Table 3

Non-malignant chronic respiratory diseases (NMCRD) mortality trend by ILO categories and cumulative exposure to silica dust

ObservedSMR (95% CI)
ILO categories:
 1/0–1/2474.63 (3.57 to 5.99)
 2/1–2/3685.11 (4.13 to 6.33)
 3/2+1637.21 (6.33 to 8.22)
 χ2 Trend statistic9.56
p=0.008
Cumulative exposure to respirable silica (gh/m3):
 ⩽5.0475.07 (4.23 to 6.08)
 5.1–10.0686.08 (5.18 to 7.14)
 >10.01637.52 (6.16 to 9.19)
 χ2Trend statistic6.17
p=0.024