Macrophage Regulation of Ozone-Induced Lung Inflammation

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 respiratory viral infection history allowing them to be segregated into one of three cohorts

  * Cohort 1 - No history of respiratory viral infection (defined as no symptoms consistent with respiratory viral infection nor history of a positive respiratory viral test)
  * Cohort 2 - Documented mild respiratory viral 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 respiratory viral 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 respiratory viral infection for inclusion in the study, the minimal period will be \>6 months out from infection

Exclusion Criteria:

* Individuals with prior respiratory viral pneumonia who have ongoing respiratory symptoms, are still using supplemental oxygen, or have abnormal lung function
* 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.