well-fitted N95 mask that blocks fine particles will not block harmful gases. 

Cloth face coverings do not provide protection from breathing in wildfire smoke. Smoke particulates are much smaller than the respiratory droplets that carry viruses. Cloth will not block the harmful gases in wildfire smoke.

Getting regular exercise is very important for your health. However, when exercising, your air intake increases. If you exercise when it's smoky out, you will inhale more polluted air. If you are sensitive to smoke, consider limiting your activities when the air quality is in the Unhealthy for Sensitive Groups category. Please note that people with asthma or lung and heart conditions may be more sensitive to poor air quality, so it may be best to reduce indoor and outdoor activities when air quality is in the Moderate category.

Populations at increased risk for severe respiratory problems from wildfire smoke include children and adolescents, especially when active. Children under the age of 6 are most at risk for experiencing severe respiratory problems from wildfire smoke. When air quality conditions deteriorate into "unhealthy" ranges, the best thing to do is limit outdoor exposure.

For more information, please see the Washington State Department of Health Air Quality Guide for School Activities and Sports.

If there are concerns about indoor air quality in the workplace, check with your employer about keeping the air inside as clean as possible. The windows and doors should be kept closed. The building’s air conditioner or HVAC system should be used with the fresh-air intake closed and the filter clean to prevent outdoor smoke from getting inside. Ventilation fans that exhaust to the outside may need to be turned off, because they can pull smoky air into the building through windows, doors and cracks.³ Building maintenance or HVAC professionals can make recommendations for specific situations.⁴

According to Washington State Department of Labor & Industries’ (L&I) Wildfire Smoke Rules, employers are required to take steps to limit workers’ exposure to smoke when smoke particulates, known as PM2.5, reach certain levels.⁵

Large public, commercial, and multi-unit residential buildings are built with a wide variety of HVAC systems, which can be very complex. The EPA provides information on the steps that can be taken to reduce the impacts of wildfire smoke indoors in commercial or public buildings. 

When it’s smoky out and outdoor air quality is considered unhealthy or hazardous, it’s important to minimize health risks related to exposure to smoky conditions. Consider the following best practices from L&I⁵:

• Relocate work to less smoky areas.
• Reschedule work until the air quality improves.
• Reduce the level or duration of work that is physically demanding.
• Provide enclosed structures or rooms that supply filtered air.
• Provide vehicles equipped with air conditioning; in poor air quality conditions, employees should operate the air conditioning in "recirculate" mode and keep vents and windows closed.

According to L&I’s Wildfire Smoke Rule, employers are required to take steps to limit workers’ exposure to smoke when smoke particulates, known as PM2.5, reach certain levels.

Visit L&I’s website to learn more.

You may ask to voluntarily wear a NIOSH-approved dust mask at work, such as an N95, when smoke from wildfires enters the work environment.

Your employer may also permit you to voluntarily use other types of NIOSH-approved respirators, such as half-facepiece elastomeric respirators with HEPA cartridges, but any such use would need to comply with medical evaluations and other applicable requirements in the Respirators rule, Chapter 296-842 WAC.

According to L&I’s Wildfire Smoke Rule, employers are required to take steps to limit workers’ exposure to smoke when smoke particulates, known as PM2.5, reach certain levels.

Visit L&I’s website to learn more.

Wildfires can generate harmful gases, such as carbon monoxide. Wildfires often burn man-made materials such as buildings, vehicles and powerlines, which can produce a wide variety of hazardous gases and fine particles, such as lead,⁶ arsenic, formaldehyde,⁷ asbestos and benzene⁸. The fine and ultrafine particles in wildfire smoke can be inhaled deeply into the lungs and even cross over into the blood stream.⁹

When air quality is poor, demand for protection products is high. Prices could rise, or supplies might be sold out. Prepare for wildfire season by purchasing supplies in advance. Supplies you can buy ahead of time include:

• Replacement filters for your HVAC system
• DIY box fan air filters
• Portable HEPA air cleaners
• Replacement filters for your portable air cleaner
• N95 respirator masks 

If you are sensitive to wildfire smoke, talk to your health care provider in advance about how to protect your health during smoke events.