A home's air may seem cleaner after a smoker has quit, but researchers report in the journal Tobacco Control that toxins from tobacco smoke can linger for months. "We tend to see smoke in the air and then it’s out of sight, out of mind," lead author Georg Matt of San Diego State University tells the New York Times. But because it leaves behind carcinogenic chemical compounds in dust and on surfaces ranging from carpet to wallpaper and ceiling tiles, he says, "No level of exposure to tobacco is safe." Researchers tested the homes of dozens of smokers who'd just quit and found that all residents were still exposed to thirdhand smoke pollutants in dust and on surfaces after six months.
While the level of toxins dropped significantly when the smoker quit, they were still detectable at the end of the study, and traces turned up in people's urine. The researchers say more research should follow on how to remove such pollutants more quickly. The study follows a report by Reuters that 24 million nonsmoking kids are exposed to secondhand smoke in the US thanks largely to their parents, which works out to four in 10 school-aged children. Last month, the American Heart Association reported that this exposure in childhood can lead to lifelong health problems and shorter life expectancy and urged "zero tolerance." (Some of the compounds found in thirdhand smoke are the most potent carcinogens.)