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<\/div>\nNovember 12 at 7:00 AM<\/span><\/p>\n<\/div>\n Q:\u00a0<\/b>I live in a second-floor condo unit. The woman who lived below me for around 10 years was a heavy smoker. I had a cigarette smell in my unit constantly, and although she moved away nearly 20 years ago, I can still smell it. It’s worse in my closets, and it still seeps into clothes stored in drawers. If it is spring or fall when the heat pump fan is not running often, I smell the lingering cigarette odor when I walk in. How can I eradicate this?<\/em><\/p>\n Alexandria<\/strong><\/p>\n A:<\/b>\u00a0Cigarette stink lingers long after the smoke has cleared because it penetrates into fabrics, water-based paint and other materials, but isn\u2019t locked in there. For many years, the smelly ingredients gradually seep back into the air or into other objects.<\/p>\n For years, the best advice was to clean or toss out everything absorbent and then to seal the walls, ceiling and floors. To get rid of any remaining odor, people could set out containers of charcoal or other odor-absorbing material. Then ozone treatment came along, and today it\u2019s the go-to solution offered by numerous companies that specialize in cleaning up after fires.<\/i><\/p>\n But there are some serious caveats about resorting to ozone, said Brian W. Christman, a professor of medicine at Vanderbilt University who volunteers as a national spokesman for the American Lung Association. \u201cOzone makes it hard for people with asthma or heart trouble, and at high enough levels, it can bother anyone,\u201d he said, noting that ozone is a key factor in air pollution.<\/p>\n And ozone is not an all-in-one solution, said Mike Calamus, owner of Calamus Enterprises (301-275-5640;\u00a0cigarette.odorremoval.us<\/a>\u00a0<\/i>), a company in Rockville that does ozone treatments throughout the Washington area. You have to clean up first. That means removing carpet and carpet pads and scrubbing everything, even the windows. And after the ozone treatment, you have to seal the walls and ceilings. Calamus recommends oil paint for that because it is a one-step solution, but you could instead prime with an oil- or shellac-based primer, and then recoat that with whatever paint you want. Using only a water-based paint won\u2019t work though.<\/p>\n The ozone treatment gets rid of the smelly bits you can\u2019t scrub away. With three oxygen atoms in each molecule, rather than the two oxygen atoms in the air we breathe, ozone is unstable, so its extra oxygen atom can detach and grab onto many other kinds of molecules. If the molecules are stinky ones, they can change to be non-smelly. But if the molecules are inside the lungs of a person or pet, the result can be lung damage, chest pain, coughing and shortness of breath.<\/p>\n Unfortunately, to effectively eliminate odor, the ozone concentration needs to be higher than what is considered safe to breathe, Christman said. The Environmental Protection Agency, which recommends against buying home air-filtering equipment that generates ozone, reviewed numerous\u00a0scientific studies<\/a>\u00a0and concluded that ozone concentrations that do not exceed public health standards have little likelihood of removing odors. But the EPA warned that concentrations high enough to work can cause damage to plants, rubber, electrical wire coatings, fabrics, and the dyes and pigments in some artwork, in addition to causing health problems.<\/p>\n Calamus agrees with the warnings. \u201cThis is a serious thing,\u201d he said. \u201cPeople can\u2019t be around. It would be like breathing bleach.\u201d He warns his customers to remove especially vulnerable items before the treatment. To prevent damage to the plastic coating on electrical wires, trained technicians run an ozone generator for only two to four hours at a setting that is safe for wiring. Then they leave the house closed for two full days, allowing the ozone molecules to do their work. The technicians air out the space before people and pets move back in.<\/p>\n The cost for ozone treatment starts at $600, which generally covers about 1,000 square feet, Calamus said. Numerous other factors can also affect the cost.<\/p>\n Could someone just skip the ozone treatment? \u201cNo,\u201d Calamus said. \u201cIt\u2019s what takes away that smell. The other things are just helping. If you don\u2019t do ozone, you still have the smell underneath the paint.\u201d But with ozone and the proper prep and follow-up steps, an odor problem can be cured \u201c99 percent of the time,\u201d he said. The exceptions he\u2019s seen involved basements with mildew and other issues.<\/p>\n