The Effects of Positive Airway Pressure on the Mucolytic Effects of NAC (TEAM)

The goal of this clinical trial is to determine if positive pressure during inspiration will improve penetration of aerosolized N-Acetylcysteine (NAC) into airway mucus plugs in the lungs of patients with asthma or Chronic Obstructive Pulmonary Disease (COPD). The main questions it aims to answer are: * Does delivery of aerosolized NAC with positive inspiratory pressure have a greater effect on mucus plug burden in the lungs than delivery of NAC without positive pressure. * Does delivery of aerosolized NAC with positive inspiratory pressure have a greater effect on lung function than delivery of NAC without positive pressure. Participants will be assigned (in a single blind design) to the NAC via jet nebulizer group or the NAC via AeroEclipse-VersaPAP nebulizer group. Participants will each complete 5 treatment visits over the course of 30 days. Each treatment visit will consist of two treatments of a 10% NAC (3 mL) and 2.5 mg albuterol (0.5mL) inhalation solution separated by 4 hours, via the nebulization method specific to their group.