A screening visit will be conducted within 4 weeks prior to admission to the investigational site. The 8-day confinement period consists of the admission day (Day1), 1 day ad-libitum smoking (Day0), 3 days of smoking abstinence (Day1-3), 2-day exposure period smoking 2 and 4 cigarettes (Day4-5), and the day of discharge (Day6) followed by a 7-day safety follow-up period. Urine collection will be performed for each subject from Day0 to Day5 in 4 intervals.