| 1991 | 2000 | |
| Total participants | 2633 | 1346 |
| Males, N (%) | 1312 (50%) | 667 (50) |
| Mean age (SD), years | 44.4 (13.6) | 46.3 (12.3) |
| Smoking status in 1991, N (%) | ||
| Never | 1306 (50) | 714 (53) |
| Ex | 730 (28) | 391 (29) |
| Current | 597 (23) | 241 (18) |
| Mean FEV1 in 1991(SD), l | 3.19 (0.92) | 3.18 (0.84) |
| Mean FVC in 1991 (SD), l | 3.94 (1.07) | 3.94 (1.00) |