29 CFR 1910.1047: OSHA Ethylene Oxide Standard

Regulatory citation: 29 CFR 1910.1047, Ethylene Oxide

What Is the OSHA Ethylene Oxide Standard?

Section 1910.1047 covers all occupational exposure to ethylene oxide (EtO). EtO is a flammable gas used to sterilize medical devices and spices, and as a building block in chemical manufacturing. The standard affects contract sterilizers, hospital central supply departments, device manufacturers and chemical plants.

Processing, use or handling of products containing EtO is exempt where objective data show the product cannot release EtO at or above the action level, and an excursion above the excursion limit is not reasonably foreseeable, even under the conditions that cause the greatest release. The employer must keep those data for as long as it relies on them.

Why Ethylene Oxide Matters

EtO is a carcinogen and a reproductive hazard, and it is also highly flammable. Exposures often happen in short bursts, such as when a sterilizer door is opened or a load is moved to aeration, so short-term limits matter as much as the 8-hour average.

Core Obligations

1. Keep Exposure Below the Limits (1910.1047(b) and (c))

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

2. Monitor Exposure (1910.1047(d))

Where results are at or above the action level but at or below the TWA, monitoring is repeated at least every 6 months. Where results are above the TWA, it is repeated at least every 3 months, and can drop to every 6 months after two consecutive results, at least 7 days apart, are at or below the TWA. Results above the excursion limit also require monitoring at least every 3 months. TWA monitoring can stop when the initial result, or two consecutive results at least 7 days apart, are below the action level. Monitoring must restart after changes in production, process, controls, personnel or work practices.

3. Tell Employees Their Results (1910.1047(d)(7))

Employees must be notified within 15 working days, individually in writing or by posting. Where a limit was exceeded, the notice must describe the corrective action being taken.

4. Set Up Regulated Areas (1910.1047(e))

Areas where exposure may exceed the TWA or the excursion limit must be regulated, with access limited to authorized persons.

5. Use Controls and a Written Compliance Program (1910.1047(f))

Engineering and work practice controls come first. Where a limit is exceeded, a written compliance program is required. It must include a leak detection survey schedule and an emergency plan, and it must be reviewed at least every 12 months. Employee rotation may not be used to comply.

6. Provide Respirators When Needed (1910.1047(g))

Respirators are required while controls are being installed, during maintenance, repair and vessel cleaning where controls are not feasible, where controls are not enough, and in emergencies. Half-mask respirators are prohibited under the current text.

7. Plan for Emergencies (1910.1047(h))

Wherever an emergency release is possible, a written emergency plan meeting 1910.38 and 1910.39 is required. The employer must have a way to alert affected employees promptly, and they must evacuate immediately.

8. Provide Medical Surveillance (1910.1047(i))

Medical surveillance covers employees exposed at or above the action level for at least 30 days a year, regardless of respirator use, and anyone exposed in an emergency. Exams are due before assignment, at least annually, at termination or reassignment, after an emergency exposure, and on request about reproductive concerns. Each exam includes a complete blood count.

9. Train, Post Signs and Keep Records (1910.1047(j) and (k))

Training is required at initial assignment and at least annually for employees at or above the action level or above the excursion limit. Regulated area signs must warn that EtO may cause cancer and may damage fertility or the unborn child, and container labels follow the Hazard Communication Standard. Exposure records must be kept for at least 30 years, and medical records for the duration of employment plus 30 years.

Common Compliance Approaches

Sample the Short Tasks

Take 15-minute samples during door opening, load transfer, cylinder changes and aerator unloading. These tasks drive excursion limit compliance.

Run a Leak Detection Program

Use fixed or portable detectors on sterilizers, aerators and gas lines, and log each survey and repair.

Example: EtO Controls in Practice

A contract sterilizer samples its operators and finds 8-hour averages of 0.4 ppm, but 15-minute samples at the sterilizer door reach 7 ppm. It adds a purge cycle before the door opens, installs local exhaust over the door and moves loads to aeration with a powered cart. It also posts a regulated area, writes a compliance program with a leak survey schedule and an emergency plan, and resamples within 3 months. Operators exposed at or above the action level on 30 or more days a year get annual exams with a blood count.

Related regulations: OSHA respiratory protection, OSHA emergency action plans, OSHA access to exposure and medical records.

Note: In July 2025 OSHA proposed changes to the respirator provisions of this standard, including replacing the list of situations that require respirators with a cross-reference to 29 CFR 1910.134 and removing the half-mask ban. OSHA reopened the record in July 2026 and held a hearing in August 2026. No final rule had been issued as of October 2026, so check for updates. EPA also regulates EtO emissions from commercial sterilizers separately. State plan states may set stricter rules.

Frequently Asked Questions

What are the OSHA exposure limits for ethylene oxide?

The PEL is 1 ppm as an 8-hour TWA and the excursion limit is 5 ppm over 15 minutes. The action level is 0.5 ppm as an 8-hour TWA.

Who needs medical surveillance for EtO?

Employees exposed at or above the action level for at least 30 days a year, regardless of respirator use, and anyone exposed in an emergency.

Can a hospital be exempt from the EtO standard?

Only for processing or handling products where objective data show EtO cannot be released at or above the action level or above the excursion limit. A hospital that runs its own EtO sterilizer is covered.