Lung function tests are necessary at screening and must meet Inclusion Criteria #4 for the subject to qualify for the study. Previous lung function tests cannot be used. DLCO tests done within 12 months can be used, but the assessment can be waived if a subject is unable to complete it, for example due to coughing. Previous CT scans are expected to be used to check exclusion criterion #4 (‘Emphysema ≥50% on high-resolution computed tomography, or the extent of emphysema is greater than the extent of fibrosis according to the reported results of the most recent scan’).