Q: What is the safest primer to use to get rid of tobacco smells in a home? We have been advised to use KILZ Original on the subflooring after ripping up our carpet and if that doesn't work to get rid of the smell, we were told to use KILZ on the walls. We have small children and don't want to expose them to something harmful.
—asked by Sarah Davis, Junction, IL

A: Eradicating smoke from cigarettes (or fires) in a building is one of the most challenging tasks on earth because it’s so ubiquitous and tenacious. Second or third-hand tobacco smoke leaves nasty nicotine residues in and on all porous and non-porous surfaces and spreads a noxious odor that affects one’s lungs for months or years unless properly abated.

If someone has smoked in a home for a long time, the smell of tobacco becomes deeply ingrained in the fabric of carpet, upholstery, wood, plaster or painted drywall. It also stains most hard surfaces in a way that makes simple cleaning an exercise in futility.

Because of its pervasiveness and penetration into porous surfaces, smoke remediation usually requires deep professional cleaning. Professionals use air purification, strong cleaning agents and encapsulation techniques. This can be very expensive and not always safe. For example, the cleaners that are sometimes used contain a variety of caustic and questionable chemicals which clean well but negatively affect your indoor air quality.

Below are some safe and relatively inexpensive ways you can eliminate smoke damage and improve the indoor air quality of your home.

Most air purification is done through micro-particle filtration, HEPA filters, granulated activated carbon adsorption and chemisorption. These are technical names for different types of filters that draw in particles, dust, pollen, pet dander, mold spores, VOCs, cigarette smoke, bacteria and viruses. Each type of filter removes or destroys harmful chemicals and biological pollutants usually down to the .3 micron level or larger. New HyperHEPA filters such as IQAir have been tested down to the .003 micron level which is the smallest particles that exist. These air purifiers (of which there are hundreds to choose from) do an excellent job of removing airborne particulates and cleaning the ambient air.

NOTE: We no longer offer IQAir machines, but instead are pleased to offer Austin Air Systems Air Purifiers, check out the HealthMate Plus.

BUT, an air purifier must draw the air into the filter in order to remove or destroy the pollutant. While most air purifiers have powerful motors that draw in air from all around the home, they have a hard time pulling air from inside crawl spaces, attics, closets, carpets, upholstery, plaster and other porous surfaces where pollutants, such as smoke, often lodge themselves for years.

Ozonation is another powerful method of air purification that works through a process called oxidation. They create particles of O3 which are unstable, but as they settle into their stable state of O2, they give off an electron that attaches itself to any particle floating in the air. Stated simply, this process causes particles of dust, pollen, mold spores, smoke, etc. to simply fall to the ground and die where they are cleaned up with a vacuum cleaner.

There are special ozone houses in some cities, for example, where you can take your clothing and furniture that has been exposed to smoke damage. They put them into a special controlled environment and blast them with high levels of ozone which eradicates the odor once and for all. Many organizations and governments have banned the use of ozone machines because of their potential damage to the lungs. The American Medical Association has likewise expressed extreme caution about using these types of air purification systems even though everyone seems to agree that they work effectively to remove smoke and other odors.

In general, oil based primers (and shellac) are good "stain blockers" that will keep the nicotine from leaching through and yellowing the surface. Unfortunately, most of these also contain mineral spirits and naphtha which are toxic solvents that off-gas strong odors making them counterproductive in terms of indoor air quality. Stain blockers don’t always mean odor blockers.

You mentioned KILZ. There seems to be many conflicting views expressed on the internet about how this product seals but some say any Alkyd primer or oil based primer will do the job just as well.

In general, water-based primers and paints are not as good at encapsulating nicotine stains because the nicotine is water soluble and it bleeds through.

Regarding your hard surface flooring, cleaning with hydrogen peroxide works well but if you are removing the flooring, you may have plywood underneath that still contains formaldehyde. AFM Safecoat Safeseal is designed to block off-gassing of formaldehyde. You could use this on your subfloor if you experience off-gassing when you remove your existing flooring.