Tobacco and cannabis smoke, and strong cooking smells, are two problems at once. The visible haze is fine particles, which a HEPA filter handles well. The smell is gases, which HEPA does not touch. A purifier that fixes one but not the other is the most common disappointment.
Particles: HEPA, sized up
Pick a true HEPA purifier with a high smoke CADR. Smoke is the hardest of the three CADR tests, so this is the number to compare. For a room where someone smokes, go well above the rule of thumb of two thirds of the floor area. See how to size a purifier.
Smell: it takes a lot of carbon
- Odor gases are captured by activated carbon. The more carbon, the longer it works. Purifiers built for odors hold several pounds of loose granular carbon; many popular models have a thin carbon-coated pre-filter that saturates within weeks.
- When the smell comes back while the purifier is running, the carbon is full. Replace it; carbon cannot be washed or recharged at home.
- Carbon helps with smell. It does not make smoke safe to breathe.
What a purifier cannot fix
Smoke leaves a residue on walls, carpet and fabric that keeps releasing odor for months, sometimes called thirdhand smoke. Air cleaning does not remove it; washing surfaces and fabrics, or replacing carpet, does. And the heating and ventilation engineers' society (ASHRAE) says ventilation and air cleaning cannot remove the health risk of secondhand smoke indoors. Only keeping smoke out does.
If it comes from a neighbor
- Find the path. In apartments, smoke travels through gaps around outlets, pipes, baseboards, ceiling fixtures and the front door. Foam outlet gaskets, caulk and a door sweep are cheap and often help more than a purifier.
- Bathroom and kitchen fans can pull air in from shared shafts or neighboring units when they run. Notice whether the smell gets worse with them on.
- Ask about the building's rules. Many buildings are smoke-free by lease, and HUD has banned smoking inside public housing units since 2018. Put the complaint in writing.
Cooking smells
A range hood that vents outside, run during and for a while after cooking, removes cooking smoke and odor at the source better than any purifier. Recirculating hoods only filter grease and some odor. A purifier with carbon helps with what is left over.
Skip these
- Ozone generators sold for odor. Ozone irritates the lungs at levels high enough to affect smells.
- Plug-in fresheners and candles add their own particles and chemicals on top of the smoke.
A PM2.5 air quality monitor shows when smoke gets in and whether your fixes worked, which is also useful evidence for a landlord.