Imaging Sex Differences in Smoking-Induced Pulmonary Inflammation

1. Participants will be 18-45 years of age

2. Subject must meet one of the following criteria: NIC vapers: current e-cigarette use of nicotine at least 5 days per week for the past year, no current combustible cigarette use, cannabis vaping, or cannabis smoking during the 30 days prior to study enrollment CAN vapers: current e-cigarette use of cannabis at least 5 days per week for the past year, no current combustible cigarette use, cannabis smoking, or nicotine vaping during the 30 days prior to study enrollment Cigarette smokers: current cigarette smoking of at least 5 cigarettes per day, 4 days per week for the past year with no e-cigarette use (cannabis or nicotine) during the 30 days prior to study enrollment Dual combustible and e-cigarette users: current e-cigarette use of cannabis and/or nicotine at least 5 days per week for the past year with cigarette or cannabis smoking during the 30 day prior to study enrollment Non-Smokers: reported non-smoking history or < 100 lifetime cigarettes, < 100 e-cigarette use episodes, and < 100 lifetime cannabis use episodes

3. Participants must be informed of the investigational nature of this study and be willing to provide written informed consent and participate in this study in accordance with institutional and federal guidelines prior to study-specific procedures.

1. Females who are pregnant or breast feeding at the time of screening will not be eligible for this study; a urine pregnancy test will be performed in women of child-bearing potential at screening and on scan day.

2. Current untreated and unstable diagnosis of substance use disorder, except nicotine use disorder or cannabis use disorder

3. Positive urine drug screen for opiates, methamphetamine or cocaine at screening

4. Reported regular use of nicotine or cannabis products (except edibles) other than ENDS, cigarettes, or cannabis bowls, pipes, or blunts (e.g., smokeless tobacco, nicotine replacement therapy, wax, shatter, tinctures)

5. Current unstable and/or untreated major depression or psychotic disorder per medical record review or self-reported

6. Use of inhaled or oral corticosteroids or anti-inflammatory medications per medical record review or self-report

7. History of lung trauma

8. Active (or within the previous 4 weeks of screening) lung infection or lung disease that impact uptake of [18F]NOS (e.g. tuberculosis, cystic fibrosis)

9. Inability to tolerate imaging procedures in the opinion of an investigator or treating physician

10. Any current or past medical condition, illness, or disorder as assessed by medical record review and/or self-reported that is considered by a physician investigator to be a condition that could compromise participant safety or successful participation in the study