Why Smoke Smell Lingers

Check insulation, duct interiors, closets, the backs of cabinets and soft furnishings. Filters may need changing several times. See smoke damage cleanup.

Smoke smell lingers because smoke is not only a gas. It is a mix of fine particles, oily residues and chemical vapors that settle on and soak into everything they reach. Those deposits keep giving off odor long after the air has cleared, so the smell comes back once a window is shut or the room warms up.

Opening windows removes the odor that is in the air at that moment. It does not touch the source. That is why a room can seem fine after a breezy afternoon, then smell strongly the next morning. The only lasting fix is to remove the residue, or remove the materials holding it, and then deal with whatever is left.

What burned matters a great deal. A house fire involves plastics, wiring, foam, finishes and synthetic fabrics. A kitchen fire leaves greasy, sticky residue. Wildfire smoke may come from outside and travel through vents and gaps, even when there has been no flame in the house at all. Each one calls for its own approach, so a single product is unlikely to fix all of them.

Many people notice a smell that seemed to have gone returning on the first hot day. Warmth increases how quickly trapped vapors come out of materials, and humid air can make them easier for you to notice. Heating season has a similar effect: the first time a furnace runs after a fire, it can warm up dust and residue in the ducts.

Your own nose plays a part too. People get used to a smell within a short time, and then smell it again after a day away. A return from a trip is often when someone realizes that the problem was never solved. So trust the first impression you get on walking in, and ask someone who has not been living there what they notice.

If the smell gets stronger after rain or when the air conditioner runs, the source may be near a vent, in a damp area, or in a material that was wetted during firefighting. Smoke and moisture can be two problems in one location.

EPA is clear that ozone is a lung irritant, and that the ozone machines marketed as air cleaners pose health risks. The agency reports that ozone at safe levels has little ability to remove indoor pollutants, that it does not remove particles such as soot, and that its reactions can create irritating byproducts. Federal agencies have not cleared them for occupied rooms.

EPA also notes that high ozone levels may be used in some situations, including fire restoration, but only if people and pets are completely out of the space. Ozone can also damage rubber, fabric and other materials. Colorado's health department likewise advises the public to avoid air cleaners that produce ozone.

So don't buy an ozone machine for your bedroom. If a contractor proposes ozone, ask what cleaning will be done first, how long the space must remain empty, how it will be aired out afterward, and what materials could be affected. It should never be a stand-in for cleaning.

Your heating and cooling system pulls air from every room and passes it back through shared ducts. If smoke reached the return air during the fire, residue may be in the ducts, on the coil and in the air handler. Run the system and the odor travels with it, so a room with no visible soot can smell because of what comes out of its vent.

Colorado's health department suggests considering a MERV 11 or higher filter if your system can take it, and replacing filters as they clog or monthly for up to a year after the surrounding area is cleaned. It also suggests considering duct cleaning. Check with an HVAC technician before upgrading, because a denser filter can restrict airflow on some systems.

If the fire was significant, ask whether the system should run at all until it has been checked. A clean-up that ignores ducts tends to re-contaminate rooms that have just been cleaned. Keep a record of filter changes, since dirty filters soon after cleaning can tell you whether the source still exists.

Many belongings can be rescued, but the order matters. Remove them from the smell first, because a clean item put back in a smoky room will pick the smell back up. Contractors often clean contents off-site or in a separate clean area, then store them until the house has been finished.

For clothes, wash or dry-clean according to the care label, and do not dry anything in a machine until you are sure the odor has gone, since heat can make it harder to shift. Items with heavy soot should be shaken out outdoors or vacuumed first, wearing a mask, since water can drive soot into fibers. Consider a specialist for wedding dresses, leather, furs, antiques and artwork.

Electronics are worth a separate word. Soot can be corrosive and can settle inside devices. Keep them unplugged until someone has checked them. Papers and photos may need conservation advice if they are irreplaceable, and it is worth photographing or scanning them as soon as you can. A sensible rule of thumb: start with what cannot be replaced.

Don't treat a smell as just an annoyance if people feel unwell. Lingering smoke residue may contain irritating chemicals, and exposure can bother the eyes, nose and throat. People with asthma, heart disease or lung disease, along with children and older adults, are most likely to feel the effects. For labored breathing, chest pain or other severe symptoms, seek medical care. Mention the fire to a doctor.

A strong odor may also be a sign that a material is still off-gassing or that a fire-damaged item was missed. If symptoms improve when you leave the house, take that seriously. Staying with family or asking your insurer about temporary housing may be appropriate while the source is dealt with. The first 24 hours guide has more on that part of the process.

A burnt pot of food can create one of the most stubborn odors of all. Protein smoke can leave a thin, nearly invisible film on cabinets, walls and appliances. People often believe that a kitchen fire was too small to matter, since no walls burned, then spend months trying to get rid of a sour, sharp smell.

The cleaning method makes a difference. Because the film is hard to see, it's easy to miss the insides of cabinets, the tops of door frames, light fixtures and range hoods. Grease can also hold the smell, so filters and fan housings have to be cleaned or replaced. If a home-cleaning attempt has not fixed the smell after one careful pass, ask for advice, as repeatedly wiping surfaces without the proper product may smear the residue instead of removing it.