Table 1 Main characteristics of the study population
| Low exposure a | High exposure b | p value (χ 2 test) | |
|---|---|---|---|
| Number (%) | 37 (63.8) | 21 (36.2) | |
| Exposure thoracic dust fraction (mg/m3) | 0.15 | 1.81 | |
| Age (mean; yrs) | 47.5 | 45.4 | |
| Age class | |||
| < 40 years | 16 (57.1) | 12 (42.9) | 0.31 |
| > 40 years | 21 (70.0) | 3 (30.0) | |
| Work seniority | |||
| < 10 years | 27 (57.4) | 20 (42.6) | 0.04 |
| > 10 years | 10 (90.9) | 1 (9.1) | |
| Smokers (%) | |||
| Yes | 15 (57.7) | 11 (42.3) | 0.38 |
| Not | 22 (68.7) | 10 (31.3) | |