Clinical characteristics of 226 aluminium plant workers
| Potroom workers n=186 | Controls n=40 | |
| Age (y, mean (range)) | 40 (24–63) | 46 (25–60) |
| Duration of employment (y, mean (range)) | 16 (3–38) | 23 (4–40) |
| Smoking (n (%)): | ||
| Non-smokers | 99 (53) | 30 (75) |
| Current smokers | 87 (47) | 10 (25) |
| Asthma-like symptoms (n (%)) | 31 (17) | 5 (12) |
| Drugs inhaled (n (%)): | ||
| β2 agonists | 20 (11) | 3 (7) |
| Corticosteroids | 0 | 0 |