Post-BD spirometry testing will be assessed at specified visits after the subject has performed pre-BD spirometry. Maximal bronchodilation will be induced using a SABA such as albuterol (90 μg metered dose) or salbutamol (100 μg metered dose) or equivalent with a spacer device for a maximum of 8 total puffs (Sorkness et al, 2008). The same number of puffs (ie, 4, 6, or 8 puffs) and post-BD maneuvers used at baseline (Visit 4, Week 0, Day 1) to identify the maximal post-BD FEV1 measurement, must be used each time post-BD spirometry testing is performed.