Note: This table only includes occupational exposure limits (OELs) for substances listed in the OSHA Z-3 Table. OELs for hundreds of additional substances have been adopted by Cal/OSHA, NIOSH, and ACGIH. These organizations periodically make revisions to their OELs and so they should be consulted directly for their most current values and substances, as well as special notations such as for skin absorption. The TLVs® and BEIs® are copyrighted by ACGIH® and are not publicly available. However, they can be purchased in their entirety on the ACGIH® website at http://www.acgih.org/store/. Permission must be requested from ACGIH® to reproduce the TLVs® and BEIs®. Click here for permission request form.
|Regulatory Limits||Recommended Limits|
|OSHA PEL(b)||Cal/OSHA PEL(c)
(as of 4/26/13)
Up to 10-hour TWA
(as of 4/26/13)
|ACGIH® 2015 TLV®(e)
|Silica: Crystalline||0.025 (resp.) for α-quartz and cristobalite|
See Appendix A
|Quartz (Total Dust)||30 mg/m3||0.3|
|Cristobalite||Use ½ the value calculated from the count or mass formulae for quartz.||0.05 (resp.)||Ca
See Appendix A
|0.025 (resp.) for α-quartz and cristobalite|
|Tridymite||Use ½ the value calculated from the formulae for quartz.||0.05 (resp.)||Ca
See Appendix A
|See TLV® book Appendix G|
|Amorphous, including natural diatomaceous earth||20||80 mg/m3
|6||See TLV® book Appendix G|
|Silicates (less than 1% crystalline silica):|
|Mica||20||3 (resp.)||3 (resp.)||3 (resp.)|
|Talc (not containing asbestos)||20(i)||2 (resp.)||2 (resp.)||2 (resp., < 1% crystalline silica)|
|Talc (containing asbestos)||Use asbestos limit||See Section 5208||Use asbestos limit
|Use asbestos TLV®|
|Tremolite, asbestiform||See 29 CFR 1910.1001||See Appendix A
See Appendix C
|Portland cement||50||See PNOR||10 (total)
|1 (resp., < 1% crystalliine silica and no asbestos)|
|Graphite (Natural)||15||2.5 (resp.)||2.5 (resp.)||2 (resp., natural, all forms except fibers)|
See Appendix C
|0.9 (resp.) bituminous or lignite; 0.4 (resp.) anthracite (Note coal dust should also be monitored for crystalline silica and if present, see TLV® book Appendix E for mixtures)|
|Respirable fraction less than 5% SiO2||2.4 mg/m3 (k)||0.9 (bituminous)|
|Respirable fraction greater than 5% SiO2||10 mg/m3(k)||0.1 (bituminous)|
|Inert or Nuisance Dust: (j)||See TLV® Book Appendix B|
|Respirable fraction||15||5 mg/m3||5 (See PNOR)||See Appendix D|
|Total Dust||50||15 mg/m3||10 (See PNOR)||See Appendix D|
Annotated Z-3 Table Footnotes, Abbreviations, References Footnotes
(a) The unshaded area on this page Lists PELs from OSHA Table Z-3 in 29 CFR 1910.1000. The shaded area of this page lists other occupational exposure limits (OELs) from Cal/OSHA, NIOSH, and ACGIH®.
(b) Occupational Safety and Health Administration (OSHA) Permissible Exposure Limits (PELS) from 29 CFR 1910.1000. Z-3 Table [58 FR 35340, June 30, 1993; 58 FR 40191, July 27, 1993, as amended at 61 FR 56831, Nov. 4, 1996; 62 FR 1600, Jan 10,1997; 62 FR 42018, Aug. 4,1997; 71 FR 10373, Feb. 28, 2006; 71 FR 16673, Apr. 3, 2006; 71 FR 36008, June 23, 2006.]. PELs are 8-hour time weighted averages (TWAs) unless otherwise indicated. OSHA enforces these limits under section 5(a)(2) of the OSH Act.
(c) California Division of Occupational Safety and Health (Cal/OSHA) Permissible Exposure Limits (PELs) from Table AC-1 last updated March 17, 2012, viewable at http://www.dir.ca.gov/title8/5155table_ac1.html. Cal/OSHA enforces its PELs in workplaces under its jurisdiction. Cal/OSHA has established occupational exposure limits for compounds not included in the OSHA Z Tables. Please see Cal/OSHA Table AC-1 for additional limits, the most current limits, and other designations such as skin absorption. The Cal/OSHA AC-1 table and regulations should be consulted for explanations.
(d) National Institute for Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL) from NIOSH Pocket Guide to Chemical Hazards (http://www.cdc.gov/niosh/npg) (NIOSH 2007). RELs are for up to 10-hour time weighted averages (TWAs) during a 40-hour work week unless otherwise indicated. NIOSH has established occupational exposure limits for compounds not included in the OSHA Z Tables. Please see the NIOSH Pocket Guide for additional limits, skin absorption and other designations, and explanations.
(e) ACGIH® Threshold Limit Values (TLVs®) (ACGIH® 2015). TLVs® are listed in the order of 8-hour time weighted averages (TWAs), STELs (ST), and Ceilings (C), if available. ACGIH® has established TLVs® for compounds not included in the OSHA Z Tables. Please see ACGIH® Documentation for additional limits, skin absorption and other designations, and explanations. The 2015 TLV® and BEI® Book and Documentation of the Threshold Limit Values on Chemical Substances, 7th Edition are available through the ACGIH® website at http://www.acgih.org. The TLVs® and BEIs® are copyrighted by ACGIH® and are not publicly available. Permission must be requested from ACGIH® to reproduce the TLVs® and BEIs®. Click here for permission request form.
(f) Millions of particles per cubic foot of air, based on impinger samples counted by light-field techniques.
(g) Conversion factors - mppcf X 35.3 = million particles per cubic meter = particles per c.c.
(h) The percentage of crystalline silica in the formula is the amount determined from airborne samples, except in those instances in which other methods have been shown to be applicable.
(i) Containing less than 1% quartz; if 1% quartz or more, use quartz limit.
(j) All inert or nuisance dusts, whether mineral, inorganic, or organic, not listed specifically by substance name are covered by this limit, which is the same as the Particulates Not Otherwise Regulated (PNOR) limit in Table Z-1.
(k) Both concentration and percent quartz for the application of this limit are to be determined from the fraction passing a size-selector with the following characteristics:
|Aerodynamic diameter (unit density sphere)||Percent passing selector|
The measurements under this note refer to the use of an AEC (now NRC) instrument. The respirable fraction of coal dust is determined with an MRE; the figure corresponding to that of 2.4 mg/m3 in the table for coal dust is 4.5 mg/m3.
- Ca = Potential occupational carcinogens
- f/cm3 = fibers/cubic centimeter
- mg/m3 = milligrams/meter cubed
- PNOR = particulates not otherwise regulated
- resp. = respirable
- TLV® = Threshold Limit Value
- TWA = Time weighted average
ACGIH® 2015 Threshold Limit Values for Chemical Substances in the Work Environment. Adopted by ACGIH® with Intended Changes. See http://www.acgih.org/.
California Division of Occupational Safety and Health (Cal/OSHA) Table AC-1, Permissible Exposure Limits (PELs), in California Code of Regulations (CCR) Title 8 Section 5155, last updated March 17, 2012. Viewable at http://www.dir.ca.gov/title8/5155table_ac1.html.
National Institute for Occupational Safety and Health (NIOSH) (2007) NIOSH Pocket Guide to Chemical Hazards. Department of Health and Human Services. Centers for Disease Control and Prevention. National Institute for Occupational Safety and Health (NIOSH). September 2007. DHHS (NIOSH) Publication No. 2005-149. Available at http://www.cdc.gov/niosh/docs/2005-149/pdfs/2005-149.pdf.
Occupational Safety and Health Administration (OSHA) (2006) Air Contaminants. 29 CFR 1910.1000 [71 FR 16673, April 3, 2006]. Web site accessed on January 30, 2012. Available at http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=9991.
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