Table 4.

Arithmetic mean (AM), geometric mean (GM), their standard deviations (ASD, GSD), and median of exposure measurements of crystalline silica (mg/m³) by occupation in the stonework masonry industry (SIC code 1741), IMIS (1988–2003).

Occupation	No.a	AM	ASD	GM	GSD	Median
Helper	6	0.175	0.198	0.099	1.143	0.050
Stone cutter	33	0.097	0.096	0.070	0.814	0.050
Bricklayer	30	0.091	0.086	0.067	0.742	0.050
Laborer	48	0.093	0.102	0.067	0.731	0.050
Masonry worker	74	0.088	0.090	0.065	0.713	0.050
Foreman	8	0.085	0.081	0.064	0.748	0.050
Tuckpointer	18	0.086	0.110	0.062	0.647	0.050
Grinder	35	0.055	0.020	0.052	0.372	0.050
Hod carrier	5	0.092	0.123	0.042	1.540	0.050
All	257	0.088	0.093	0.065	1.140	0.050

^aNumber of personal TWA sample measurements.