| Uniform job category | Mean PCM fibre concentration (fibres >5 µm/cm3) (95% CI) | ||
| 1930–44 | 1945–64 | 1965–75 | |
| A, General area personnel | 26.2 (12.1 to 40.2) | 8.1 (6.0 to 10.1) | 5.8 (4.4 to 7.2) |
| B, Machine operators | |||
| Fly machine operator | 78.0 (38.1 to 117.8) | 23.9 (17.7 to 30.2) | 17.2 (13.1 to 21.3) |
| Crusher operator | 78.0 (38.1 to 117.8) | 23.9 (17.7 to 30.2) | 17.2 (13.1 to 21.3) |
| Waste machine operator | 45.9 (21.0 to 70.8) | 14.1 (9.5 to 18.7) | 10.1 (4.4 to 19.6) |
| C, Cleanup personnel | 54.4 (10.7 to 98.1) | 16.7 (5.4 to 28.0) | 12.0 (4.4 to 19.6) |
| D, Raw fibre handling | 35.0 (17.0 to 53.0) | 10.8 (7.3 to 14.2) | 7.3 (5.7 to 9.0) |