Inclusion Criteria:  Being screened for lung cancer on LUCAS; At high-risk for lung cancer based on USPSTF guidelines: Asymptomatic adults aged 50-80 years Tobacco smoking history of at least 20 pack-years (one pack-year = smoking one pack per day for one year; 1 pack = 20 cigarettes) Current smoker or has quit smoking within the past 15 years. No history of lung cancer or any other active cancer within 3 years (Note: DCIS, CIN, non-invasive bladder cancer, non-melanomatous skin cancers are an exception); Ability to provide a breath sample; Ability to give informed consent.  Exclusion Criteria:  Persons who cannot give informed consent or assent (i.e. mentally incompetent persons, or those physically incapacitated) or do not have a legally acceptable representative are not to be recruited into this study; Persons who require the use of supplemental oxygen; The breath sampling technology is sensitive to the chemicals produced by tobacco, cannabis, and e-cigarettes as well as alcohol (consumed by the subject or used by the operator around the equipment). So we ask that subjects refrain from Smoking (tobacco, cannabis, or e-cigarettes ) at least 4 hours before and consuming alcohol (including mouthwash) 8 hours before breath sampling