Several clinical procedures have been described as aerosol generating procedure (AGP), including nebulization, high-flow nasal cannula oxygen therapy, noninvasive ventilation, and bronchial hygiene treatment, etc. However, the understanding on the transmission risk of these treatments is still unclear, particularly the methods to reduce the airborne particulate concentrations during these treatments are still lacking. This study is aimed to compare different modalities in reducing airborne particulate concentrations during these aerosol generating procedures, in order to find the most effective method to reduce particle concentrations, ultimately to decrease the transmission risk and protect health care providers.

Inclusion Criteria:

• Ages 18-65, Male or Female

Exclusion Criteria:

• Chronic lung disease, including asthma, COPD, etc.
• Upper airway anatomical abnormities
• Pregnancy
• Uncontrolled Diabetes, hypertension, or untreated thyroid disease
• Has any of the following symptoms in the last 21 days: sore throat, cough, chills, body aches for unknown reasons, shortness of breath for unknown reasons, loss of smell, loss of taste, fever at or greater than 100 degrees Fahrenheit.
• COVID-19 test positive within 21 days.

individual participant data would not be shared