The purpose of the study is to better understand the mechanisms of lung injury from ozone exposure. Subjects will participate in two exposure sessions: filtered air and 0.2 ppm ozone. The exposure visits will be at least 2 weeks apart. Subjects will be asked to produce sputum through coughing after each exposure. The samples will be analyzed for macrophage activity.

Subjects will be asked to come to the Rutgers EOHSI clinical center (Piscataway, NJ) for 5 study visits. A physical exam to determine eligibility will be done at the first study visit. If the subject is healthy and able to produce a sputum sample, he/she will then be scheduled for 2 3-hour exposure visits, at least 2 weeks apart. One exposure will be to clean air and the other exposure will be to 0.2 ppm ozone. During the exposures, subjects will be requested to ride an exercise bicycle intermittently (approximately every 15 minutes). A follow-up visit for sputum collection will be scheduled either 24, 48, or 72 hours after each exposure visit. Blood and exhaled breath samples will also be collected at each visit.

Exclusion Criteria:

• Cardiovascular disease
• Respiratory disease
• Recent (within 4 weeks) respiratory or COVID-19 symptoms
• Diabetes
• Pregnancy
• HIV Infection
• History of smoking within the past 5 years.
• Orthopedic or rheumatologic conditions which would interfere with cycle use
• Inability to produce a sputum plug at screening
• Daily use of antioxidant supplements, excluding those in a multivitamin. These supplements include Vitamin C or E, selenium, beta-carotene, lycopene, lutein, zeaxanthin and ginkgo biloba. Supplements taken less frequently but at least once a week will be reviewed by the principal investigator for eligibility determination.

Subjects and laboratory personnel will not be informed of the type of exposure.