Table 1

Participant characteristics

Participant characteristicsAll
P value
Demographics and anthropometrics
 Age (years)53.8±11.347.1±11.858.9±7.7<0.001
 Female sex (n (%))213 (86.9)25 (23.6)7 (5.0)<0.001
 Height (cm)166.3±7.1167.6±8.6165.4±5.50.046
 Weight (kg)66.3±11.566.9±12.365.8±11.00.754
 BMI (kg/m2)23.9±3.623.7±3.324.1±3.90.733
 Haemoglobin (g/dL)14.2±1.314.3±1.414.1±1.20.640
 Smoking history (pack-years) (min–max)0–30–30–10.811
 History of hypertension (n (%))11 (4.5)5 (4.7)6 (4.3)0.989
SHS exposure
 Ever cabin SHS exposure (n (%))139 (56.7)0 (0)139 (100)<0.001
  Cabin SHS exposure among exposed (years)9.3±10.70±016.6±9.1<0.001
  Time since last cabin SHS exposure (years)17.3±6.9--17.3±6.9NA
 Any form of non-cabin SHS exposure (n (%))245 (100)106 (100)139 (100)<0.001
  Childhood home SHS exposure (n (%))116 (47.3)41 (38.7)75 (54.0)0.059
  Adult home SHS exposure (n (%))59 (24.1)17 (16.0)42 (30.2)0.036
  Non-airline occupational SHS exposure (n (%))72 (29.4)23 (21.7)49 (35.3)0.069
  Other SHS exposure (n (%))111 (45.3)46 (43.4)65 (46.8)0.872
 mMRC Dyspnoea Scale ≥1 (n (%))25 (10.2)11 (10.4)14 (10.1)0.997
 Participants with any respiratory symptoms (n (%))112 (45.7)47 (44.3)65 (46.8)0.931
  Participants ever experiencing shortness of breath (n (%))29 (11.8)6 (5.7)23 (16.5)0.032
  Participants with cough ≥2 episodes/year (n (%))103 (42.0)45 (42.5)58 (41.7)0.994
  Participants with less activity than peers (n (%))5 (2.0)1 (0.9)4 (2.9)0.570
Pulmonary function tests
 FEV1 (% predicted)103±12104±12102±130.194
 FVC (% predicted)107±13109±14106±130.300
 FEV1/FVC (% predicted)95±696±695±60.784
 FEF25–75 (% predicted)94±2595±2394±270.915
 FEF75 (% predicted)112±44112±42112±450.999
 DLCO adjusted for Hgb (% predicted)81±1182±1079±110.169
 DL/VA adjusted for Hgb (% predicted)123±16121±18125±150.190
 Alveolar volume (VA) (L) (% predicted)95±1297±1394±110.133
 TLC (% predicted)103±11104±11103±110.888
 RV (% predicted)96±1894±1997±170.470
 RV/TLC (% predicted)90±1388±1491±110.165
 FRC (% predicted)103±20103±20103±200.999
 FRC/TLC (% predicted)99±1399±1398±140.966
  • Demographics, secondhand smoke (SHS) exposure, symptoms and lung function in participants with preserved spirometry that underwent exercise testing. Other SHS exposure was defined as non-aircraft cabin SHS exposure outside the work or home environment such as in recreational public places. Data are presented as mean±SD or number of participants with positive value for the variable (n) out of the total number of participants (N) and percentage of participants (%). Reference equations: per cent predicted of normal values of spirometry, diffusing capacity and lung volumes were calculated using Global Lung Function Initiative, Crapo et al and Quanjer et al predicted formulas, respectively.18–20 45

  • BMI, body mass index; DcoSB, single-breath diffusing capacity of carbon monoxide; FEF75, maximum airflow at low-lung volume; FEF25–75, maximum airflow at mid-lung volume; FEV1, forced expiratory volume in 1 s; FRC, functional residual capacity; FVC, forced vital capacity; Hgb, haemoglobin; mMRC, modified medical research council; RV, residual volume; TLC, total lung capacity.