Inclusion criteria:
* Age 18-35 years old healthy male and female.
* No concerning findings on electrocardiogram (ECG) and no history of serious heart arrythmia.
* Normal lung function based on current American Thoracic Society(ATS) criteria.
* Forced vital capacity (FVC) 80% of that predicted for age, gender and height.
* Forced expiratory volume in one second (FEV1) 80% of that predicted for age, gender and height.
* FEV1/FVC absolute ratio of at least 70%.
* Oxygen saturation normal (94%) at the time of physical exam.
Exclusion criteria:
* A history of acute or chronic cardiovascular disease, chronic respiratory disease, a history of hospitalization for COVID-19, diabetes, rheumatologic diseases, immunodeficiency state.
* Active asthma or a history of asthma within the past ten years (by spirometry, medication use
* and/or symptoms).
* Allergy to chemical vapors or gases.
* Currently pregnant, attempting to become pregnant or breastfeeding.
* The use of high doses of vitamins and supplements, homeopathic/naturopathic medicines or medications (e.g., steroids, beta blockers) which may impact the results of the ozone challenge or interfere with any other medications potentially used in the study.
* Medications not specifically mentioned here will be reviewed by the investigators prior to a participant's inclusion in the study.
* Active smoker or smoking within the previous 2 years, or participants with a lifetime smoking
* history equivalent to 10 pack-years or greater. This includes vaping, hookah use and e-cigarette use.
* Uncontrolled hypertension (= 140 systolic, = 90 diastolic). Blood pressure readings equal to or greater that 140 Systolic and equal to or greater that 90 diastolic.
* Inability to communicate verbally in English.
* Unspecified illnesses or chronic conditions which, in the judgment of the investigators and EPA clinical staff, might increase the risk associated with ozone inhalation or affect the study outcome measurements.
* Individuals who will NOT comply with the following temporary exclusion criteria:
Temporary exclusion criteria:
* Individuals who have had an acute respiratory illness within 4 weeks.
* Individuals who have active allergic rhinitis and/or conjunctivitis.
* Individuals unable to avoid drinking alcohol for 24 hours prior to all study visits.
* Individuals who have been exposed to smoke and fumes for 24 hours before all visits.
* Individuals who have used an ozone-based home air purifier for 24 hours before all visits.
* Individuals who have consumed any food in the 2 hours prior to the consenting visit and follow up visit (contraindicated for sputum induction).
* Individuals should refrain from all over the counter anti-inflammatory agents (e.g., ibuprofen, aspirin, naproxen, acetaminophen) and antihistamines for allergies (e.g., cetirizine, diphenhydramine), and antioxidants for a period of one week prior to the consenting visit and to the exposure visits.
* Individuals who have been exposed to or have consumed any agent or have undertaken any recent activity in advance of any study visit that the investigators believe may compromise participant safety and/or study results.
* Individuals with a total symptom score greater than or equal to 20, or with more than one score equal to 3, with the exception of the symptom score for sweating.
* Failure to arrive at the medical station within 15 minutes of their scheduled visit time.
