Demographics and lung function
| Miners | Controls | |
| Subjects n | 22 | 21 |
| Age yrs | 43 (30–59) | 40 (25–63) |
| Smoking habits n | ||
| Never-smoker | 10 | 20 |
| Ex-smokers | 12 | 1 |
| Mean working time underground yrs | 18 (3–39) | |
| FEV1 % pred normal | 105±11.6 | 109±11.4 |
| VC % pred normal | 101±9.9 | 106±10.2 |
| FEV % | 102±5.7 | 101±5.8 |
Data are presented as mean (range) and mean±sd, unless otherwise stated. FEV1: forced expiratory volume in one second; VC: vital capacity; FEV: FEV1/VC. All subjects were male.