Potential participants will be prescreened by telephone and scheduled for a final eligibility visit that will include vital signs/anthropometry, medical/medication history review, physical exam, urine tests, blood draw, urine collection, and pulmonary function tests (PFTs; i.e., spirometry and methacholine challenge test). After eligibility is confirmed, the participant will be scheduled for a baseline visit, which includes vital signs/anthropometry, medical/medication history review, physical exam, blood draw, urine collection, and bronchoscopy (with lavage and brushing). Participants will return 14-40 days between the baseline visit and study treatment visit, which includes vital signs/anthropometry, blood draw, urine collection, spirometry, one-time administration of ionic silver via nebulizer, and instructions to collect urine for 24 hours. The next day after the study treatment visit, the participant will return for a visit that includes vital signs/anthropometry, blood draw, providing the 24-hour urine sample, spirometry, and bronchoscopy. During each bronchoscopy procedure, bronchoalveolar lavage (BAL) fluid and tissue from bronchial brushings will be collected from the participant to obtain alveolar macrophages and bronchial epithelial cells.