Third hand smoke is the combination of smoke pollutants and particles that remain in the indoor environment for months after the smoker has left the room. These pollutants are deposited on dust, furniture, rugs, and clothing and some interact with gases in the atmosphere to become even more toxic. Although the health effects of THS have not been nearly as well documented as those of second hand smoke, more data are now available that document this as a potential exposure of toxic tobacco generated chemicals.
In a fascinating study reported by Matt GE et al in the Tobacco Control Journal (2011 Jan;20(1), the homes of 100 smokers and 50 non-smokers were visited before the residents moved out. Dust, surfaces, air, and participants’ fingers were measured for nicotine and children’s urine samples were analyzed for cotinine (a metabolite of nicotine).
Although smokers dust inside their homes, surface and air nicotine levels decreased after they moved out, dust and surfaces showed a higher contamination level in former smoker homes than in former non-smoker homes. Non-smoking participant’s finger nicotine level was higher when they moved into former smoker homes compared to when they moved into former non-smoker homes.
THS accumulates in smokers’ homes and persists when smokers move out even after these homes remain vacant for two months even when they were cleaned and prepared for new residents. When non-smokers move into homes formerly occupied by smokers, they are exposed to environments with THS polluted surfaces and dust.