Baseline demographic, anthropometric and spirometry characteristics of study participants: normal subjects and electronic cigarette (e-cig) users
| Normal subjects# | E-cig users# | |
| Subjects | 26 | 22 |
| Age years | ||
| Overall | 33.88±14.07 | 35.54±12.21 |
| Male | 37.27±14.22 | 32.00±14.50 |
| Female | 31.40±13.91 | 38.50±9.58 |
| Sex | ||
| Male | 11 (42.3) | 10 (45.5) |
| Female | 15 (57.7) | 12 (54.5) |
| BMI kg·m−2 | 24.86±5.06 | 27.39±5.39 |
| Ethnicity | ||
| White | 18 (69.2) | 11 (50.0) |
| African-American | 3 (11.5) | 6 (27.3) |
| Asian | 4 (15.4) | 3 (13.6) |
| Hispanic | 1 (3.9) | 2 (9.1) |
| E-cig vaping status | ||
| Vaping duration years | 2.00±1.64 | |
| Vaping frequency day−1 | 7.75±3.14 | |
| Vaping session min | 8.79±5.50 | |
| Lung function variables | ||
| FEV1 % pred | 98.08±12.72 | 91.22±10.46 |
| FVC % | 99.17±11.69 | 95.72±13.20 |
| FEV1/FVC % | 99.26±6.12 | 95.50±8.98 |
| PEF % pred | 84.56±18.48 | 76.90±19.82 |
Data are presented as n, mean±sd or n (%). BMI: body mass index; FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; PEF: peak expiratory flow. #: not all biological samples collected from normal subjects and e-cig users were used for each biomarker analysis.