Primary Care

Pack-Years (Smoking)

Cumulative tobacco exposure.

Education and reference only. Not a substitute for clinical judgement, local policy or product labelling. Always verify before clinical use. Values are calculated in your browser and never stored.

When to use

Use to quantify smoking history, e.g. for lung-cancer screening eligibility and COPD risk assessment.

Why use

It standardises smoking burden for risk discussions and screening thresholds.

Critical actions

Pack-years = (cigarettes per day ÷ 20) × years smoked. Many lung-screening programmes use a ≥20 pack-year threshold.

Evidence & references

  1. Pack-years = (cigarettes/day ÷ 20) × years smoked.

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