Table 1.

Recommended exposure limits for respirable crystalline silica in occupational settings.

Agency	Description	Level
American Conference of Governmental Industrial Hygienists (AGCIH) [11]	Threshold Limit Value (TLV) Time Weighted Average (TWA)	0.025 mg/m3
National Institute for Occupational Safety and Health (NIOSH) [12]	Recommended Exposure Limit (REL)	0.050 mg/m3