Getting Smoke Odor Out of a Home, and Why Ozone Is Risky

Why Smoke Smell Hangs On

Smoke is not just a smell. It is a cloud of tiny particles and oily compounds that land on every surface and soak into anything porous. Drywall, paint, carpet, upholstery, clothing, wood, insulation and the inside of your ductwork all hold onto it. As long as that residue is there, the odor will keep coming back, especially on warm or humid days when it releases more.

That is why air fresheners, scented candles and odor sprays fail. They add a stronger smell on top for a few hours. Real odor removal follows a simple order.

1. Get the air moving and filtered.
2. Remove residue from hard surfaces.
3. Wash or professionally clean fabrics.
4. Clean or replace what the HVAC system holds.
5. Seal the few surfaces that still smell after cleaning.
6. Deodorize what is left with safe, passive methods.

The type of fire matters too. Burned plastics and synthetics leave a sticky, smeary residue with a sharp smell. Kitchen protein fires leave a nearly invisible film with one of the worst odors of all. Wood and paper fires leave a dry, powdery soot that is easier to clean.

Air It Out and Filter It

Fresh air and filtration do not remove odor from surfaces, but they stop you from breathing particles while you work and they speed things up.

• Open windows on opposite sides of the home when the outdoor air is clean. Put a box fan in one window blowing out to pull air through.
• Run a HEPA air purifier in the room you are working in. Pick one rated for the room’s size or larger.
• Replace the furnace or air handler filter with a MERV 11 to MERV 13 filter before you run the system, then replace it again when cleaning is done. Check it weekly for the first month.
• If the fire was bad enough to coat the ducts, keep the system off until they are cleaned.

During wildfire smoke events, keep windows closed instead and rely on filtration. Outdoor air is the problem then, not the fix.

Clean Hard Surfaces From the Top Down

Start at the ceiling and work down to the floor so dirty drips land on areas you have not cleaned yet. If you see visible soot, dry clean it first with a HEPA vacuum and a dry chemical soot sponge before any water touches it. Wet cleaning soot before it is dry cleaned smears it into the paint.

For the wash step, use a degreasing cleaner or a trisodium phosphate substitute mixed per the label in warm water. Use two buckets, one with cleaning solution and one with clean rinse water. Wring the sponge well so you are damp wiping, not soaking the drywall. Do the ceiling first. On each wall, many pros wash from the bottom up, because a drip running down wet, clean paint wipes away easily while a drip on dry, dirty paint leaves a streak.

• Wash walls, ceilings, trim, doors, cabinets inside and out, and closet shelves.
• Clean window glass, blinds, screens and tracks. Blinds often hold a lot of smoke.
• Wipe light fixtures, fan blades, the tops of doors and the insides of drawers.
• Change rinse water as soon as it looks gray.

Rinse with clean water and let surfaces dry fully. Then smell them the next day with the windows closed. Anything that still smells gets a second wash or goes on the list to seal.

Fabrics, Carpet and Furniture

Soft goods hold the most odor. Treat them early, because the longer smoke sits in fabric the harder it is to remove.

Do not put smoky clothes in a hot dryer until they smell clean. Heat can lock the odor into the fibers. Check each load before drying.

Seal What Cleaning Cannot Fix

Some drywall, wood framing, subfloor and unfinished surfaces will still smell after a good washing. The residue is inside the material. At that point the fix is to seal it with an odor-blocking primer, then paint.

• Choose a pigmented shellac based or alcohol based stain and odor blocking primer. These are the types most often used after fires. Some water based primers are labeled for odor blocking but are generally considered less reliable for heavy smoke.
• Clean first. Primer over loose soot will peel and the odor can still bleed through.
• Ventilate well. Shellac primers have strong fumes. Wear a respirator rated for organic vapors if you are priming a whole room.
• In an attic or exposed framing after a fire, pros often clean or blast the wood and then seal it.

Paint alone does not stop smoke odor. Regular latex paint over smoky walls will look fine and still smell on the first hot day.

Why Ozone Generators Are Risky

Ozone generators are sold as odor killers and are cheap to rent or buy. They can work in the hands of a pro, but they are one of the riskiest tools a homeowner can use.

• Ozone is a lung irritant. It can cause coughing, chest tightness and shortness of breath, and it worsens asthma. The EPA’s guidance on ozone generators says that at levels safe for people, ozone does little to remove odors or pollutants, and at levels high enough to work, it is harmful to breathe.
• High ozone levels can damage rubber, some plastics, fabrics and artwork over time.
• Ozone does not remove the residue. If soot is still on the walls, the smell often returns.
• Ozone reacts with some household chemicals and can create new irritating byproducts.

Professionals who use ozone run it only in an empty, closed building, with every person, pet and houseplant out. Then they turn it off and air the home out before anyone returns. Never run an ozone generator in an occupied space, and never sleep in a room where one has been running. Hydroxyl generators are a slower alternative that pros often use when people must stay nearby, and thermal fogging is another pro method.

The Hidden Places Smoke Hides

If you have cleaned everything you can see and the smell is still there, check these spots.

• Ductwork and the air handler. Smoke gets pulled into return ducts. Professional duct cleaning is often needed after a real fire.
• Inside kitchen and bath exhaust fans and range hoods.
• The attic and insulation. Smoke rises, and blown-in insulation can hold odor for years. Smoky insulation is usually removed and replaced.
• Inside wall cavities behind outlets and switch plates.
• Closets, especially clothes and boxes stored in them.
• Under the carpet in the pad.
• Inside appliances, including the fridge, oven, microwave, washer and dryer.

For the last lingering smell, open boxes of baking soda and bowls of activated charcoal in closets and cabinets help absorb odor. They are slow but completely safe.

Step by Step

1. Replace the HVAC Filter

   Put in a fresh MERV 11 to MERV 13 filter. If the ducts look sooty, leave the system off until they are cleaned.

2. Ventilate and Filter

   Open windows on opposite sides if the outdoor air is clean and run a HEPA purifier in the work room. Wear an N95 while you work.

3. Remove Loose Soot Dry

   HEPA vacuum and use a dry chemical sponge on any visible soot before any water touches the surface.

4. Wash Surfaces Top Down

   Using two buckets, wash ceilings, walls, trim, cabinets, blinds and fixtures with a degreasing cleaner. Rinse and let everything dry.

5. Launder and Clean Fabrics

   Wash clothes and bedding with detergent and baking soda and air dry. Send dry clean only items out and have carpet and upholstery professionally cleaned.

6. Do the Sniff Test

   Close the windows overnight and smell each room the next day. Mark any surface that still smells.

7. Seal Stubborn Surfaces

   Prime the marked surfaces with a shellac or alcohol based odor-blocking primer, then paint once it is dry.

8. Deodorize What Is Left

   Place baking soda and activated charcoal in closets and cabinets. Replace the HVAC filter again when you finish.

Mistakes That Make It Worse

• Painting over smoky walls with regular paint. The odor bleeds right through within weeks.
• Running an ozone generator while living in the home. It irritates the lungs and still leaves residue behind.
• Using air fresheners and scented candles as the fix. They only mask odor and add more chemicals to the air.
• Drying smoky clothes on high heat before the odor is gone. Heat can set the smell for good.
• Forgetting the ducts and filter. A dirty system spreads the smell back into clean rooms.

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