Smoking History (Pack-Years)

Smoke Pack Years is a measure of smoking exposure calculated by multiplying the number of cigarette packs smoked per day by the number of years the person has smoked. One pack-year is considered equivalent to smoking 20 cigarettes, the standard number in a pack, every day for a year. It is a common way to assess the long-term impact of smoking on health, particularly in studies related to lung health. [19] [21]

[19]Pleasants RA, Rivera MP, Tilley SL, Bhatt SP. Both Duration and Pack-Years of Tobacco Smoking Should Be Used for Clinical Practice and Research. Ann Am Thorac Soc. 2020;17(7):804-806. doi:10.1513/AnnalsATS.202002-133VP

[21]History of tobacco and health - MUSK - 2003 - Respirology - Wiley Online Library. Accessed November 6, 2025. https://onlinelibrary.wiley.com/doi/full/10.1046/j.1440-1843.2003.00483.x?sid=nlm%3Apubmed