Small opacity profusion and progressive massive fibrosis among participants in the NIOSH Coal Workers' X-ray Surveillance Program, 1980–2008
| Year | Small opacity profusion category | Large opacity | |||
| 0 | 1 | 2 | 3 | PMF | |
| 1980–1989 (n=46928) | 45437 (96.8) | 1303 (2.8) | 168 (0.36) | 20 (0.04) | 68 (0.14) |
| 1990–1999 (n=15564) | 15100 (97.0) | 402 (2.6) | 55 (0.35) | 7 (0.04) | 21 (0.13) |
| 2000–2008 (n=28481) | 27568 (96.8) | 754 (2.7) | 130 (0.46) | 29 (0.10) | 91 (0.32) |
Data are numbers (%). PMF includes category A, B and C opacities.
NIOSH, National Institute for Occupational Safety and Health; PMF, progressive massive fibrosis.