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OSHA term · Glossary

Hexavalent Chromium

Verified vs OSHA sources · 2026-10-05

A toxic form of the metal chromium (chromium in the +6 oxidation state, "Cr(VI)") that is a confirmed carcinogen and a potent respiratory and skin irritant. It is produced during welding on stainless steel, chrome electroplating, and the use of chromate pigments and coatings. OSHA regulates Cr(VI) under 29 CFR 1926.1126 (construction) and 1910.1026 (general industry) with a permissible exposure limit of 5 µg/m³ as an 8-hour TWA and an action level of 2.5 µg/m³.

29 CFR 1926.112629 CFR 1910.102629 CFR 1926.1126(c)

Also known as: Cr(VI), chromium VI, chromium-6, hexavalent chrome

Hexavalent Chromium at a glance

  • PEL: 5 µg/m³ as an 8-hour TWA (29 CFR 1926.1126(c) / 1910.1026(c)).
  • Action level: 2.5 µg/m³ (8-hour TWA) — triggers monitoring and medical surveillance.
  • Confirmed carcinogen — causes lung cancer; also causes nasal septum ulceration/perforation and skin ulcers ('chrome holes').
  • A respiratory and skin sensitizer — can cause occupational asthma and allergic contact dermatitis.
  • Largest exposure source is welding, especially on stainless steel and chromium-containing alloys.
  • Other sources: chrome electroplating, chromate pigments/paints, and thermal cutting of coated metals.
  • The very low PEL (5 µg/m³) reflects the metal's high carcinogenic potency.

In plain English

A dangerous form of chromium created mainly by welding stainless steel and by chrome plating. Breathing it causes lung cancer and damages the nose and airways; touching it burns and sensitizes the skin. OSHA limits it to just 5 micrograms per cubic meter of air over a shift — a very low limit reflecting how hazardous it is.

What the rule says

“The employer shall ensure that no employee is exposed to an airborne concentration of chromium (VI) in excess of 5 micrograms per cubic meter of air (5 µg/m3), calculated as an 8-hour time-weighted average (TWA).”
29 CFR 1926.1126(c) — Permissible exposure limit (PEL)

In context

An enforcement, recordkeeping, or general-duty concept under the Occupational Safety and Health Act and 29 CFR. These terms define how OSHA inspects, cites, and penalizes employers.

29 CFR Chapter XVII

Where this is written in OSHA's rules

Example

A welder joining stainless-steel pipe in an enclosed area is monitored and found exposed to 4 µg/m³ Cr(VI) as an 8-hour TWA — above the 2.5 µg/m³ action level but below the 5 µg/m³ PEL. The employer must conduct periodic monitoring, provide medical surveillance, and implement engineering controls such as local exhaust ventilation to pull fume away from the welder's breathing zone. Moving the work to an area with better ventilation or adding a fume extractor can drop exposure well below the action level, reducing both cancer risk and monitoring burden.

Why it matters

Hexavalent chromium is a powerful carcinogen with one of the lowest metal PELs OSHA enforces, and welding on stainless steel — an extremely common industrial and construction task — is the leading source. Because the disease risk is lung cancer and the airway/skin damage can be permanent, controlling Cr(VI) fume through ventilation and, where necessary, respiratory protection is essential. The low 5 µg/m³ PEL means even routine welding can require monitoring and controls.

Hexavalent chromium (Cr VI) vs. trivalent chromium (Cr III)

Not all chromium is equally dangerous. Trivalent chromium (Cr III) is an essential trace nutrient and is far less toxic. Hexavalent chromium (Cr VI) is the carcinogenic, highly toxic form regulated by OSHA's Cr(VI) standard. The two are chemically distinct oxidation states, and many industrial processes — especially welding on stainless steel and chrome plating — convert or generate the hazardous Cr(VI) form. When people say 'chromium exposure' in a safety context, they almost always mean hexavalent chromium; the OSHA standard applies specifically to Cr(VI), not to chromium metal or Cr III.

Hexavalent Chromium — Limits & Health Effects

ItemDetail
PEL (8-hr TWA)5 µg/m³
Action level (8-hr TWA)2.5 µg/m³
CarcinogenLung cancer (confirmed)
RespiratoryNasal septum ulceration/perforation; occupational asthma (sensitizer)
SkinUlcers ('chrome holes'); allergic contact dermatitis
Top sourceWelding on stainless steel / chromium alloys

Hexavalent Chromium: frequently asked questions

What is the OSHA PEL for hexavalent chromium?
OSHA sets the hexavalent chromium PEL at 5 µg/m³ as an 8-hour time-weighted average, with an action level of 2.5 µg/m³. The same limits apply under the construction standard (29 CFR 1926.1126) and the general industry standard (1910.1026). Exceeding the action level triggers periodic exposure monitoring and medical surveillance.
Where are workers most exposed to hexavalent chromium?
The leading source is welding, especially on stainless steel and other chromium-containing alloys, where the welding fume contains Cr(VI). Other significant sources include chrome electroplating, the manufacture and application of chromate pigments and coatings, and thermal cutting of chromium-coated or -alloyed metals. Because welding is so widespread, hexavalent chromium exposure is a concern across both construction and general industry.
Is hexavalent chromium the same as regular chromium?
No. Chromium exists in different oxidation states. Trivalent chromium (Cr III) is a much less toxic form and is even an essential dietary trace element. Hexavalent chromium (Cr VI) is the carcinogenic, highly toxic form that OSHA's standard regulates. Industrial processes such as stainless-steel welding and chrome plating generate the hazardous Cr(VI) form, which is why the standard targets it specifically.

Related terms

More OSHA terms

Abatement

The action an employer takes to fix a cited violation or eliminate a hazard OSHA identified during an inspection. The citation sets an abatement date, the deadline to correct the hazard, and within 10 calendar days after that date the employer must certify to OSHA that the violation was abated. Failure to abate accrues additional penalties of up to $16,550 per day.

Area Director

The senior OSHA official in charge of a specific OSHA Area Office — the local unit that runs inspections and enforcement in its geographic territory. The Area Director has the authority to issue citations, propose penalties, hold informal conferences with employers, and approve settlement agreements. When a Compliance Safety and Health Officer (CSHO) completes an inspection, it's the Area Director who ultimately issues the citation.

Bureau of Labor Statistics (BLS)

The federal statistical agency within the U.S. Department of Labor that collects, analyzes, and publishes data on workplace injuries, illnesses, and fatalities. BLS conducts the annual Survey of Occupational Injuries and Illnesses (SOII) — compiled from employer OSHA 300 logs — and the Census of Fatal Occupational Injuries (CFOI). SOII data drives OSHA's Site-Specific Targeting (SST) program: establishments whose DART rates significantly exceed their BLS industry average are placed on the SST inspection list.

Competent Person

Under OSHA's construction standards, a person who is capable of identifying existing and predictable hazards in the surroundings or working conditions, and who has the authorization to take prompt corrective measures to eliminate them. The role requires both knowledge and the authority to act, and is mandated by name in many specific standards — excavations, scaffolds, fall protection, asbestos, and more.

Citation

The formal written notice OSHA issues to an employer after an inspection, describing each alleged violation, the standard cited, the proposed penalty, and the date by which the hazard must be corrected (abated). OSHA must issue a citation with reasonable promptness and no later than six months after the violation occurred.

Closing Conference

The meeting at the end of an OSHA inspection where the compliance officer confers with the employer and informally advises them of any apparent violations found. Importantly, the closing conference discusses what was observed and the employer's rights — but it does NOT state final citations or penalties, which come later in the written Citation and Notification of Penalty.

Compliance Officer (CSHO)

An OSHA Compliance Safety and Health Officer — the inspector who conducts workplace inspections. A CSHO presents credentials (a photo ID and a serial number), holds the opening conference, performs the walkaround, collects evidence, interviews employees, and recommends citations. CSHOs are either safety specialists or industrial hygienists.

Contest

An employer's formal challenge to an OSHA citation, penalty, or abatement date. To contest, the employer must file a written Notice of Contest with the OSHA Area Director within 15 working days of receiving the Citation and Notification of Penalty. Filing sends the case to the independent Occupational Safety and Health Review Commission (OSHRC); missing the deadline makes the citation a final, un-appealable order.

Sources & verification

Reviewed by HazComFast against eCFR, OSHA.gov, NIOSH, and the Federal Register. Last reviewed 2026-10-05. This glossary is general information, not legal advice; OSHA State-Plan states (e.g. California, Michigan) may adopt stricter requirements.

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