Cigarettes vs. e-cigarettes: Passive exposure at home measured by means of airborne marker and biomarkers

There is scarce evidence about passive exposure to the vapour released or exhaled from electronic cigarettes (e-cigarettes) under real conditions. The aim of this study is to characterise passive exposure to nicotine from e-cigarettes׳ vapour and conventional cigarettes׳ smoke at home among non-smokers under real-use conditions. We conducted an observational study with 54 non-smoker volunteers from different homes: 25 living at home with conventional smokers, 5 living with nicotine e-cigarette users, and 24 from control homes (not using conventional cigarettes neither e-cigarettes). We measured airborne nicotine at home and biomarkers (cotinine in saliva and urine). We calculated geometric mean (GM) and geometric standard deviations (GSD). We also performed ANOVA and Student׳s t tests for the log-transformed data. We used Bonferroni-corrected t-tests to control the family error rate for multiple comparisons at 5%. The GMs of airborne nicotine were 0.74μg/m3 (GSD=4.05) in the smokers’ homes, 0.13μg/m3 (GSD=2.4) in the e-cigarettes users’ homes, and 0.02μg/m3 (GSD=3.51) in the control homes. The GMs of salivary cotinine were 0.38ng/ml (GSD=2.34) in the smokers’ homes, 0.19ng/ml (GSD=2.17) in the e-cigarettes users’ homes, and 0.07ng/ml (GSD=1.79) in the control homes. Salivary cotinine concentrations of the non-smokers exposed to e-cigarette׳s vapour at home (all exposed ≥2h/day) were statistically significant different that those found in non-smokers exposed to second-hand smoke ≥2h/day and in non-smokers from control homes. The airborne markers were statistically higher in conventional cigarette homes than in e-cigarettes homes (5.7 times higher). However, concentrations of both biomarkers among non-smokers exposed to conventional cigarettes and e-cigarettes’ vapour were statistically similar (only 2 and 1.4 times higher, respectively). The levels of airborne nicotine and cotinine concentrations in the homes with e-cigarette users were higher than control homes (differences statistically significant). Our results show that non-smokers passively exposed to e-cigarettes absorb nicotine. •This is the first study of e-cigarette exposure at home under real-use conditions.•Airborne nicotine in homes with smokers were 5.7 times higher than in e-cig homes.•Cotinine of non-smokers exposed to e-cig and conventional cigarettes was similar.•Airborne nicotine in homes with e-cig users was higher than control homes.•Cotinine of non-smokers exposed to e-cig users was hig