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Table 2 Exposure characteristics of miners (n = 357)

From: The risk of pulmonary tuberculosis in underground copper miners in Zambia exposed to respirable silica: a cross-sectional study

Characteristics Mine 1 (n = 137) Mine 2 (n = 99) Mine 3 (n = 121)
Length of service, years, Mean (SD) (Range) 5.2 (2.7) (1.0–13.1) 5.0 (2.5) (1.1–11.4) 5.2 (2.3) (1.2–11.0)
Overall respirable silica dust mg/m3, Median (Range) 0.4 (0.0–1.0) 0.2 (0.1–1.3) 0.2 (0.1–0.5)
Silica dust in sections mg/m3, Median (Range)
 Crusher Attend 0.6 (0.1–1.0) 0.3 (0.1–0.9) 0.3 (0.1–0.5)
 Blasting Tech/Foreman 0.5 (0.2–0.9) 0.4 (0.1–1.1) 0.3 (0.1–0.4)
 Lasher 0.4 (0.0–1.0) 0.2 (0.1–1.0) 0.2 (0.1–0.4)
 Driller 0.4 (0.2–0.9) 0.2 (0.1–0.9) 0.2 (0.1–0.5)
 Trammer 0.4 (0.2–0.8) 0.3 (0.1–1.3) 0.2 (0.1–0.4)
 W/shop foreman/Attend 0.4 (0.1–0.7) 0.2 (0.1–0.6) 0.2 (0.1–0.4)
 Others-workman 0.4 (0.1–0.9) 0.2 (0.1–1.0) 0.2 (0.1–0.4)
Cumulative respirable silica dust mg.y/m3, Mean (SD) (Range) 1.3 (0.7) (0.3–3.2) 1.1 (0.5) (0.3–2.2) 2.3 (1.0) (0.7–4.7)
  1. SD Standard deviation, tech Technician, Attend attendant, W/shop workshop