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Exposure Limit Lookup

Enter a substance name or CAS number.

Values render in the units their source records. To compare a ppm value against a mg/m³ value, use the ppm ↔ mg/m³ Converter.

Reference only. Not legal or regulatory advice. Verify against the primary source before you act.

How it works

Three limit systems are shown side by side: federal OSHA permissible exposure limits (PELs) from 29 CFR 1910.1000 Tables Z-1, Z-2 and Z-3; NIOSH recommended exposure limits (RELs) from the NIOSH Pocket Guide to Chemical Hazards; and EU occupational exposure limit values from the EU OEL directives, both indicative (IOELV) and binding.

OSHA PELs shown here are read from the 29 CFR 1910.1000 Z-tables, not from the NIOSH Pocket Guide's own transcription of them, so a single legal limit is never shown as two disagreeing numbers.

The OSHA Exposure Limit Lookup covers federal OSHA PELs alone and is unchanged. This tool is a superset by jurisdiction: it shows that same PEL alongside the NIOSH and EU limits for the same substance.

Units render exactly as each source records them. This tool performs no conversion between limit systems, so a PEL given in ppm and an REL given in mg/m³ are shown in their own units and are not made comparable here.

An entry reading “No limit in this dataset” means this source lists no limit for that substance. It does not mean the substance is unregulated, and it does not mean the substance is safe.

Reading the values

A ceiling value is a concentration the source records as not to be exceeded at any time, as distinct from a time-weighted average over a full shift.

A skin notation means the source flags absorption through the skin as a route that can contribute to overall exposure. It is not a limit value and does not change the airborne number.

EU values are marked binding or indicative as the source records them. The binding limit values shown here are set under Directive 2004/37/EC; an indicative value (IOELV) is set under the OEL directives and is transposed by member states, which may set stricter national limits.

Many of these limits are old. Federal OSHA PELs largely date to the original 1971 adoptions, and NIOSH records that many RELs predate its 1988 update. Where the source records a year of standard, it is shown next to the value.

For carbon black, the NIOSH carcinogen designation applies in the presence of polycyclic aromatic hydrocarbons (PAHs), not unconditionally; in that case NIOSH records an REL of 0.1 mg/m³ as PAHs. The condition is shown with the flag.

What is not covered

ACGIH Threshold Limit Values (TLVs) are not included. TLVs are proprietary, licensed content, so they are not ingested by this site from any source. A substance with no limit shown here may still carry a TLV.

Canadian occupational exposure limits are not covered. They are set provincially and territorially rather than federally, and no Canadian OEL dataset is committed to this repository — so this tool reports nothing for Canada rather than reporting an absence as a zero.

IDLH values (immediately dangerous to life or health) are not shown. An IDLH is an escape-condition threshold, not an occupational exposure limit, and the NIOSH dataset records it as “not determined” for many substances — a value this tool will not render as a number or treat as an absence of danger.

Sources

This tool is a reference: it reports occupational exposure limits exactly as the published sources record them. It does not advise, certify, or replace the primary source, and it does not assess anyone's exposure.

This is a screening aid for finding published limits. It is not a substitute for an exposure assessment by a qualified industrial hygienist.

Worked example

Searching 7782-50-5 (chlorine) returns all three systems at once: OSHA lists a ceiling of (C)1 ppm in Table Z-1, NIOSH records a ceiling REL of 0.5 ppm, and the EU carries a short-term value of 0.5 ppm / 1.5 mg/m³ with no long-term value at all. Three sources, three different numbers, each shown as its own source records it.

Searching 1333-86-4 (carbon black) shows the other case: OSHA and NIOSH both list a limit, and the EU column reads No limit in this dataset — an explicit statement that this source lists nothing, not an implication that the substance is unregulated or safe.

Searching 71-43-2 (benzene) shows a pointer rather than a number on the OSHA side: Table Z-1 defers benzene to its own standard, 1910.1028. The tool shows that pointer instead of inventing a value for it.

Sources

  • 29 CFR 1910.1000, Tables Z-1 / Z-2 / Z-3

    U.S. Occupational Safety and Health Administration

    open the source

  • NIOSH Pocket Guide to Chemical Hazards (DHHS (NIOSH) Publication No. 2005-149)

    U.S. National Institute for Occupational Safety and Health

    open the source

  • EU indicative OELV directives (2000/39/EC, 2006/15/EC, 2009/161/EU, 2017/164/EU, 2019/1831) and binding limit values under Directive 2004/37/EC

    European Union

    open the source

Related tools

Data vintage

  • Data: OSHA permissible exposure limits (Tables Z-1, Z-2, Z-3), U.S. Occupational Safety and Health Administration CFR 2024 annual edition (CFR-2024-title29-vol6, govinfo); section last amended 82 FR 2735, Jan 9 2017, retrieved 2026-07-13, 584 rows across the three tables.CAS numbers in Table Z-1 are informational only; enforcement is by substance name. A row reading "see 1910.xxxx" is governed by its own substance standard, so the tool shows that pointer rather than a number.
  • Data: NIOSH recommended exposure limits (Pocket Guide dataset), U.S. National Institute for Occupational Safety and Health 2023 supplementary dataset (figshare 24431042); September 2007 printing of the Pocket Guide as the verification backstop, retrieved 2026-07-29, 681 substances.OSHA PELs largely date to 1971 adoptions, and NIOSH records that many RELs predate the 1988 update. An IDLH recorded as "N.D." means no danger line was determined; it is not zero. Carbon black's carcinogen flag applies only in the presence of PAHs.
  • Data: EU occupational exposure limit values, European Union five indicative-OELV list exports and the CMRD Annex III export, retrieved 2026-07-18, 237 substances.82 rows carry a legally binding limit under Directive 2004/37/EC; the remainder are non-binding indicative values. 20 rows are name-keyed group entries carrying no CAS.

last updated 2026-08-15