TABLE 3—

Task-Based Silica Exposures: Sample Data

Task	No. of Samples	Range of Sample Results (mg/m3)a	Mean (mg/m3)a	SD	No. (%) of Samples Above OSHA PEL	No. (%) of Samples Above ACGIH TLV
Operating a jackhammer	25	0.03–0.63	0.276	0.161	22 (88)	24 (96)
Sawing concrete	6	0.15–0.50	0.348	0.144	6 (100)	6 (100)
Milling concrete	2	0.99–1.15	1.070	0.113	2 (100)	2 (100)
Cleaning up concrete	6	0.02–0.26	0.152	0.099	4 (67)	5 (83)
Milling asphalt	8	nd–0.07	0.041	0.027	0	4 (50)
Cleaning up asphalt	3	nd–0.02	0.007	0.012	0	0
Drilling dowels	2	0.05–0.16	0.107	0.076	2 (100)	2 (100)

Note. mg/m³ = milligrams of respirable dust per cubic meter of air; OSHA PEL = Occupational Safety and Health Administration permissible exposure limit; ACGIH TLV = American Conference of Industrial Hygienists threshold limit value; nd = nondetectable (below lower detection limit).

^a8-hour time-weighted-average samples.