TABLE 3.

The predicted percentage and estimated number of workers exposed to silica at least five times the NIOSH REL in 2014 by five-digit NAICS code^a

NAICS title	NAICS code	Number of inspections with silica samples after data editing	Estimated workers exposedb	Percentage exposedc	90% CIc
Residential building construction	236110	14	22 500	3.76	0.73–6.79
Poured concrete foundation and structure contractors	238110	39	6300	3.42	1.61–5.24
Masonry contractors	238140	157	4100	3.33	2.18–4.49
Commercial and institutional building construction	236220	37	4000	0.81	0.31–1.30
Painting and wall covering contractors	238320	31	2200	1.25	0.48–2.01
All other specialty trade contractors	238990	54	2100	0.97	0.46–1.48
Testing laboratories	541380	9	2000	1.52	0.09–2.95
Highway, street, and bridge construction	237310	97	1800	0.71	0.38–1.03
All other nonmetallic mineral product manufacturing	327990	268	1200	1.99	1.49–2.50
Ready-mix concrete manufacturing	327320	41	1000	1.43	0.36–2.50
Brick, stone, and related construction material merchant wholesalers	423320	18	1000	3.31	0.22–6.40
Other heavy and civil engineering construction	237990	22	800	1.00	0.32–1.68
Ferrous metal foundries	331510	490	400	0.59	0.47–0.72
Coating, engraving, heat treating, and allied activities	332810	78	300	0.22	0.12–0.33
Clay building materials and refractories manufacturing	327120	121	200	0.94	0.56–1.31
Pottery, ceramics, and plumbing fixture manufacturing	327110	71	100	0.79	0.40–1.18
Glass and glass product manufacturing	327210	56	100	0.10	0.04–0.16
Other concrete product manufacturing	327390	127	100	0.27	0.11–0.43
Nonferrous metal foundries	331520	208	100	0.10	0.05–0.15
Plate work and fabricated structural product manufacturing	332310	60	100	0.08	0.04–0.12
Mining and oil and gas field machinery manufacturing	333130	14	100	0.10	0.00–0.20
Pump and compressor manufacturing	333910	15	100	0.13	0.00–0.26
			50 600

Abbreviations: CI, confidence interval; NAICS, North American Industry Classification System; NIOSH, National Institute for Occupational Safety and Health; REL, recommended exposure limit.

^aThis does not account for respirator use.

^bRounded to the nearest 100 workers.

^cRounded to the nearest 100th percent.