Pack-Year (Cigarette Smoking)
Definition and examples Pack years are defined as follows: Number of pack-years = (number of packs smoked per day) x (years smoked). So, if 1 pack was smoked per day for 4 years, the number of pack-years = 4. A pack usually contains 20 cigarettes. If the number of cigarettes per day is known, the … Pack-Year (Cigarette Smoking)
