Macrophage Regulation of Ozone-Induced Lung Inflammation (MOLI)

Inclusion Criteria: Individuals between 18-55 yrs. of age (No subject will be excluded from the study on the basis of gender or ethnicity) Individuals with knowledge of prior SARS-CoV-2 infection history allowing them to be segregated into one of three cohorts Cohort 1 - No history of SARS-CoV-2 infection (defined as no symptoms consisted with SARS-CoV-2 nor history of a positive SARS-CoV-2 test) Cohort 2 - Documented mild SARS-CoV-2 infection (a positive test, either PCR- or antigen-based) but with mild to no symptoms and no evidence of a lower respiratory tract infection (including no hospitalization, and no oxygen use) Cohort 3 - History of SARS-CoV-2 infection and symptoms/imaging consistent with a lower respiratory tract infection who have recovered, are >6 months out from their infection, and have normal lung function (spirometry with FVC, FEV1 and FEV1/FVC) There will be no maximal period from SARS-CoV-2 infection for inclusion in the study, the minimal period will be >6 months out from infection Exclusion Criteria: Individuals with prior SARS-CoV-2 pneumonia who have ongoing respiratory symptoms, are still using supplemental oxygen, or have abnormal lung function Individuals with prior SARS-CoV-2 infection that cannot provide documentation of a positive test Current smokers of tobacco products including e-cigarettes or those with previous smoking history within the prior 5 years Pregnant women and women who are presently lactating. Subjects that have received antibiotic administration or an upper respiratory infection within the previous 4 weeks College and graduate students or employees who are under direct supervision by any of the investigators in this protocol Alcohol or illicit substance abuse Chronic cardio/pulmonary respiratory disorders or other medical conditions as determined by the investigator Increased airway hyperresponsiveness at baseline as measured by a positive methacholine challenge response (methacholine PC20 FEV1 < 4 mg/ml) Subjects will be requested to refrain from antihistamines, nonsteroidal anti-inflammatory agents, antioxidants (e.g. beta-carotene, selenium, and lutein) and supplemental vitamins (e.g. C and E), for 1 week prior to, and during testing.