Permissible Exposure Limits – Annotated Tables
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.
Annotated TABLE Z-3 Mineral Dusts(a)
| Regulatory Limits | Recommended Limits | ||||
|---|---|---|---|---|---|
| OSHA PEL(b) | Cal/OSHA PEL(c) 8-hour TWA (as of 11/12/2021) |
NIOSH REL(d) Up to 10-hour TWA (as of 11/16/2021) |
ACGIH® TLV®(e) 8-hour TWA |
||
| Substance | mppcf(f)(g) | mg/m3 | mg/m3 | mg/m3 | Complimentary access on acgih.org |
| Silica: Crystalline | SILICA, CRYSTALLINE — α-QUARTZ AND CRISTOBALITE - ACGIH | ||||
| Quartz (Respirable)(l) | 250(h) (%SiO2+5) |
10 mg/m3(k) (%SiO2+2) |
See Annotated Z-1 |
See Annotated Z-1 |
See Annotated Z-1 |
| Cristobalite(l) | Use ½ the value calculated from the count or mass formulae for quartz. |
See Annotated Z-1 |
See Annotated Z-1 |
See Annotated Z-1 |
|
| Tridymite(l) | Use ½ the value calculated from the formulae for quartz. |
See Annotated Z-1 |
See Annotated Z-1 |
See Annotated Z-1 |
|
| Amorphous, including natural diatomaceous earth | 20 | 80 mg/m3 (%SiO2) |
6 (total) 3 (resp.) |
6 | |
| Silicates (less than 1% crystalline silica): | |||||
| Mica | 20 | 3 (resp.) | 3 (resp.) | MICA - ACGIH | |
| Soapstone | 20 | 6 (total) 3 (resp.) |
6 (total) 3 (resp.) |
||
| Talc (not containing asbestos) | 20(i) | 2 (resp.) | 2 (resp.) | TALC - ACGIH | |
| Talc (containing asbestos) | Use asbestos limit | See Section 5208 | Use asbestos limit Ca 0.1 f/cm3 |
||
| Tremolite, asbestiform | See 29 CFR 1910.1001 | Ca 0.1 f/cm3 See Appendix A See Appendix C |
|||
| Portland cement | 50 | See PNOR | 10 (total) 5 (resp.) |
PORTLAND CEMENT - ACGIH | |
| Graphite (Natural) | 15 | 2.5 (resp.) | 2.5 (resp.) | GRAPHITE, ALL FORMS EXCEPT GRAPHITE FIBERS - ACGIH | |
| Coal Dust: | 1 See Appendix C |
COAL DUST - ACGIH | |||
| Respirable fraction less than 5% SiO2 | 2.4 mg/m3 (k) | 0.9 (bituminous) | COAL DUST - ACGIH | ||
| Respirable fraction greater than 5% SiO2 | 10 mg/m3 (k) (%SiO2+2) |
0.1 (bituminous) | COAL DUST - ACGIH | ||
| Inert or Nuisance Dust: (j) | |||||
| 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
(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]. [OSHA entries for respirable crystalline silica from 81 FR 16285, March 25, 2016] 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 viewed October 2, 2019, 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 Limits (RELs) from the NIOSH Pocket Guide to Chemical Hazards (http://www.cdc.gov/niosh/npg) (Web site accessed on October 18, 2019). 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®). 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 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 |
|---|---|
| 2 | 90 |
| 2.5 | 75 |
| 3.5 | 50 |
| 5 | 25 |
| 10 | 0 |
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.
(l) This standard applies to any operations or sectors for which the respirable crystalline silica standard, 1910.1053, is stayed or is otherwise not in effect.
Abbreviations
- 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
References
ACGIH® 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 viewed October 2, 2019. Viewable at http://www.dir.ca.gov/title8/5155table_ac1.html.
National Institute for Occupational Safety and Health (NIOSH) (2019) 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). Web site accessed on October 18, 2019. Available at http://www.cdc.gov/niosh/npg
Occupational Safety and Health Administration (OSHA) (2017) Air Contaminants. 29 CFR 1910.1000 [82 FR 2735, January 9, 2017]. Web site accessed on April 4, 2018. Available at http://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000.