Pack-year

The pack year, english pack year ( py), is the unit in which statistical or medical publications in the inhaled smoke dose of a cigarette smoker is described. From this, the number of cigarettes consumed estimate. This dose is critical for the risk, for example, a lung cancer or chronic obstructive pulmonary disease ( COPD ) develop.

The daily number of cigarettes smoked packs ( content about 20 pieces ) is multiplied by the number of years of smoking. For example, a smoker smokes two packs of cigarettes for four years on the day, thus (2 ⋅ 4 ) give eight pack-years. The inhalation depth or pollutant content of the cigarettes smoked as additional risk factors are not considered in this calculation.

In clinical practice, a mere distinction in those who never smoked, ex- smokers and smokers is performed instead of the calculation of pack-years.