Table 2.

Measured personal ROC exposure levels (μg m⁻³) for underground, mixed, and surface workers by mining facility: full-shift time-weighted average concentrations

Mining facility	n	n < LOD	AM	GM	GSD
Underground
A	108	0	167	137	1.8
B	124	0	195	99	3.0
D	84	0	101	87	1.7
E	118	0	128	114	1.7
G	126	0	64	58	1.6
H	116	0	110	89	2.1
I	103	0	89	76	1.9
Mixed underground and surfacea
A	31	0	102	87	1.8
B	4	0	82	68	2.0
E	11	0	92	85	1.5
G	18	0	64	56	1.8
H	19	0	77	65	1.8
I	18	0	63	57	1.6
Surface
A	33	0	54	47	2.0
B	63	6	38	32	1.9
D	35	0	48	42	1.6
E	25	0	69	61	1.6
G	31	0	70	67	1.3
H	33	0	71	59	1.8
I	47	0	66	55	1.9

n, Number of measurements.

^aMixed workers spent time both underground and on the surface during the work shift monitored. No mixed workers were sampled at Facility D.