29 CFR 1910.1051: OSHA 1,3-Butadiene Standard

Regulatory citation: 29 CFR 1910.1051, 1,3-Butadiene

What Is the OSHA 1,3-Butadiene Standard?

Section 1910.1051 covers occupational exposure to 1,3-butadiene (BD), a gas used to make synthetic rubber, plastics and resins. It affects petrochemical plants, synthetic rubber and polymer producers, and terminals that handle BD.

Three situations are exempt. These are operations where objective data show exposure at or above the action level, or above the STEL, is not reasonably foreseeable; liquid mixtures containing 0.1% BD or less by volume, unless objective data show otherwise; and storage, transport, distribution and sale in intact containers or sealed pipelines, except for labeling and emergency response.

Why Butadiene Matters

BD is a carcinogen linked to leukemia and other blood cancers. It is stored and moved as a liquefied gas, so leaks from pumps, seals and loading connections are a common source of exposure.

Core Obligations

1. Keep Exposure Below the Limits (1910.1051(b) and (c))

The permissible exposure limit (PEL) is 1 part per million (ppm) as an 8-hour time-weighted average (TWA). The short-term exposure limit (STEL) is 5 ppm over 15 minutes. The action level is 0.5 ppm as an 8-hour TWA.

2. Monitor Exposure (1910.1051(d))

Initial monitoring is due within 60 days of introducing BD. Results at or above the action level but at or below both limits are repeated every 12 months. Results above the TWA or STEL are repeated every 3 months, moving to every 6 months once two samples at least 7 days apart show improvement. Monitoring can stop when the initial result, or two consecutive results at least 7 days apart, are below the action level and at or below the STEL. Extra monitoring is required after process changes and after spills, leaks or breakdowns.

3. Notify Employees (1910.1051(d)(7))

Results go to employees within 15 working days. Where a limit was exceeded, the written corrective action and schedule are also due within 15 days.

4. Set Up Regulated Areas and a Compliance Program (1910.1051(e) and (f))

Regulated areas are required where exposure exceeds or may exceed a PEL. Where a PEL is exceeded, a written compliance program with a leak detection survey schedule is required and must be reviewed at least every 12 months. Employee rotation may not be used.

5. Run an Exposure Goal Program (1910.1051(g))

Where exposure is above the action level, the employer must run a program to bring it below the action level during normal operations. Elements include leak detection and repair, ventilation maintenance, sealed pumps, closed gauging and unloading devices, and keeping control room levels below the action level. Respirators are not required under this program.

6. Provide Respirators and Change Cartridges on Schedule (1910.1051(h))

Respirators are required while controls are being installed, during maintenance and repair where controls are not feasible, where controls are not enough, and in emergencies. Air-purifying cartridges must be changed at the start of each shift and on the Table 1 schedule: every 4 hours up to 5 ppm, every 3 hours up to 10 ppm, every 2 hours up to 25 ppm and every hour up to 50 ppm. If a worker smells BD, the cartridge must be replaced immediately.

7. Provide Medical Screening and Surveillance (1910.1051(k))

Coverage applies to employees exposed at or above the action level on 30 or more days a year, or at or above a PEL on 10 or more days a year. It continues after transfer for employees with long past exposure histories set out in the standard. A health questionnaire and complete blood count with differential and platelets are done every year. A physical exam is due before assignment, every 3 years and at other points the standard lists. After an emergency exposure, screening is due within 48 hours, followed by a blood count every month for 3 months.

8. Train and Keep Records (1910.1051(l) and (m))

Training is required at or before initial assignment and at least annually. Objective data must be kept for as long as they are relied on, exposure records for at least 30 years, and medical records for the duration of employment plus 30 years.

Common Compliance Approaches

Focus on Fugitive Emissions

Most BD exposure comes from leaking seals, valves and sample points. A strong leak detection and repair program supports both the exposure goal program and air permits.

Track Cartridge Change Times

Write the change time on each cartridge and set the interval from the measured concentration band in Table 1.

Example: Butadiene Controls in Practice

A synthetic rubber plant samples its unloading operators and finds an 8-hour average of 0.7 ppm, above the action level but below the PEL. It starts an exposure goal program, replaces open sampling with closed-loop samplers and upgrades the pump seals at the unloading rack. Follow-up samples come in at 0.3 ppm. Operators who were above the action level on 30 or more days stay in the medical program with an annual questionnaire and blood count.

Related regulations: OSHA benzene standard, OSHA respiratory protection, OSHA access to exposure and medical records.

Note: In July 2025 OSHA proposed changes to the respirator provisions of this standard, replacing the list of situations that require respirators with a cross-reference to 29 CFR 1910.134 and tying respirator selection to assigned protection factors. The cartridge change schedules would remain. OSHA reopened the record in July 2026. No final rule had been issued as of October 2026, so check for updates. State plan states may set stricter rules.

Frequently Asked Questions

What is the OSHA PEL for 1,3-butadiene?

1 ppm as an 8-hour TWA, with a STEL of 5 ppm over 15 minutes. The action level is 0.5 ppm.

What is an exposure goal program?

A program required where exposure is above the action level, designed to bring exposure below the action level through leak repair, sealed equipment and ventilation rather than respirators.

How often are blood tests done for butadiene workers?

A complete blood count is done every year for covered employees, and monthly for 3 months after an emergency exposure.