Wildfire smoke can drift for hundreds of miles and sneak into buildings, even if the flames are nowhere close. Once it’s inside, the air can turn unhealthy fast, leading to breathing problems, especially for children, seniors, and folks with heart or lung issues.
The best way to keep indoor air safe during smoky days is to block smoke from getting in and filter the air you’re breathing.
During a smoke event, tiny particles can slip in through cracks around windows, doors, and vents. If you don’t take action, those particles pile up indoors and stick around, even after the outdoor air clears up.
Simple fixes—like sealing gaps, running good air filters, and setting up a clean air room—can really help.
If you know how smoke moves, how it messes with air quality, and which tools actually work, you can make your home a lot safer. Prepping now doesn’t just help during wildfire season; it pays off all year.
Understanding Smoke Events and Indoor Air Quality
Wildfire smoke and smoke from big burns can travel far and slip into homes, even if the fire’s not nearby. These fine particles and gases build up indoors, dropping air quality and raising health risks, especially for people with heart or lung problems.
What Is a Smoke Event?
A smoke event happens when smoke from a wildfire, controlled burn, or other big fire causes a clear and lasting drop in air quality.
This might be local if a fire’s close, or regional when winds push smoke hundreds or even thousands of miles.
People usually measure smoke events by the amount of particulate matter in the air, mainly PM2.5 and PM10. These particles are tiny enough to get past your body’s defenses.
During a wildfire smoke event, outdoor air can stay bad for hours or days. Smoke sneaks into buildings through tiny cracks, vents, or open windows and creates indoor air pollution that can be just as harmful as being outside.
How Smoke Affects Indoor Air Quality
Smoke brings in a mix of solid particles and gaseous pollutants. Once these get inside, they linger, especially if you don’t ventilate well.
Fine particles like PM2.5 can float in the air for a long time, making them easy to breathe in. Gases like carbon monoxide (CO) and volatile organic compounds (VOCs) can also sneak in and build up.
If the building pulls in outdoor air through HVAC systems without filters, indoor air gets worse. Activities like cooking, burning candles, or smoking indoors during a smoke event just add more pollution.
Even after outdoor smoke clears, particles can settle on surfaces and get kicked up again when you clean or move around, so exposure can stick around.
Key Pollutants in Smoke
Wildfire smoke is a complicated mix of stuff, including:
| Pollutant | Description | Health Concern |
|---|---|---|
| PM2.5 | Fine particles ≤2.5 micrometers | Penetrates deep into lungs, enters bloodstream |
| PM10 | Particles ≤10 micrometers | Irritates eyes, nose, and throat |
| Carbon Monoxide | Colorless, odorless gas | Reduces oxygen delivery in the body |
| VOCs | Organic chemicals that evaporate easily | Can cause headaches, irritation, and long-term health effects |
| Polycyclic Aromatic Hydrocarbons (PAHs) | Byproducts of incomplete combustion | Linked to respiratory and cardiovascular risks |
| Formaldehyde | Chemical gas from burning materials | Causes irritation and may have long-term effects |
The exact mix changes depending on what’s burning, how hot it gets, and the weather.
Health Risks of Smoke Exposure
Anyone can feel the effects of wildfire smoke, but some people are hit harder. Kids, older adults, pregnant women, and folks with asthma, heart disease, or other respiratory issues are especially at risk.
Short-term effects might be coughing, throat irritation, runny nose, and shortness of breath. Fine particles can set off asthma attacks and make lung or heart problems worse.
If you’re exposed to smoke particles like PM2.5 over and over, your risk of chronic lung disease and cardiovascular issues goes up.
Even healthy people might notice lower lung function or just feel tired during heavy smoke. Limiting indoor exposure is key if you want to protect your lungs and reduce the toll of air pollution on your body.
Preparing Your Home for Smoke Events
You can cut down on smoke getting inside by blocking entry points, improving filtration, and managing airflow. Tiny gaps or unsealed vents bring in fine particles, so focus on sealing, inspecting, and setting up your systems before the smoke rolls in.
Sealing Windows and Doors
Windows and doors are the main ways smoke gets in. Check for gaps around frames, sashes, and thresholds. Use weatherstripping for moving parts and caulk for fixed joints.
Install door sweeps on exterior doors to stop smoke from sneaking in underneath. For sliding glass doors, seal the meeting rail with foam strips.
In older homes, warped frames might need a temporary fix—plastic sheeting or painter’s tape works in a pinch. Make sure locks snap shut to help the seal.
If you’re in a commercial building, check entry vestibules and automatic door closers. These can let in smoke if they don’t work right.
Addressing Smoke Infiltration Points
Smoke can slip in through spots you might not notice, like wall vents, dryer vents, attic hatches, and gaps around utility lines. Find these and seal them when you can.
Cover unused vents with magnetic vent covers or plastic sheeting during smoke events. Only use active exhaust vents if you really need to for safety.
Close fireplace dampers and flues tightly. Even if you’re not using the fireplace, chimneys can pull in outside air.
In basements or crawl spaces, seal up gaps where pipes, cables, or ducts go through walls. Use fire-rated sealants for safety.
For apartments or commercial spaces, look at ventilation systems that link shared areas. These can move smoke between spaces if you’re not careful.
HVAC System Preparation
Your HVAC system can help or hurt, depending on how you set it up. If there’s a fresh air intake, close it or switch to recirculate mode so you’re not pulling in smoky air.
Upgrade to a high-efficiency HVAC filter—MERV 13 or higher if your system can handle it. ASHRAE says these work best for fine particles.
Run the fan all the time during smoke events to keep filtering the air. Swap out filters more often if smoke is heavy.
Check for duct leaks and seal them so unfiltered air doesn’t sneak in. Sometimes, you might need duct cleaning after a bad smoke event, especially if there’s ash or debris.
Air Filtration and Purification Solutions
When smoke hits, you need to pull out fine particles and harmful gases to protect your lungs. Good air filtration and purification can knock down things like PM2.5, volatile organic compounds (VOCs), and stubborn smoke smells.
Choosing the Right Air Purifiers
Pick an air purifier that matches your room size and the stuff you’re trying to filter out. The Clean Air Delivery Rate (CADR) tells you how fast a unit can clean the air.
A purifier with the right CADR for your room will do a better job. For example, a 300 CADR purifier is best for a room up to about 450 square feet.
Look for models with true HEPA filtration for fine particles and activated carbon for smoke odors and gases. Skip units labeled “HEPA-type” or “HEPA-like”—they usually don’t meet the real standards.
Think about noise, how often you’ll need to buy replacement filters, and energy use, especially if you’ll run it a lot.
HEPA and Activated Carbon Filters
HEPA filters trap at least 99.97% of particles as small as 0.3 microns, including smoke particles, dust, and pollen. They’re one of the best options for improving indoor air quality (IAQ) during wildfires.
Activated carbon filters go after gases and odors. They soak up volatile organic compounds and other chemicals from smoke. The more carbon in the filter, the longer it lasts and the better it works.
Some air purifiers have both HEPA and activated carbon in one unit. This combo knocks out both fine particles and harmful gases, which is perfect when there’s smoke.
Replace filters as often as the manufacturer suggests, or even sooner if smoke is really bad.
Upgrading HVAC Filters
Central heating, ventilation, and air conditioning (HVAC) systems can help clean your air if you use good filters. Standard ones usually only catch big stuff—not smoke.
Switch to a MERV 13 or higher filter to catch smaller particles, including smoke. Just make sure your fan and airflow can handle the thicker filter.
Keep the HVAC fan running all the time during smoke events to keep air circulating through the filter. Shut all doors and windows so unfiltered air doesn’t get in.
Check filters often since smoke can clog them up fast.
Portable Air Cleaners and DIY Options
Portable air cleaners are great for spaces without central air or for focusing on bedrooms and living rooms. Models with both HEPA and activated carbon filters give you the best shot at knocking down smoke particles and smells.
If you’re on a budget, try a DIY box fan filter—just tape a high-MERV furnace filter to the intake side of a regular box fan. It’s not as good as a certified air purifier, but it still helps in a pinch.
Set portable units away from walls and furniture so air can move freely. Run them on higher speeds when smoke is thick, though they might get a bit noisy.
Creating and Maintaining a Clean Air Room
A clean air room gives you a safe spot to escape smoke particles. The idea is to keep smoke out, maintain clean air, and have a place to breathe easier when it’s smoky outside.
Selecting the Best Room
The best clean room is inside your home, with few windows and doors. Bedrooms are a popular choice since you spend a lot of time there anyway.
A room with a bathroom attached is handy so you don’t have to go out as much. Make sure the space is big enough for everyone in your household.
Skip rooms with fireplaces, gas stoves, or anything else that creates indoor pollution. Pick a spot you can close off from the rest of the house to control airflow.
Sealing and Equipping the Space
Shut all windows and doors tight to keep smoke from sneaking in. Add weatherstripping or door sweeps if you see gaps.
Set up a portable air cleaner that’s rated for the room’s size. Go for one with a high-efficiency filter—MERV 13 or higher is best—and avoid anything that makes ozone. Run it on the highest safe setting.
If you don’t have a portable unit, build a DIY air cleaner with a box fan and a good furnace filter. Keep extra filters handy and swap them out if they look dirty or start to smell smoky.
Managing Air Flow and Entry
Try to keep the air in the room still and clean. If you have central HVAC, set the fan to On instead of Auto so air keeps moving through the filter. Close any fresh air intakes so you’re not pulling in smoke.
Don’t do things that make more indoor particles—skip smoking, candles, or frying food. Only use bathroom or kitchen fans if you really need to, since they can pull in smoky air from outside.
Limit how often you go in and out, since opening the door lets smoke in. When the air outside finally gets better, crack a window for a bit to air out the space, then seal it up again to keep things clean.
Monitoring Air Quality and Responding to Alerts
When smoke fills the air, knowing what’s actually in the air inside and outside your place helps you decide what to do next. Reliable monitoring lets you know when to seal up, filter the air, or just stay indoors and wait it out.
Using Air Quality Monitors and AQI Apps
An air quality monitor tracks pollutants like PM2.5, PM10, and sometimes gases such as carbon monoxide. Indoor monitors check changes inside your home, and outdoor monitors or public stations show local conditions.
A lot of folks use AQI (Air Quality Index) apps to check the air outside. These apps grab data from government and private networks. Some even show color-coded categories, for example:
| AQI Range | Category | Health Guidance |
|---|---|---|
| 0–50 | Good | No precautions needed |
| 51–100 | Moderate | Sensitive groups monitor |
| 101–150 | Unhealthy for SG | Limit outdoor exertion |
| 151–200 | Unhealthy | Stay indoors if possible |
| 201+ | Very Unhealthy+ | Avoid outdoor exposure |
If you pick a monitor with real-time readings and data logging, you can follow trends during a smoke event.
Interpreting Outdoor and Indoor Readings
Outdoor AQI values give you a sense of the air quality in your area, but your actual exposure depends on how much outside air gets into your home. When outdoor readings hit the unhealthy range, keep windows and doors closed.
Indoor readings can look very different. Even if the air outside is bad, a well-sealed home with good filtration can keep indoor PM2.5 much lower.
Compare indoor and outdoor values to see if your efforts are working. If indoor PM2.5 climbs even with filtration running, you might have leaks or unfiltered air sneaking in somewhere.
Timing Protective Measures
Protective actions work best if you take them before the air quality goes downhill. If forecasts or AQI alerts warn about unhealthy conditions, seal gaps, start air purifiers, and adjust HVAC systems early to help keep smoke out.
During smoky days when things change fast, check readings a few times a day. If outdoor AQI improves into the moderate range, you might get away with opening windows briefly without letting in too much pollution.
Jumping on alerts—like pausing outdoor activities or switching HVAC to recirculation—can help you avoid extra exposure and keep your indoor air healthier.
Protecting Vulnerable Groups and Special Considerations
Smoke can affect people in different ways depending on age, health, and activity level. Folks with weaker immune systems or preexisting conditions face higher health risks and need extra precautions to avoid exposure indoors.
Safeguarding Children and the Elderly
Kids breathe more air for their size than adults, so they take in more airborne pollutants. Their lungs are still growing, which makes them more sensitive to the fine stuff in smoke.
Older adults might have less lung capacity and weaker immune systems. Conditions like heart disease can get worse during poor air quality events.
Key steps include:
- Keep them inside a well-sealed, filtered space.
- Use a portable HEPA air cleaner in main living areas.
Try to limit physical activity so breathing rates stay low.
If going outside is necessary, keep it short and use well-fitted masks that filter particles. Caregivers should watch for coughing, shortness of breath, or unusual tiredness.
Managing Asthma and Respiratory Conditions
People with asthma, chronic bronchitis, COPD, or other breathing problems have a higher risk from smoke. Even small amounts of fine particles can trigger symptoms or flare-ups.
They should keep rescue inhalers or medications close by. Doctors usually recommend following an asthma action plan during smoke events.
Practical measures:
- Keep windows and doors shut.
- Use HVAC systems with efficient filters (MERV 13 or higher if it fits your system).
Don’t vacuum unless your machine has a HEPA filter, since regular vacuums just stir up particles.
A good air quality sensor indoors can show when filtration works. If symptoms get worse, seek medical help right away.
Guidance for Pets and Sensitive Individuals
Pets, especially animals with small lungs like birds or those with respiratory problems, can react to smoke too. You might notice them coughing, sneezing, or having irritated eyes.
Keep pets indoors in the cleanest part of your home. Make sure they have fresh water and don’t let them exercise much during smoke events.
Sensitive people, like those with weak immune systems or heart disease, should follow the same precautions. Using clean air rooms, skipping strenuous activity, and keeping indoor humidity between 30–50% can help with irritation and make breathing a bit easier.
For both pets and people, sudden trouble breathing is a medical emergency.
Additional Tips for Maintaining Indoor Air Quality
To cut down on smoke risks indoors, control pollutant sources, manage airflow, keep surfaces clear of ash, and use masks if needed. Small, steady habits can go a long way during smoky times.
Limiting Indoor Pollutant Sources
Indoor activities add to the smoke that’s already coming in. Smoking, burning candles, and using fireplaces all release fine particles and VOCs that make air worse.
Gas stoves and some cleaning products also release pollutants. If you can, switch to electric cooking and low-VOC cleaners during smoke events to cut down on extra emissions.
Don’t vacuum unless you’ve got a HEPA filter, since regular vacuums just kick up dust and ash. Cutting out these sources keeps the air cleaner and easier to filter.
Proper Use of Ventilation and Exhaust Fans
Ventilation needs to change during smoke events. Opening windows or using swamp coolers can bring in more smoke and ash.
Keep windows closed and seal up gaps around doors. Use exhaust fans in kitchens and bathrooms only if they vent outside and the air outside is actually clean.
If you have a central HVAC system, pop in a high-efficiency filter that’s rated for fine particles. Some systems use UV lights to help reduce airborne stuff, but honestly, those are just supplemental.
Cleaning Surfaces and Reducing Ash
Ash and smoke particles settle on floors, furniture, and other surfaces. Use damp microfiber cloths or mops to grab and remove fine particles instead of spreading them around.
Don’t dry sweep, since that just puts ash back into the air. Wash bedding, curtains, and other fabrics that can trap particles.
For electronics and delicate surfaces, use a soft, barely damp cloth to keep static from attracting ash. Regular cleaning during and after smoke events really cuts down on the particles that could get airborne again.
Using Masks When Necessary
Sometimes, you just can’t avoid going outside when the air quality takes a dive. If that’s the case, wearing the right mask can really help cut down your exposure to fine particles. N95 respirator masks, KN95 masks, or others with similar filtration usually do the best job at blocking smoke particles.
Make sure your mask fits snugly over your nose and mouth—no gaps. Honestly, surgical masks or cloth masks just don’t cut it for filtering out those tiny smoke particles.
If you need to reuse a mask, toss it in a breathable paper bag between uses. Swap it out if it gets dirty, damp, or starts feeling hard to breathe through. Sometimes, using a mask is your last line of defense when nothing else seems to work.