TABLE 4.

The predicted percentage and estimated number of workers exposed to silica at least 10 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
Poured concrete foundation and structure contractors	238110	39	5300	2.87	1.06–4.67
Commercial and institutional building construction	236220	37	2800	0.56	0.16–0.96
Masonry contractors	238140	157	2700	2.15	1.24–3.06
Painting and wall covering contractors	238320	31	1100	0.64	0.13–1.15
Highway, street, and bridge construction	237310	97	900	0.34	0.13–0.55
All other specialty trade contractors	238990	54	900	0.41	0.13–0.70
Ready-mix concrete manufacturing	327320	41	800	1.19	0.24–2.14
Other heavy and civil engineering construction	237990	22	500	0.62	0.10–1.14
All other nonmetallic mineral product manufacturing	327990	268	400	0.73	0.44–1.01
Ferrous metal foundries	331510	490	200	0.24	0.17–0.32
Coating, engraving, heat treating, and allied activities	332810	78	200	0.13	0.05–0.20
Glass and glass product manufacturing	327210	56	100	0.07	0.01–0.14
Other concrete product manufacturing	327390	127	100	0.16	0.05–0.28
Plate work and fabricated structural product manufacturing	332310	60	100	0.05	0.02–0.07
			16 100

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.