. 2008 Jun 30;5(2):86–90. doi: 10.3390/ijerph5020086

Table 3:

Occupational exposure limits (OELs) of dust and crystalline silica for US and Zambian institutions

Institution	Substance	Name of OEL	OEL value (mg/m³) or definition
OSHA, U.S.	Dust (respirable) containing quartz	Permissible exposure limit (PEL)	10/(SiO₂ %+2)
ACGIH, U.S.	Quartz Cristobalite Tridymite Crystalline silica	Threshold limit value (TLV)	0.025
NIOSH, U.S.	Quartz Cristobalite Tridymite Crystalline silica	Recommended exposure limit (REL)	0.05
MSHA, U.S.	Dust (respirable) containing >1% quartz in surface and underground metal and nonmetal mines	Threshold limit value (TLV)	10/(SiO₂ %+2)
MSD, Zambia	Dust	(legal limit)	1.75