Wildfire season can affect more than the air outside. Smoke can travel long distances, and fine particles from wildfire smoke can enter homes through open windows, doors, ventilation systems, and other pathways.

That means staying indoors doesn't always mean you're protected from wildfire smoke.

The good news is that you can take several practical steps to reduce the amount of smoke entering your home and improve your indoor air quality.

From checking the AQI to using an air purifier, here are 7 ways to protect your indoor air during wildfire season.

Why Is Wildfire Smoke Dangerous?

One of the biggest concerns in wildfire smoke is fine particulate matter, or PM2.5.

PM2.5 refers to particles that are 2.5 micrometers or smaller. Because these particles are so small, they can remain suspended in the air and be inhaled deep into the respiratory system.

Wildfire smoke can contain particulate matter along with other pollutants. When outdoor air quality becomes unhealthy, reducing your exposure to wildfire smoke is important—and that includes reducing the amount of smoke that enters your home.

In simple terms: wildfire smoke is not just an outdoor problem. Your indoor air can be affected, too.

1. Check the AQI Before Opening Your Windows

The Air Quality Index (AQI) is one of the easiest ways to know what outdoor air quality looks like in your area.

During wildfire season, check the AQI and wildfire smoke conditions before opening your windows or doors.

You can check:

• AirNow.gov
• The AirNow Fire and Smoke Map
• Your state or local air quality agency
• Local weather and air quality alerts

If outdoor air quality is poor because of wildfire smoke, keep your windows and doors closed.

And don't rely only on what the sky looks like. Smoke may not always be visible, so checking the AQI is a better way to decide when to ventilate your home.

2. Keep Windows and Doors Closed When Smoke Levels Are High

Opening a window is usually an easy way to refresh a stuffy room.

But when wildfire smoke is outside, opening your windows can bring that smoke indoors.

Keeping windows and doors closed helps reduce the amount of outdoor smoke entering your home.

Also check for other pathways where outdoor air may enter, including:

• Gaps around doors
• Poorly sealed windows
• HVAC fresh-air intakes
• Window air conditioners
• Other openings connected to the outdoors

When outdoor air quality improves, you can open your windows temporarily to ventilate your home.

The goal isn't to keep your home sealed all the time. It's to avoid bringing polluted outdoor air inside when AQI conditions are poor.

3. Set Your HVAC System to Recirculate

If your air conditioner or HVAC system has a recirculation mode, use it during smoky conditions.

Recirculate mode reduces the amount of outdoor air being brought into your home while allowing your HVAC system to continue circulating indoor air.

If you have central HVAC, consider using a high-efficiency filter, such as MERV 13 or higher, if your system can accommodate it.

However, not every HVAC system is designed for every filter rating. Check your system specifications or manufacturer's recommendations before changing to a higher-efficiency filter.

During wildfire smoke events, your HVAC system and air purifier can work together:

Keep outdoor smoke out → recirculate indoor air → filter airborne particles.

4. Run an Air Purifier Before the Smoke Gets Bad

One of the easiest ways to prepare for wildfire season is to have an air purifier ready before you need it.

During a smoke event, a properly sized portable air cleaner can help reduce airborne particles indoors. For best results, choose a unit appropriate for the room size and run it consistently when outdoor air quality is poor.

Choosing an Air Purifier for Wildfire Smoke

When choosing an air purifier for wildfire smoke, room size is an important factor—but it's not the only one. Think about how you use the space and what other indoor air concerns you want to address.

Airthereal offers several types of air purifiers and air-care solutions, making it easier to choose a model based on your home's specific needs.

• For everyday air purification: Airthereal's HEPA air purifiers are designed to help remove airborne particles such as dust, pollen, smoke, and odors. Options like the Pure Morning APH260 and APH320 Smart WiFi Air Purifier are designed for everyday home use in different room sizes.
• For homes with pets: If pet hair, dander, and odors are also part of your indoor air concerns, the Glory Days AGH400 Pet Air Purifier is designed specifically for pet-friendly homes and everyday pet-related air concerns.
• For dry indoor air: If wildfire season overlaps with a period when indoor air feels dry, an air purifier and humidifier combo can help you address both air filtration and humidity in one device. Airthereal's Ethereal Rain AEH300 and AEH800 combine air purification with humidification for everyday home comfort.
• For humid indoor spaces: If your home tends to feel damp, the Zephyr AZH200 2-in-1 Air Purifier & Dehumidifier combines air purification and dehumidification in one system, helping you manage both airborne particles and excess moisture.

The right choice depends on your room size, household needs, and indoor environment. If wildfire smoke is your primary concern, start by choosing a purifier appropriately sized for the room and designed to filter airborne particles. Then consider additional features—such as pet-focused odor control, humidification, or dehumidification—based on what your home needs year-round.

👉 Explore Airthereal's HEPA Air Purifiers →

How to Get More From Your Air Purifier

Once you have the right-sized unit, placement and usage matter, too.

• Keep doors and windows closed during periods of heavy smoke.
• Place the purifier in a frequently occupied room.
• Give the unit enough clearance for proper airflow.
• Use a higher fan speed when outdoor air quality is poor.
• Keep replacement filters available so the purifier is ready when you need it.

You don't necessarily need to run an air purifier in every room. Start with the spaces where you and your family spend the most time, such as the bedroom, living room, home office, or family room.

Think of your air purifier as part of a broader wildfire-season strategy—not a replacement for checking AQI, limiting outdoor smoke infiltration, or managing your HVAC system.

5. Know When to Replace Your Air Purifier Filter

Wildfire smoke can load up an air filter faster than normal indoor conditions.

So don't rely only on your usual replacement schedule.

During heavy smoke events, check the filter more frequently and replace it when it becomes dirty or starts to smell like smoke.

Signs Your Filter May Need Replacing

Look for signs such as:

• The filter looks visibly dirty
• It has become dark or gray
• You notice a smoky smell
• Airflow appears weaker
• The purifier indicates that the filter needs replacement

Keeping spare filters at home is also a smart part of wildfire-season preparation.

If you live in an area that regularly experiences wildfire smoke, having a replacement filter ready can save you from having to wait until the filter is heavily loaded.

6. Reduce Activities That Add More Particles Indoors

When outdoor smoke is already affecting air quality, try not to add unnecessary pollution inside.

Limit activities that can increase indoor particulate matter, including:

• Burning candles or incense
• Using fireplaces
• Frying or broiling food
• Smoking or vaping
• Using aerosol sprays
• Vacuuming without appropriate filtration

If you need to cook, choose methods that produce less smoke and use your kitchen exhaust as appropriate.

When outdoor air quality is already poor, keeping indoor particle sources to a minimum can make it easier to maintain cleaner indoor air.

7. Create a Cleaner-Air Room

If wildfire smoke is particularly heavy, consider designating one room as a cleaner-air room.

Choose a room that:

• Has few windows and doors
• Can be closed off from the rest of the home
• Has an appropriately sized air purifier
• Is comfortable enough to spend extended periods of time in

Keep the room closed as much as possible and run the air purifier consistently.

This can be especially useful if maintaining cleaner air throughout your entire home is difficult.

A bedroom, home office, or smaller living area can often work well because it's easier to keep the space closed and concentrate air-cleaning efforts in one place.

Wildfire Season Indoor Air Checklist

Before the next smoke event, make sure you have these basics ready:

Check your local AQI and wildfire smoke forecast

Make sure windows and doors close tightly

Learn how to switch your HVAC to recirculate

Check your HVAC filter

Have an appropriately sized air purifier ready

Keep replacement filters on hand

Identify a cleaner-air room

Know which indoor activities can add more particles to the air

Frequently Asked Questions About Wildfire Smoke and Indoor Air

Can wildfire smoke get inside my house?

Yes. Wildfire smoke can enter homes through open windows and doors, ventilation systems, gaps, and other pathways. How much smoke enters depends on the building, ventilation system, and outdoor conditions.

Does an air purifier help with wildfire smoke?

A properly sized portable air cleaner can help reduce airborne particles from wildfire smoke indoors. For best results, choose a unit appropriate for the room and run it consistently during smoky conditions.

Should I run an air purifier with the windows closed?

Yes. When outdoor air quality is poor because of wildfire smoke, keeping windows and doors closed while running an appropriately sized air purifier can help reduce indoor particle levels.

How often should I change my air purifier filter during wildfire season?

There isn't one universal replacement schedule. Check your filter more frequently during wildfire smoke events and replace it when it becomes dirty, airflow decreases, or the filter develops a smoky smell. Heavy smoke may require more frequent replacement than normal.

What AQI is unsafe for wildfire smoke?

The AQI is designed to communicate how clean or polluted outdoor air is and what associated health concerns may be. During wildfire smoke events, pay particular attention to local AQI and smoke forecasts rather than relying only on whether smoke is visible.

If air quality is unhealthy, limit outdoor exposure and take steps to reduce smoke entering your home.

 

Be Ready Before the Smoke Arrives

Wildfire smoke can change outdoor air quality quickly. Preparing your home before smoke arrives means you won't have to wait until the air is already unhealthy to start taking action.

Check the AQI. Close the windows. Recirculate your HVAC. Run your air purifier. And keep a fresh filter ready.

A few simple preparations can help you create a cleaner, more comfortable indoor environment when wildfire smoke is in the air.

Be ready before the smoke arrives.