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.

Usually most people begin the process of purification by cleaning the largest surface areas such as ceilings, walls and floors. Some excellent odor and stain reducing cleaners such as HydroxiPro contain hydrogen peroxide, orange oil and surfactants. Left on the wall for 10 minutes, hydrogen peroxide will kill most biological organisms such as mold and mildew and will leave a clean fresh surface. Also, paint doesn’t stick too well to nicotine residue. Therefore, cleaning it well will greatly improve adhesion.

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.

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.

There are now more potent types of air purifiers such as Aranizers that generate molecules from O4 up to O19 which quickly purifies any environment. These molecules literally seek out or attack pollutants in the atmosphere.

What makes this process so different from normal filter type air purification is that there are no filters, and the scale of the particles is so small they get into every possible crevice. The oxidation process takes place quickly inside walls, closets and crawl spaces, carpet, upholstery and most porous walls. And all without filters!

Is it dangerous for humans? While there are those that do not like the smell of ozone and some that do, it is very effective at eradicating odors permanently. Because these machines are powerful, anyone who is chemically sensitive has heart or lung conditions should use them when away from the home. Like any powerful tools or equipment, exercising good judgment is always important. For serious remediation, we recommend hiring professionals.

This procedure requires the application of a topical sealer to a wall, ceiling or floor which creates a film that traps the odor and/or the stain inside. Most paints and primers are topical sealers but they don’t encapsulate very well because they are so porous. That means the film they create allows moisture or gases to penetrate or escape. Latex flat paints are highly porous, oil primers such as alkyds are less porous, oil enamels less and oil-based stain blockers and shellac are the least porous and thereby create the tightest film.

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. However, there is one company, AFM Safecoat that makes non-toxic water-based sealers, paints and primers that are specifically designed to encapsulate odors. While they may not work as effectively at stain blocking as their toxic counterparts, they block odors extremely well and produce no harmful off-gassing of their own. Sometimes two or even three coats are required depending upon the strength of the odor.

We've been selling AFM Safecoat for the past 15 years and have found that in most cases their Transitional Primer and Zero VOC paint blocks stains and seals in off-gassing with one to two coats. They also make clear encapsulating sealers such as AFM SafeCoat Hard Seal and AcriGlaze that can be applied directly over your existing paint. They won't affect the color of your existing paint but they will add a slight sheen.

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 and Hardseal are both designed to block off-gassing of formaldehyde. You could use either of these on your subfloor if you experience off-gassing when you remove your existing flooring.

How about encapsulating stains and odors in carpet or fabric? Again, AFM offers a three part system that is a cleaner and sealer of fibers and sealer of carpet backing all in one.