Pack Year

**Semantic type:** Quantitative Concept

**Definition:** A quantification of lifetime tobacco exposure defined as (number of cigarettes smoked per day x number of years smoked)/20. One pack-year is smoking 20 cigarettes a day for one year.

**Synonyms:** - Pack Year: The number of cigarettes smoked per day times the number of years smoked divided by 20 (the number of cigarettes in a pack) - Pack-Year - Smoking Pack Years - pack year - pack years smoked - pack_years_smoked - {Pack Year} - {Pack Year}