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| Characteristic | Value |
|---|---|
| Age of smoking initiation (years), mean (SD) | 17.5 (3.9) |
| Number of pack years, mean (SD) {range} | 20.0 (22.4) {<1.0–144} |
| Duration of smoking cessation for former smokers (n = 89) (years), mean (SD) | 14.2 (10.0) |
