Multiple Breath Washout (MBW) Using Sulfur Hexafluoride Reference Values and Influence of Anthropometric Parameters

Inclusion Criteria: non-smoker * no history of pulmonary disease * absence of dyspnoea, cough, thoracic pain * no self-reported smoking history * normal lung function testing * normal shape of flow-volume curve * normal shape of flow-pressure curve * FEV1/FVC \>70% (forced expiratory volume in 1 second / forced vital capacity) * TLC \> 80% of predicted (total lung capacity) * TLCO/VA \> 80% of predicted (transfer factor corrected for ventilated alveolar volume) * R5 \< 150% of predicted (resistance at 5Hz, impulse oscillometry) smoker \- as above, but with self-reported smoking history \>10 pack years Exclusion Criteria: * unwilling or unable to give informed consent * history of any respiratory disease