INTRODUCTION The present work examined the effect of passive exposure to electronic-cigarette (e-cigarette) emissions on respiratory mechanics and exhaled inflammatory biomarkers. METHODS A cross-over experimental study was conducted with 40 healthy nonsmokers, 18-35 years old with normal physical examination and spirometry, with body mass index < 30 kg/m(2), who were exposed to e-cigarette emissions produced by a smoker, according to a standardized protocol based on two resistance settings, 0.5 ohm and 1.5 ohm, for e-cigarette use. All participants underwent a 30-minute control (no emissions) and two experimental sessions (0.5 and 1.5 ohm exposure) in a 35 m(3) room. The following Impulse Oscillometry (IOS) parameters were measured at pre and post sessions: impedance, resistance, reactance, resonant frequency (fres), frequency dependence of resistance (fdr=R5-R20), reactance area (AX), and fractional exhaled nitric oxide (FeNO). Differences between pre and post measurements were compared using t-tests and Wilcoxon signed rank tests, while analysis of variance (ANOVA) was used for comparisons between experimental sessions (registered under ClinicalTrials.gov ID: NCT03102684). RESULTS IOS and FeNO parameters showed no significant changes during the control session. For IOS during the 1.5 ohm exposure session, fres increased significantly from 11.38 Hz at baseline to 12.16 Hz post exposure (p=0.047). FeNO decreased significantly from 24.16 ppb at baseline to 22.35 ppb post exposure in the 0.5 ohm session (p=0.006). CONCLUSIONS A 30-minute passive exposure to e-cigarette emissions revealed immediate alterations in respiratory mechanics and exhaled biomarkers, expressed as increased fres and reduced FeNO.