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Note: This table only includes occupational exposure limits (OELs) for substances listed in the OSHA Z-2 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 OSHA Z-2 Table(a)

*Go to list of all footnotes
Regulatory Limits Recommended Limits
OSHA PELs(b) Cal/OSHA PEL(c)
(as of 10/2/2019)		 NIOSH REL(d)
(as of 10/18/2019)		 ACGIH® 2020 TLV®(e)
Substance 8-hour Time Weighted Average (TWA) Acceptable Ceiling Concentration Acceptable maximum peak above the acceptable ceiling concentration for an 8-hr shift
Concentration Maximum Duration 8-hour TWA
(ST) STEL
(C) Ceiling		 Up to 10-hour TWA
(ST) STEL
(C) Ceiling		 8-hour TWA
(ST) STEL
(C) Ceiling
Benzene(f) (Z37.40-1969) 10 ppm 25 ppm 50 ppm 10 min See Annotated Table Z-1
Beryllium and beryllium compounds(i)
(Z37.29-1970)		 2 µg/m3 5 µg/m3 25 µg/m3 30 min 0.2 µg/m3
(ST) 2 µg/m3
(C) 25 µg/m3		 Ca
See Appendix A		 0.05 µg/m3 (IHL)
Cadmium fume(g) (Z37.5-1970) 0.1 mg/m3 0.3 mg/m3 See Annotated Table Z-1
Cadmium dust(g) (Z37.5-1970) 0.2 mg/m3 0.6 mg/m3 See Annotated Table Z-1
Carbon disulfide (Z37.3-1968) 20 ppm 30 ppm 100 ppm 30 min 1 ppm
(ST) 12 ppm
(C) 30 ppm		 1 ppm
(ST) 10 ppm		 1 ppm
Carbon tetrachloride (Z37.17-1967) 10 ppm 25 ppm 200 ppm 5 min in any 4 hr 2 ppm
(ST) 10 ppm
(C) 200 ppm		 Ca
(ST) 2 ppm
[60-min]
See Appendix A		 5 ppm
(ST) 10 ppm
Chromic acid and chromates(h) (Z37-7-1971) 1 mg/10m3 See Chromium (VI) compounds in Annotated Table Z-1
Ethylene dibromide (Z37.31-1970) 20 ppm 30 ppm 50 ppm 5 min (C) 0.13 ppm,
See Section 5219		 Ca
0.045 ppm
(C) 0.13 ppm
[15-min]
See Appendix A		 See TLV® Documentation on Ethylene dibromide
Ethylene dichloride (Z37.21-1969) 50 ppm 100 ppm 200 ppm 5 min in any 3 hr 1 ppm
(ST) 2 ppm
(C) 200 ppm		 Ca
1 ppm
(ST) 2 ppm
See Appendix A
See Appendix C
Chloroethanes		 10 ppm
Fluoride as dust (Z37.28-1969) 2.5 mg/m3 2.5 mg/m3 2.5 mg/m3 2.5 mg/m3 as F
Formaldehyde
See 1910.1048		 See Annotated Table Z-1
Hydrogen fluoride (Z37.28-1969) 3 ppm 0.4 ppm as F
(ST) 1 ppm as F		 3 ppm
(C) 6 ppm
[15-min]		 0.5 ppm as F
(C) 2 ppm as F
Hydrogen sulfide (Z37.2-1966) 20 ppm 50 ppm 10 min once only if no other measurable exposure occurs. 10 ppm
(ST) 15 ppm
(C) 50 ppm		 (C) 10 ppm
[10-min]		 1 ppm
(ST) 5 ppm
Mercury (Z37.8-1971) 0.1 mg/m3 0.025 mg/m3
(C) 0.1 mg/m3
for metallic and inorganic		 0.05 mg/m3
(C) 0.1 mg/m3		 0.025 mg/m3 (elemental and inorganic)
Methyl chloride (Z37.18-1969) 100 ppm 200 ppm 300 ppm 5 min in any 3 hr 50 ppm
(ST) 100 ppm
(C) 300 ppm		 Ca
See Appendix A		 50 ppm
(ST) 100 ppm
Methylene Chloride
See 1910.1052		 25 ppm
(ST) 125 ppm
See Section 5202		 Ca
See Appendix A		 50 ppm
Organo (alkyl) mercury (Z37.30-1969) 0.01 mg/m3 0.04 mg/m3 0.01 mg/m3
(ST) 0.03 mg/m3
(C) 0.04 mg/m3		 0.01 mg/m3
(ST) 0.03 mg/m3		 0.01 mg/m3
(ST) 0.03 mg/m3
Styrene (Z37.15-1969) 100 ppm 200 ppm 600 ppm 5 min in any 3 hr 50 ppm
(ST) 100 ppm
(C) 500 ppm		 50 ppm
(ST) 100 ppm		 10 ppm
(ST) 20 ppm
Tetrachloroethylene 100 ppm 200 ppm 300 ppm 5 min in any 3 hr 25 ppm
(ST) 100 ppm
(C) 300 ppm		 Ca
See Appendix A		 25 ppm
(ST) 100 ppm
Toluene (Z37.12-1967) 200 ppm 300 ppm 500 ppm 10 min 10 ppm
(ST) 150 ppm
(C) 500 ppm		 100 ppm
(ST) 150 ppm		 20 ppm
Trichloroethylene (Z37.19-1967) 100 ppm 200 ppm 300 ppm 5 min in any 2 hr 25 ppm
(ST) 100 ppm
(C) 300 ppm		 Ca
See Appendix A
See Appendix C		 10 ppm
(ST) 25 ppm

Annotated Z-2 Table Footnotes, Abbreviations, References

(a) The unshaded area on this page Lists PELs from OSHA Table Z-2 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-2 Table; [62 FR 42018, August 4, 1997] as amended [71 FR 36009, June 23, 2006]. OSHA entries for beryllium and beryllium compounds from 82 FR 2470, January 9, 2017]. PELs are 8-hour time weighted averages (TWAs) unless otherwise indicated. OSHA enforces these limits under section 5(a)(2) of the OSH Act. In addition to the values listed in this table, the Z tables in 29 CFR 1910.1000 list skin absorption designations.

(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) (NIOSH 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 (TLV®s) (ACGIH® 2020). TLV®s 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 2020 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) This standard applies to the industry segments exempt from the 1 ppm 8-hour TWA and 5 ppm STEL of the benzene standard at 1910.1028.

(g) This standard applies to any operations or sectors for which the Cadmium standard, 1910.1027, is stayed or otherwise not in effect.

(h) This standard applies to any operations or sectors for which the exposure limit in the Chromium (VI) standard, Sec. 1910.1026, is stayed or is otherwise not in effect.

(i) This standard applies to any operations or sectors for which the exposure limits in the beryllium standard, § 1910.1024, are stayed or is otherwise not in effect.

Abbreviations

  • C = Ceiling limit
  • Ca = Potential occupational carcinogens
  • CAS No. = Chemical Abstract Service Number
  • hr = hour
  • m3 = cubic meters
  • mg/m3= milligram per cubic meter
  • min = minutes
  • ppm = parts per million
  • IHL = Inhalable
  • ST = Short Term Exposure Limit
  • TWA = Time Weighted Average
  • µg/m3 = microgram per cubic meter

References

ACGIH® 2020 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 https://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.

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