Table 2.
Annual percentage change in GM benzene exposure overall, by sampling duration and within job groups. Unadjusted models and models adjusted for the variables design of process area (open, partially restricted, restricted), season (summer, winter), wind speed (three categories), and sampling duration (60–940 min). In addition, ‘All measurements’ were adjusted for job group (five groups).
| Unadjusted | Adjusted | ||
|---|---|---|---|
| Number of measurements | Annual percent change in GM (95% CI) | Annual percent change in GM (95% CI) | |
| All measurements | 924 | 12.1 (6.4–18.1) | 7.6 (2.9–12.5) |
| Measurements ≥ 480 min | 696 | 7.9 (2.7–13.3) | 9.2 (4.0–14.8) |
| Measurements < 480 min | 228 | −2.0 (−12.0 to 9.2) | 0.9 (−9.4 to 12.3) |
| Laboratory technicians | 102 | −8.5 (−17.3 to 1.2) | −12.6 (−20.0 to −4.8) |
| Measurements ≥ 480 min | 79 | −8.0 (−17.8 to 2.9) | −11.2 (−18.4 to 2.11) |
| Measurements < 480 min | 23 | −4.8 (−24.4 to 19.8) | −14.0 (−32.4 to −9.1) |
| Mechanics | 279 | 10.9 (1.4–21.3) | 8.6 (1.0–16.7) |
| Measurements ≥ 480 min | 198 | 19.9 (9.8–31.0) | 16.8 (6.7–27.7) |
| Measurements < 480 min | 80 | −13.4 (−30.7 to 8.2) | 3.8 (−10.1 to 19.8) |
| Process operators | 353 | 10.9 (2.6–20.0) | 6.0 (−1.6 to 14.2) |
| Measurements ≥ 480 min | 323 | 5.4 (−2.2 to 13.6) | 4.2 (−3.1 to 12.1) |
| Measurements < 480 min | 30 | 5.6 (−23.1 to 45.1) | 1.2 (−23.5 to 34.0) |
| Others | 135 | 16.0 (−4 to 40.2) | 13.0 (1.8–27.0) |