Wipe Sampling for Nicotine as a Marker of Thirdhand Tobacco Smoke Contamination on Surfaces in Homes, Cars, and Hotels

Introduction: Secondhand smoke contains a mixture of pollutants that can persist in air, dust, and on surfaces for months or longer. This persistent residue is known as thirdhand smoke (THS). Here, we detail a simple method of wipe sampling for nicotine as a marker of accumulated THS on surfaces. Methods: We analyzed findings from 5 real-world studies to investigate the performance of wipe sampling for nicotine on surfaces in homes, cars, and hotels in relation to smoking behavior and smoking restrictions. Results: The intraclass correlation coefficient for side-by-side samples was 0.91 (95% CI: 0.87-0.94). Wipe sampling for nicotine reliably distinguished between private homes, private cars, rental cars, and hotels with and without smoking bans and was significantly positively correlated with other measures of tobacco smoke contamination such as air and dust nicotine. The sensitivity and specificity of possible threshold values (0.1, 1, and 10 mu g/m(2)) were evaluated for distinguishing between nonsmoking and smoking environments. Sensitivity was highest at a threshold of 0.1 mu g/m(2), with 74%-100% of smoker environments showing nicotine levels above threshold. Specificity was highest at a threshold of 10 mu g/m(2), with 81%-100% of nonsmoker environments showing nicotine levels below threshold. The optimal threshold will depend on the desired balance of sensitivity and specificity and on the types of smoking and nonsmoking environments. Conclusions: Surface wipe sampling for nicotine is a reliable, valid, and relatively simple collection method to quantify THS contamination on surfaces across a wide range of field settings and to distinguish between nonsmoking and smoking environments.