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OSHA term · Glossary

Formaldehyde

Verified vs OSHA sources · 2026-10-05

A colorless, pungent gas (often used in water solution as formalin) that is a confirmed carcinogen and a strong respiratory and skin sensitizer. It is used in resins, adhesives, composite wood products, embalming, and many laboratory and industrial processes. OSHA regulates it under 29 CFR 1910.1048 with a permissible exposure limit of 0.75 ppm as an 8-hour TWA, a short-term exposure limit (STEL) of 2 ppm over any 15-minute period, and an action level of 0.5 ppm.

29 CFR 1910.104829 CFR 1910.1048(c)

Also known as: formalin, methanal, HCHO

Formaldehyde at a glance

  • PEL: 0.75 ppm as an 8-hour TWA (29 CFR 1910.1048(c)(1)).
  • STEL: 2 ppm averaged over any 15-minute period (1910.1048(c)(2)).
  • Action level: 0.5 ppm (8-hour TWA) — triggers monitoring and medical surveillance.
  • Confirmed carcinogen (nasopharyngeal cancer, leukemia) and a strong respiratory + skin sensitizer.
  • Two labeling thresholds: materials releasing formaldehyde at or above 0.1 ppm must identify it on the label (1910.1048(m)(1)(iv)); above 0.5 ppm the label must also carry 'May Cause Cancer' (m)(2)(i).
  • Medical surveillance required for exposure at/above the action level or exceeding the STEL.
  • Common sources: composite/pressed wood products, resins and adhesives, embalming, histology/pathology labs, and permanent-press textiles.

In plain English

A sharp-smelling chemical used in glues, pressed-wood products, and embalming fluid. It causes cancer and can trigger asthma and allergic skin reactions. OSHA caps it at 0.75 ppm over a shift and 2 ppm over any 15 minutes, and any material that can release formaldehyde above 0.5 ppm must carry a "May Cause Cancer" warning.

What the rule says

“The employer shall assure that no employee is exposed to an airborne concentration of formaldehyde which exceeds 0.75 parts formaldehyde per million parts of air (0.75 ppm) as an 8-hour TWA. … The employer shall assure that no employee is exposed to an airborne concentration of formaldehyde which exceeds two parts formaldehyde per million parts of air (2 ppm) as a 15-minute STEL.”
29 CFR 1910.1048(c) — Permissible exposure limits

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 hospital histology lab uses formalin to preserve tissue specimens. Air monitoring at a grossing station shows short-term exposures reaching 2.5 ppm during specimen handling — above the 2 ppm STEL. The employer must add local exhaust ventilation (a downdraft or ducted grossing station), reassess exposures, enroll affected technicians in medical surveillance, and ensure formalin containers carry the required cancer-hazard labeling. Reducing the 15-minute peak below 2 ppm and the 8-hour average below the 0.75 ppm PEL brings the station into compliance.

Why it matters

Formaldehyde is both an acute irritant — causing eye, nose, and throat irritation and triggering asthma in sensitized workers — and a long-term carcinogen. Its wide use in wood products, resins, healthcare, and labs means exposure is common. The dual PEL/STEL structure controls both the chronic cancer risk (8-hour average) and the acute sensitization and irritation risk (15-minute peaks), while the labeling requirement propagates the cancer warning through the supply chain.

Formaldehyde PEL vs. STEL — chronic vs. acute control

Formaldehyde's two air limits guard against two different hazards. The 0.75 ppm PEL is an 8-hour average that controls the long-term, cumulative cancer risk. The 2 ppm STEL caps short 15-minute peaks that drive acute effects — eye/nose/throat irritation and asthma attacks in sensitized workers. A task can comply with the 8-hour PEL yet still violate the STEL during a brief high-exposure step (like pouring formalin), so both must be evaluated. The separate 0.5 ppm action level, below the PEL, triggers monitoring and medical surveillance before either limit is exceeded.

Formaldehyde Exposure Limits (29 CFR 1910.1048)

LimitValueAveraging Period / Role
PEL0.75 ppm8-hour TWA (chronic/cancer control)
STEL2 ppmAny 15-minute period (acute/irritation control)
Action level0.5 ppm8-hour TWA (triggers monitoring + surveillance)

Formaldehyde: frequently asked questions

What is the OSHA permissible exposure limit for formaldehyde?
Under 29 CFR 1910.1048, the formaldehyde PEL is 0.75 ppm as an 8-hour time-weighted average, with a short-term exposure limit (STEL) of 2 ppm over any 15-minute period. The action level is 0.5 ppm as an 8-hour TWA, which triggers exposure monitoring and medical surveillance.
Does formaldehyde have to be labeled as a carcinogen?
Yes, and at two different levels. Materials capable of releasing formaldehyde at concentrations reaching or exceeding 0.1 ppm — along with mixtures over 0.1 percent formaldehyde — must be labeled to indicate that formaldehyde is present (1910.1048(m)(1)(iv)). Above 0.5 ppm, the label must additionally address all the hazards and carry the statement 'May Cause Cancer' (m)(2)(i), covering sensitization and irritation as well. A product releasing 0.3 ppm is therefore not exempt from labeling — it simply does not yet carry the cancer statement.
Why does formaldehyde have both a PEL and a STEL?
Because it causes both long-term and short-term harm. The 0.75 ppm 8-hour PEL controls the cumulative cancer risk from average daily exposure. The 2 ppm 15-minute STEL controls acute effects — eye, nose, and throat irritation and asthma attacks in sensitized workers — that come from brief high-concentration peaks. A task can satisfy the 8-hour average while still exceeding the STEL during a short high-exposure step, so employers must evaluate both limits.

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.

Put Formaldehyde into practice

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