Distribution (mean (SD)) of silicosis by stage and Chinese data on cumulative exposure to total dust (CTD))
| Stage | Silicosis | Exposure to CTD (mg/m3-y) | Age at first exposure* | Year of first exposure* |
| I | 509 | 87.7 (64.8) | 26.7 (7.2) | 1963 (8.2) |
| II | 378 | 110.2 (66.3) | 27.7 (7.7) | 1964 (9.5) |
| III | 128 | 126.3 (73.4) | 26.1 (7.6) | 1959 (12.8) |