Smoking history (according to the Textbook of pulmonary disease, 5th Edn, 199419)
| Age when the patient started to smoke |
| How old was the patient when he/she became a regular smoker? |
| Duration of smoking |
| Were there periods when the patient stopped smoking? |
| Is the patient currently smoking? |
| At what age did the patient stop smoking? |
| Amount smoked |
| Average lifetime number of cigarettes smoked per day. |
| Average lifetime number of cigars smoked per day. |
| Average lifetime amount of pipe tobacco smoked per day. |
| Packs-years of cigarettes smoked (average packs/day×number of years as a smoker). |