Introduction:
The current study aimed to examine the effect of passive exposure to e-cigarette emissions on respiratory mechanics and exhaled inflammatory biomarkers. The study was part of the European project, “Tackling second hand tobacco smoke and e-cigarette emissions: exposure assessment, novel interventions, impact on lung diseases and economic burden in diverse European populations” (TackSHS Project, Work Package 6, ClinicalTrials.gov ID: NCT03102684).

Methods:
40 non-smokers, 18-35 years old, BMI<30, healthy with normal physical examination and Spirometry, were exposed to e-cigarette emissions produced by a human smoker according to a standardized protocol based on two resistance settings, 0.5 and 1.5 Ohm, for e-cigarette use. Non-smokers underwent a 30-minute Control (no emissions) and two Experimental (exposure 0.5 and 1.5) sessions, in a 35m3 room. Impulse Oscillometry (IOS) parameters Impedance, Resistance, Reactance, Resonant Frequency (fres), Frequency Dependence of Resistance (fdr=R5-R20) and Reactance Area (AX) as well as Fractional Exhaled Nitric Oxide (FeNO) were measured pre and post sessions. T-tests and Wilcoxon signed rank tests were used to compare differences between pre and post measurements and Analysis of Variance (ANOVA) for multiple comparisons between sessions.

Results:
IOS and FeNO parameters showed no significant changes during the Control session. For IOS during the exposure 1.5 session, fres increased significantly post exposure from 11.38 Hz to 12.16 Hz (p<0.05). FeNO decreased significantly from 24.16 ppb to 22.35 ppb immediately post exposure in the exposure 0.5 session (p=0.006).

Conclusions:
A 30-minute passive exposure to e-cigarette emissions revealed immediate alterations on respiratory mechanics and exhaled biomarkers expressed as increased fres and reduced FeNO.

Funding:
This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 681040.