Measurement of airborne nicotine, as a marker of secondhand smoke exposure, in homes with residents who smoke in 9 European countries

Objective: Smoke-free policies are effective in preventing secondhand smoke (SHS) exposure, but their adoption at home remains largely voluntary. This study aimed to quantify SHS exposure in homes with residents who smoke in Europe according to households' characteristics, tobacco consumption habits, and national contextual factors.Methods: Cross-sectional study (March 2017-September 2018) based on measurements of air nicotine inside 162 homes with residents who smoke from nine European countries. We installed passive samplers for seven consecutive days to monitor nicotine concentrations. Through self-administered questionnaires, we collected sociodemographic information and the number of individuals who smoke, smoking rules, frequency, location, and quantity of tobacco use in households. Country-level factors included the overall score in the Tobacco Control Scale 2016, the smoking prevalence, and self-reported SHS exposure prevalence. Nicotine concentrations were analyzed as continuous and dichotomous variables, categorized based on the limit of quantification of 0.02 mu g/m3.Results: Overall, median nicotine concentration was 0.85 mu g/m3 (interquartile range (IQR):0.15-4.42), and there was nicotine presence in 93% of homes. Participants reported that smoking was not permitted in approximately 20% of households, 40% had two or more residents who smoked, and in 79% residents had smoked inside duringthe week of sampling. We found higher nicotine concentrations in homes: with smell of tobacco smoke inside (1.45 mu g/m3 IQR: 0.32-6.34), where smoking was allowed (1.60 mu g/m3 IQR: 0.68-7.63), with two or more residents who smoked (2.42 mu g/m3 IQR: 0.58-11.0), with more than 40 cigarettes smoked (2.92 mu g/m3 IQR: 0.97-10.61), and where two or more residents smoked inside (4.02 mu g/m3 IQR: 1.58-11.74). Household nicotine concentrations were significantly higher in countries with higher national smoking prevalence and self-reported SHS exposure prevalence (p < 0.05). Conclusions: SHS concentrations in homes with individuals who smoke were approximately twenty times higher in homes that allowed smoking compared to those reporting smoke-free household rules. Evidence-based interventions promoting smoke-free homes should be implemented in combination with strengthening other MPOWER measures.