Table 3– Definitions
BHRHistamine PD15 ≤1.6 mg
Marked BHRHistamine PD15 ≤0.4 mg
BHR severity [13]
 SeverePD15 ≤0.100 mg
 ModeratePD15 0.101– ≤0.400 mg
 MildPD15 0.401– ≤1.600 mg
 NonePD15 ≥1.601 mg
Normal FEV1≥80% pred
Normal FVC≥80% pred
Normal FEV1/FVC≥88% pred
Normal MEF50≥63% pred
Physician-diagnosed asthmaSubjects who answered “yes” to the question: “Have you been diagnosed as having asthma by a physician?”
Childhood wheezeSubjects who answered “yes” to the question: “Have you been diagnosed as having asthma or have you had wheeze in childhood?”
AtopyAt least one positive skin prick test reaction to any of the tested allergens or reported symptoms of allergic rhinoconjunctivitis
NonsmokerNever-smoker or smoking <4 cigarettes per month
Ex-smokerThose who had quit smoking ≥12 months prior to the study
Exposure to ETSThe subjects were asked three separate questions about ETS: “Have you ever been exposed to environmental tobacco smoke at home/at work/generally in the surroundings?” The answer alternatives of all three questions were: “never”, “yes previously, not any more” and “yes, currently”
ETS exposure everETS at home or at work, or both, currently or previously
ETS exposure presentETS currently at the time of the study at home, at work, or both
  • BHR: bronchial hyperresponsiveness; FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; MEF50: maximal expiratory flow at 50% of FVC [21]; ETS: environmental tobacco smoke; PD15: provocative dose of histamine inducing a 15% fall in FEV1; % pred: % predicted.