Residual tobacco smoke in used cars: futile efforts and persistent pollutants.

INTRODUCTION: Smoking cigarettes in the enclosed environment of a car leads to the contamination of a car's microenvironment with residual tobacco smoke pollution (TSP).
METHODS: Surface wipe, air, and dust samples were collected in used cars sold by nonsmokers (n = 40) and smokers (n = 87) and analyzed for nicotine. Primary drivers were interviewed about smoking behavior and restrictions, and car interiors were inspected to investigate (a) differences in car dustiness, signs of past smoking, ventilation use, mileage, and passenger cabin volume among nonsmokers and smokers with and without in-car smoking bans and (b) factors that contribute to the contamination of cars with residual TSP, such as ventilation use, cleaning behaviors, signs of past smoking, and holding the cigarette near/outside the car window while smoking.
RESULTS: Smokers reported using air conditioning less (p < .05) and driving with windows down more often than nonsmokers (p = .05); their cars were also dustier (p < .01) and exhibited more ash and burn marks than nonsmokers' cars (p < .001). Number of cigarettes smoked by the primary driver was the strongest predictor of residual TSP indicators (R(2) = .10 - .16, p = .001). This relationship was neither mediated by ash or burn marks nor moderated by efforts to remove residual TSP from the vehicle (i.e., cleaning, ventilation) or attempts to prevent tobacco smoke pollutants from adsorbing while smoking (e.g., holding the cigarette near/outside window). DISCUSSION: Findings suggest that smokers can prevent their cars from becoming contaminated with residual TSP by reducing or ceasing smoking; however, commonly used cleaning and ventilation methods did not successfully decrease contamination levels. Disclosure requirements and smoke-free certifications could help protect buyers of used cars and empower them to request nonsmoking environments or a discount on cars that have been smoked in previously.