Table 2.

Geometric mean (GM) and GSD of exposure measurements of crystalline silica (mg/m³) by industry and type of inspection, IMIS (1988–2003).

	All inspections (n = 2,512)				Programmed inspections (n = 948)
Industrya (SIC code)	No.b	GM	GSD	No.b	GM	GSD
Soap and other detergents (2841)	6	0.102	0.757	5	0.108	0.831
Testing laboratories services (8734)	53	0.099	0.896	19	0.082	0.656
Cut stone and stone products (3281)	405	0.091	0.956	164	0.075	0.963
General contractors (1541)	28	0.091	0.900	8	0.057	0.346
Coating engraving (3479)	75	0.075	0.839	26	0.072	0.842
Gray iron foundries (3321)	1,760	0.073	0.877	782	0.082	0.899
Concrete work (1771)	94	0.073	0.705	38	0.072	0.720
Manufacturing explosives (2891)	9	0.070	0.841	5	0.058	0.581
Bridge tunnel construction (1622)	91	0.070	0.827	41	0.069	0.761
Stonework masonry (1741)	274	0.065	0.732	111	0.063	0.803
All	7,209	0.073	0.919	2,868	0.077	0.935

^aThe industries where at least five samples were collected during inspections.

^bNumber of personal TWA sample measurements.