Health
Pack Year
A unit measuring cumulative tobacco exposure. One pack year = smoking one pack (20 cigarettes) per day for one year. A 30-pack-year history significantly increases lung cancer and COPD risk.
Pack-years give clinicians a single number to summarize cumulative tobacco exposure regardless of when someone smoked. Thresholds such as a 20- or 30-pack-year history help determine eligibility for lung-cancer screening.
Key Formula & Relationship
Pack-Years = Packs per Day × Years Smoked
Reviewed by the Calculover Editorial Team for mathematical and practical accuracy.
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