Study to Characterize the Durability of Hypertonic Saline to Enhance Mucociliary Clearance in Healthy Subjects

The purpose of this research study is to learn about how long hypertonic saline (HS) works in healthy subjects. Inhaled hypertonic saline is one of the medications used to treat Cystic Fibrosis (CF). In CF and more common lung diseases like chronic bronchitis, mucus builds up in the lungs. Hypertonic saline and other medications currently being developed may help patients with these lung diseases by speeding up mucus clearance from the lung. For these treatments to be effective, they likely need to be able to act for at lease several hours. Investigators are able to measure how lung treatments like hypertonic saline work by conducting a Mucociliary Clearance (MCC) scan. Currently, the investigators do not know how long hypertonic saline works in people who do not have CF. Investigators plan to use this information to improve the design and testing of new treatments for patients with chronic bronchitis. Objectives: 1. The investigators will use MCC measurements to determine the durability of action of hypertonic saline in healthy (i.e. non-CF) subjects. 2. The investigators will determine the intra- and inter-individual variability of baseline MCC measurements using a slow inhalation/large particle protocol in healthy subjects to guide future sample size calculations.