Having smoked at least  cigarette within  weeks of study enrollment
Having smoked at least one cigarette within  month of cancer diagnosis
Non-cigarette tobacco use in the past  days
Patient-reported cigarette use within the past  days
Currently a smoker, defined as self-reported cigarette smoking (some days, every day) within the past  days
Smokes first cigarette within  minutes after waking
Have working cigarette lighter receptacle/socket inside taxi cab
All participants must be nonsmokers at the time of the study (i.e., have not used any tobacco product); have not smoked an entire cigarette, cigar, or hookah session before
STUDY I: Current e-cigarette users who have successfully quit smoking
STUDY I: >=  month of e-cigarette use
STUDY II: Smoking at least one cigarette per week over the past year
STUDY I: Smoked at least one cigarette per week prior to undergoing the CT scan
STUDY II: Smoked at least one cigarette over the past week
No contraindications for e-cigarette use
Patients must be current smokers who smoke at least one cigarette most days per week, or recent quitters who smoked at least one cigarette most days per week (<  months); and
past six month use of any e-cigarette
lifetime ever purchase of any e-cigarette
use of non-cigarette tobacco products (e.g., cigarillos) in the last  days
daily (+ days within past ) cigarette smoker of > cigs/day