Table 3.

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 gray iron foundry industry (SIC 3321), IMIS (1988–2003).

Occupation	No.a	AM	ASD	GM	GSD	Median
Spruer	22	0.232	0.182	0.154	0.100	0.205
Hunter operator	10	0.157	0.151	0.093	1.144	0.050
Charger	8	0.146	0.156	0.091	0.999	0.050
Core maker	89	0.129	0.135	0.078	1.033	0.050
Grinder	371	0.112	0.123	0.075	0.821	0.050
Molder	308	0.116	0.129	0.073	0.910	0.050
Abrasive blast operator	56	0.103	0.110	0.070	0.821	0.050
Sorter	23	0.098	0.108	0.067	0.827	0.050
Reline cupola	29	0.096	0.113	0.067	0.725	0.050
Furnace operator	47	0.096	0.110	0.066	0.766	0.050
Core setter	23	0.086	0.082	0.066	0.671	0.051
Craneman	16	0.097	0.106	0.066	0.815	0.050
Cleaning department	36	0.094	0.117	0.060	0.879	0.050
Inspector	21	0.118	0.146	0.057	1.298	0.050
Ladle repair	30	0.081	0.098	0.055	0.829	0.050

^aNumber of personal TWA sample measurements.