Reduction of Exposure, Inflammation, and Oxidative Stress Following at Least 2 Years of Switching to THS Use Compared to Cigarette Smoking

Inclusion Criteria: * Subject is able to understand the information provided in the main ICF and has signed the main ICF. * Subject is 30-60 years old. * Subject is healthy based on ECG, spirometry, vital signs, physical examination, medical history and Investigator's assessment. Cigarette smokers: * Has smoked ≥ 10 cigarettes/day on average (no brand restriction) over the past 2 years prior to screening. * Has smoked ≥ 10 cigarettes/day on average (no brand restriction) for at least 10 years. * Has not used other tobacco and nicotine products apart from cigarettes on a daily basis over the past 2 years prior to screening. * Smoking status will be verified by urinary cotinine test (≥ 200 ng/mL) and CO breath test (≥ 10 ppm (1)). THS users: * Has used ≥ 10 HeatSticks/day on average over the past 2 years prior to screening. * Has smoked ≥ 10 cigarettes/day on average (no brand restriction) for at least 8 years prior to switching to THS. * Has smoked \< 30 cigarettes/month and used other tobacco products or e-cigarettes \< daily over the past 2 years prior to screening. * Product use will be verified by urinary cotinine test (≥ 200 ng/mL) and CO breath test (\< 10 ppm). Former cigarette smokers: * Has not smoked cigarettes or used any tobacco or nicotine-containing products on a daily basis over the past 2 years prior to screening. * Has smoked ≥ 10 cigarettes/day on average (no brand restriction) for at least 8 years prior to stopping smoking. * Smoking status will be ve…