Table 4

Summary of historical and contemporary measurements of total dust (personal samples) and tremolite asbestos (stationary samples) 1969–96 at companies A and B, respectively, by department and occupation

Company A				Company B
Department/ job task				Total dust			Tremolite asbestos		Department/ job task		Total dust			Tremolite asbestos
Department/ job task				n	GM (mg/m³)^4-150		Range (mg/m³)	n	Department/ job task		Maximum (fibres/ml)^4-151	n		GM (mg/m³)^4-150	Range (mg/m³)	n	Maximum (fibres/ml)
Underground mine:						Open cast mine:
Drilling	6	2.9	1.0–59		2	<0.03	Drilling	11	12.5	0.2–78		1	<0.03
Charging	9	10.9	3.4–68			—	Loading	3	0.6	0.3–2.1		1	<0.03
Loading	4	2.5	1.1–3.5		1	0.06	Lorry driving	2	0.2	0.1–0.3		1	<0.03
Mixed		6.0^4-153				—
Mill:							Mill:
Manual sorting	18	20.4	2.8–56		2	0.10	Manual sorting	6	11.8	1.9–55		2	0.04
Crushing	12	21.4	2.2–83		1	<0.03	Crushing	6	5.9	2.9–10		1	<0.03
Bagging	32	20.7	2.5–136		4	0.12	Bagging	9	21.7	5.0–55		3	0.14
Truck driving	2	1.0	0.7–1.5		1	<0.03	Truck driving	3	3.9	3.1–4.9		1	0.05
Service		9.2^4-152				—	Service		6.0^4-152				—
Mixed		18.3^4-153				—	Mixed		10.1^4-153				—
Other		1.0^4-152				—	Other	2	1.1	0.9–1.4		1	<0.03
Lime works:							Lime works:
Mixing	42	9.6	0.5–36		3	<0.03	Mixing	14	8.0	1.7–17		3	0.03
Bagging	21	13.2	2.9–72		2	0.03	Truck driving	2	2.3	1.2–4.6		1	<0.03
Truck driving	2	0.4	0.4–0.5		1	<0.03	Mixed		5.7^4-153				—
Mixed		7.9^4-153				—	Other		1.1^4-152				—
Other		0.4^4-152				—
Putty works:							Putty works:
Mixing	14	6.0	2.4–16		5	0.03	Mixing	8	3.6	1.2–11		4	0.03
Truck driving	2	1.3	0.9–1.8		1	<0.03	Truck driving	2	0.9	0.7–1.2		1	<0.03
Mixed		4.6^4-153				—	Mixed		2.7^4-153				—
Other		1.3^4-152				—	Other		1.1^4-152				—
Total	158				23		Total	68				20

↵4-150 Geometric mean.
↵4-151 Maximum values; all samples collected in 1996; aspect ratio ⩾5:1.
↵4-152 Estimate.
↵4-153 Weighted geometric mean (for details, see text).
—No data.