Clinical characteristics of 212 tunnel workers and 205 outdoor construction workers
| Variable | Tunnel workers (n = 212) | Construction workers (n = 205) |
| Age (years)1-150 | 41 (10) | 40 (11) |
| Height (cm)1-150 | 180 (6) | 179 (6) |
| Years of employment1-150 | 13 (9) | 17 (9) |
| <10 years1-151 | 84 (40) | 48 (23) |
| 10–20 years1-151 | 95 (45) | 90 (44) |
| >20 years1-151 | 33 (15) | 67 (33) |
| Smoking status1-151 | ||
| Never smoked | 59 (28) | 64 (31) |
| Former smokers | 39 (18) | 34 (17) |
| Current smokers | 114 (54) | 107 (52) |
| Pack years1-150 | 16 (13) | 14 (10) |
| Phadiatop positive1-151 | 34 (16) | 27(13) |