Wildfire smoke can drift for hundreds of miles and sneak into buildings, even if the fire’s nowhere near you. Once it gets inside, it lowers air quality and can cause health problems, especially for kids, older folks, and anyone with breathing issues.
The best way to protect indoor air during a smoke event is to keep outside air out and actively filter what’s already indoors.
If you know how smoke moves and where it sneaks in, you can start sealing up your place, boost filtration, and set up cleaner-air spaces. These steps cut down on harmful particles and help you stay more comfortable when it’s nasty outside.
With a bit of prep, you can make your home or workplace safer during wildfire smoke events. Sealing cracks, tweaking HVAC systems, and using air purifiers all help add layers of protection.
Understanding Wildfire Smoke and Its Impact on Indoor Air
Wildfire smoke is a mix of gases and fine particles that can travel quite far and make its way into buildings. Once inside, these tiny particles hang around in the air or settle on surfaces, making indoor air worse and raising health risks, especially for people who are more sensitive.
What Is Wildfire Smoke?
Wildfire smoke comes from burning plants and other stuff, creating a complicated blend of pollutants. The biggest worry for indoor air is fine particulate matter, especially PM2.5, which are particles 2.5 micrometers wide or smaller.
These particles can float in the air for hours, even days. They’re so tiny they can get deep into your lungs if you breathe them in.
Besides PM2.5, wildfire smoke often brings carbon monoxide, VOCs, and other hazardous air pollutants.
The smoke’s makeup depends on what’s burning, how hot the fire is, and the weather. Even if a wildfire’s far away, wind can carry smoke hundreds of miles and mess with indoor air in places nowhere near the flames.
Health Risks of Smoke Exposure
People react to wildfire smoke differently, depending on their health, age, and how much they’re exposed. Kids, seniors, and anyone with asthma or breathing issues face the most risk.
Fine particles like PM2.5 can slip past the body’s usual defenses in the nose and throat, reaching deep into your lungs. You might start coughing, feel your throat get scratchy, or have trouble breathing.
If you already have heart or lung disease, smoke exposure can make things worse and might even land you in the hospital.
Even folks without health problems can get headaches, feel tired, or have irritated eyes when wildfire smoke is around.
How Smoke Infiltrates Indoor Spaces
Wildfire smoke can get into buildings in a few ways:
- Natural ventilation—open windows and doors let it in.
- Mechanical ventilation systems can pull in outdoor air.
- Air leaks—gaps around windows, doors, or spots where wires and pipes come in.
Once inside, smoke hangs out in the air or settles onto surfaces and inside your vents.
HVAC systems with a fresh air intake can suck in smoke unless you set them to recirculate. Window AC units, swamp coolers, and leaky ductwork can also let smoke sneak in.
Even tiny cracks in walls or gaps around pipes can let enough PM2.5 inside to drop your indoor air quality during a wildfire.
Sealing and Preparing Your Home Against Smoke Infiltration
Start by figuring out where outside air leaks in, then seal those gaps. Sealing up helps keep indoor air cleaner and makes your air filters work less during wildfire smoke events.
Identifying Entry Points for Smoke
Smoke usually gets in through small gaps around windows, doors, vents, and spots where cables or pipes enter. Even hairline cracks can let those fine particles through.
Check both inside and outside your home. Problem spots often include:
- Window frames and sashes
- Door edges and thresholds
- Attic hatches and crawl space vents
- Gaps around pipes, cables, and ducts
Try using a lit incense stick near these spots on a windy day. If the smoke moves or gets pulled in, you’ve found a leak.
People often forget about attics, basements, and garages, but these areas can let in a lot of smoke. Sealing them keeps smoke from spreading into living spaces.
Applying Weather Stripping and Caulk
Weather stripping helps seal moving parts, like door edges or window sashes. You can find it in foam, rubber, or vinyl—each works better for different size gaps.
For fixed cracks, caulk is usually the best bet. Use it around window frames, trim, and where siding meets walls. Silicone caulk handles weather well, while acrylic latex is easier to paint.
Here’s how to seal gaps:
- Clean the surface so the seal sticks.
- Measure the gap to pick the right weather stripping size.
- Apply caulk in a smooth, continuous bead for a tight seal.
Good seals last years and help block both smoke and drafts.
Using Door Sweeps and Window Seals
A door sweep blocks the gap between a door and the floor. Outdoor air loves to sneak in here, especially under exterior doors. Sweeps come in metal, vinyl, or brush styles.
For windows, try compression seals or adhesive foam strips to close up small gaps. In older houses, adding interior storm windows can help keep smoke out.
Make sure seals fit tightly but don’t stop doors or windows from closing. Swap out worn sweeps and seals before wildfire season so they’re ready when you need them.
Optimizing HVAC Systems and Filtration
Keeping smoke particles out of indoor air depends on your filtration quality and how you run your air handling system. Picking the right filter, installing it correctly, and limiting outdoor air intake can cut down on PM2.5 exposure.
Choosing the Right HVAC Filter
The Minimum Efficiency Reporting Value (MERV) rating tells you how well an HVAC filter works. Go for MERV 13 or higher to catch most fine particles, including wildfire smoke.
Check your HVAC system’s specs before upgrading. Some systems can’t handle the extra resistance from high-rated filters without losing airflow. If you’re not sure, ask a pro about the best filter your system can take.
Make sure filters fit snugly so air doesn’t slip around the edges. Gaps let unfiltered air circulate, which defeats the point. During heavy smoke, you’ll probably need to swap filters more often than usual.
Tip: Stock up on extra filters before fire season so you’re not caught off guard.
Upgrading to HEPA Filters
HEPA filters catch at least 99.97% of airborne particles down to 0.3 microns, including most PM2.5. You can use portable HEPA air cleaners in specific rooms, or, if your central HVAC allows, install HEPA-grade filtration.
Adding a HEPA filter to a central system often needs extra gear, like a separate air filtration unit hooked up to your ducts. These filters make fans work harder, so your system needs to handle the load.
If your home doesn’t have central HVAC, standalone HEPA air purifiers work well. Set them up in rooms where people spend the most time and run them on the highest safe setting when smoke is bad.
Setting HVAC to Recirculate Air
When it’s smoky outside, switch your HVAC system to recirculate so it doesn’t pull in outdoor air. This keeps indoor air moving through the filter instead of bringing in more smoke.
If your system has a fresh air intake, close it during smoke events. For window ACs, close the outdoor air damper and seal up gaps around the unit.
Set the fan to “On” instead of “Auto” so air gets filtered more often. This boosts particle removal, especially if you’re using a high-efficiency filter.
Using Air Purifiers for Cleaner Indoor Air
Air purifiers help reduce smoke particles indoors during wildfire events. Picking the right unit, using it properly, and keeping filters fresh all matter for cleaner air in your home or clean air room.
Selecting an Effective Air Purifier
A portable air purifier with a true HEPA filter works really well for catching fine smoke particles. HEPA filters trap stuff as small as 0.3 microns, which covers most wildfire smoke.
Match the unit’s Clean Air Delivery Rate (CADR) to your room size. A higher CADR means it cleans the air faster.
Skip devices that make ozone, since ozone can mess with your lungs. The California Air Resources Board lists air cleaners that don’t produce much or any ozone.
If you’ve got a whole-house system, running a central HVAC with a MERV 13 or higher filter helps—just make sure your system can handle it.
Placement and Operation of Portable Air Purifiers
Put the air purifier in the room where you hang out most, like a bedroom or living room. Keep it a few inches away from walls or furniture so air moves freely.
Close all windows and doors in that room to keep out smoke. If you can, use the purifier in a sealed clean air room for best results.
Run it on the highest safe fan speed when smoke levels are high. Letting it run nonstop works better than turning it off and on. In multi-story homes, you might need a unit on each floor.
Don’t put purifiers near moisture, heat, or dust sources, since that can mess with their performance or even break them.
Maintaining and Replacing Filters
Filters don’t work as well once they’re clogged. During wildfire smoke events, HEPA filters and pre-filters might need replacing more often than usual.
Check filters often. If they look dirty, dark, or start to smell, it’s time for a new one.
Some purifiers have filter change lights, but these might not keep up with heavy smoke use. Keep spare filters around during wildfire season so you’re not left without.
Follow the directions for cleaning reusable pre-filters. Don’t wash HEPA filters unless the manufacturer says it’s okay—washing can ruin their ability to trap smoke.
Creating a Clean Air Room
A clean air room helps you avoid smoke by using a well-sealed space with good air filtration. It works best if it’s away from indoor pollution and has an air purifier with a HEPA filter or something similar.
Choosing the Best Room
Pick a room you can close off easily and where you’ll be comfortable for a while. Bedrooms with attached bathrooms are great since you don’t have to walk through smoky areas.
Choose a space big enough for everyone in the house, but not so huge your air purifier can’t keep up. Check the purifier’s Clean Air Delivery Rate (CADR) to make sure it fits the room size.
Avoid rooms with lots of windows or vents you can’t seal. If you can, pick a room on the side of the house farthest from the smoke source. That way, less outdoor air leaks in.
Sealing and Equipping the Clean Air Room
Shut all windows and doors to keep smoke out. Add weather stripping or door sweeps to close up gaps.
Seal unused vents or ducts with plastic sheeting and painter’s tape, but leave essential ventilation open for safety.
Run a portable air purifier with a true HEPA filter, and crank it up to its highest safe setting. If you’ve got a central HVAC system, use a MERV 13 or higher filter and set the fan to “On” so it keeps air moving.
Skip activities that make indoor particles, like burning candles or frying food. Don’t vacuum unless your vacuum uses a HEPA filter. If it’s not too hot, avoid devices like some window air conditioners that pull in outside air.
Swap out filters as needed during smoke events, especially if they look dirty or start to smell. It’s smart to keep extra filters around, just in case.
Additional Protective Measures During Wildfire Events
You’ll need both prevention and active steps to cut down on smoke exposure indoors. Track air quality, avoid making more indoor pollution, manage ventilation, and use the right protective gear if you have to go outside.
Monitoring Outdoor and Indoor Air Quality
Knowing what’s happening outside helps you decide what to do during wildfire season. Check outdoor air quality using the EPA’s AirNow website or your local monitoring network. Focus on PM2.5 readings, since those tiny particles are the main trouble from wildfire smoke.
Indoor air quality can shift quickly if smoke sneaks in. A cheap indoor air quality monitor can spot particle spikes and let you know when you need to run filtration or tweak ventilation.
If the air outside gets better, even for a bit, you might open a window to freshen things up. But when smoke levels are high, keep those windows and doors shut tight.
Staying on top of air quality lets you adjust your actions and avoid extra exposure.
Limiting Indoor Activities That Generate Pollutants
When wildfire smoke is around, don’t add to the mess inside. Common things that make fine particles or chemical vapors include:
- Smoking or vaping
- Burning candles or incense
- Using gas or wood-burning stoves
- Frying or broiling food
- Spraying aerosol products
Vacuuming stirs up dust and particles unless your vacuum has a HEPA filter.
Cutting back on these activities helps keep PM2.5 levels down and makes air cleaners work better. Even small bits of indoor pollution can make things worse for anyone with asthma, heart disease, or breathing issues during a smoke event.
Just a few changes in daily habits can really help keep your air cleaner.
Using Exhaust Fans and Ventilation Wisely
Ventilation choices matter a lot during wildfire smoke events. Exhaust fans in kitchens and bathrooms can help remove indoor pollutants, but if your system pulls in outside air, it might bring in smoke too.
If you use an HVAC system, check if it has a fresh air intake. If it does, set it to recirculate or close the intake to limit smoke getting in. Using a MERV 13 or higher filter, if your system can handle it, will help trap more particles.
Evaporative coolers and some portable air conditioners can draw in smoky air. When you can, seal up gaps and avoid running units that aren’t sealed off from the outdoors.
It’s a balancing act—cooling off versus keeping smoke out.
Personal Protective Equipment for Unavoidable Outdoor Exposure
If you really have to go outside when air quality is bad, wear an N95 mask to cut down on inhaling fine particles. These masks filter out most PM2.5 if you fit and wear them correctly.
Make sure the mask seals tightly around your nose and mouth. Facial hair can mess with the fit. Surgical masks, cloth masks, or bandanas won’t protect you the same way from wildfire smoke.
Try to limit how much you exert yourself outdoors, since heavy breathing pulls in more smoke.
Stock up on N95 masks before wildfire season so you’re not caught off guard. Store them in a clean, dry spot to keep them working well.
Protecting Vulnerable Individuals and Pets
Wildfire smoke has fine particles that can bother your lungs, eyes, and throat. People with certain health issues and animals can get symptoms quickly, even if smoke levels aren’t that high. Taking the right steps can lower the risk of breathing problems and other health troubles.
Special Considerations for Respiratory Conditions
People with asthma, COPD, or other chronic respiratory conditions should keep a close eye on air quality. Even moderate smoke can set off coughing, wheezing, or shortness of breath.
Always have rescue inhalers or prescribed meds within reach. Following your doctor’s asthma or COPD action plan can help you stay ahead of symptoms.
Use a HEPA air purifier or a central HVAC system with a MERV 13 or higher filter if your system can handle it. Keep doors and windows closed, and skip fans that pull in air from outside.
People with heart disease, diabetes, or chronic kidney disease might feel smoke effects more, too. They should take it easy and stay inside unless they really need to go out. If new or worse symptoms show up, get medical advice quickly.
Safeguarding Children, Older Adults, and Pets
Kids breathe more air for their size than adults do, so they’re extra sensitive to wildfire smoke. Masks and respirators only work if they fit right—and honestly, most N95s just won’t fit little ones.
Older adults might have weaker immune systems or deal with health problems that put them at higher risk. They should stay inside somewhere with clean air. It’s best if they skip heavy activity when smoke is in the air.
Pets aren’t immune to smoke either. You might notice them coughing, rubbing at their eyes, or just acting more tired than usual. Keep your pets indoors where the air’s clean, and only let them out quickly for bathroom breaks.
Make sure they have fresh water. Hold off on any intense exercise with them until the air gets better.