Characteristics of the study population
| Total | Ever smokers | Never smokers | Men | Women | |
| No of participants | 3343 | 1934 | 1409 | 1638 | 1705 |
| Person-years of follow-up | 66 854 | 38 648 | 28 207 | 32 709 | 34 145 |
| Mean follow-up and range (years) | 20.0 (18.0–22.4) | 20.0 (18.0–22.4) | 20.0 (18.2–22.1) | 20.0 (18.0–22.3) | 20.0 (18.2–22.4) |
| No of incident COPD cases | 96 | 79 | 17 | 51 | 45 |
| COPD incidence per 1000 person-years | 1.4 | 2.0 | 0.6 | 1.6 | 1.3 |
| % men | 49.0 | 51.7 | 45.4 | – | – |
| Mean age at baseline (years) | 34.2 | 34.7 | 33.5 | 34.3 | 34.0 |
| Mean lifetime pack-years of smoking at follow-up | 10.6 | 20.6 | – | 13.3 | 7.9 |
| % current asthma at follow-up | 8.1 | 8.4 | 7.7 | 6.2 | 10.0 |
| % of participants exposed (low or high) | |||||
| Biological dust | 32.3 | 32.5 | 32.0 | 30.0 | 34.4 |
| Mineral dust | 25.2 | 28.1 | 21.2 | 36.7 | 14.1 |
| Gases and fumes | 43.5 | 45.8 | 40.4 | 51.7 | 35.7 |
| Vapours, gases, dusts and fumes | 48.4 | 50.1 | 46.1 | 56.4 | 40.7 |
| Herbicides | 2.2 | 2.1 | 2.4 | 3.2 | 1.3 |
| Insecticides | 3.4 | 3.5 | 3.3 | 4.9 | 1.9 |
| Fungicides | 3.9 | 4.2 | 3.5 | 6.3 | 1.7 |
| All pesticides | 4.9 | 5.4 | 4.3 | 7.7 | 2.2 |
| Aromatic solvents | 16.4 | 17.1 | 15.4 | 26.7 | 6.4 |
| Chlorinated solvents | 13.1 | 14.2 | 11.7 | 21.1 | 5.5 |
| Other solvents | 28.5 | 27.8 | 29.4 | 32.1 | 25.0 |
| Metals | 12.6 | 13.6 | 11.2 | 22.9 | 2.7 |