OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at https://www.osha.gov.


January 13, 1987

Mr. George L. Notarianni
Gas Monitoring & Analysis, Inc.
P.O. Box 163
Novi, Michigan 48050

Dear Mr. Notarianni:

This is in response to your letter of November 26 requesting clarification of 29 CFR 1910.1047 - Occupational Exposure to Ethylene Oxide.

The Occupational Safety and Health Administration (OSHA) defines an emergency situation as "an occurrence such as but not limited to equipment failure, rupture of containers, or failure of control equipment that may result in an unexpected significant release of EtO". Quantities of EtO sufficient to produce acute toxic effects is exposed employees constitute such an emergency.

Section 29 CFR 1910.1047(h)(1) requires written plans for emergency situations to be developed for each workplace where there is a possibility of an emergency. These plans shall be written in accordance with 29 CFR 1910.38 (Employee Emergency Action Plans and [29 CFR 1910.39] Fire Prevention Plans).

Paragraph (h)(2) of the standard requires some method of alerting employees of an emergency promptly. OSHA gives the employer the flexibility to choose any effective method of alerting employees, including communication systems, voice communication system, or a bell or other alarm. If the employer choose to install an emergency alarm system, the system must meet the requirements of 29 CFR 1910.165 (Employee Alarm System). However, it should on mentioned that 29 CFR 1910.165(b)(5) states the following:

"For those employees with 10 or fewer employees in a particular workplace, direct voice communication is an acceptable procedure for sounding the alarm provided all employees can hear the alarm."

Therefore, a sophisticated alarm system might be unnecessary for some facilities such as small hospitals with only one EtO sterilizer.

In response to your specific questions:

Question 1: Does an institution need to install an alarm sensitive down to one ppm PEL?

Answer: At this time, the ethylene oxide standard does not require an institution to install an alarm system sensitive down to one ppm. However, the standard does require monitoring and some method of alerting employees of an emergency.

Question 2: With the proposed court mandated institution of an STEL for EtO, would it be appropriate for an EtO alarm to measure EtO exposure down to the STEL of 10 ppm as originally proposed by OSHA?

Answer: The current standard does not include a STEL therefore, at this time it would not be appropriate for an alarm system to measure down to 10 ppm. OSHA is still gathering data to support STEL. This part of the standard is expected to be finished by March 1987.

[This document was edited on 02/05/2004 to strike information that no longer reflects current OSHA policy. On April 6, 1988 an excursion limit of 5ppm was published in the Federal Register 53:11414-38 and codified at 1910.1047(c)(2).]

Question 3: If an employer has not complied yet with the provision, are they in violation of the ethylene standard?

Answer: Yes, if an employer has not instituted an effective method of alerting employees they are in violation of the standard.

Please feel free to contact us if further assistance is needed.


John B. Miles, Jr., Director
Directorate of Field Operations


November 26, 1986

Mr. John Miles
Director of Field Operations
Room N-3603
Occupational Safety & Health Administration
Department of Labor
200 Constitution Avenue, N.W.
Washington, D.C. 20210

Dear Mr. Miles:

Re: 29 CFR Part 1910 Occupational Exposure to Ethylene Oxide

I would like clarification of specific aspects of the above-mentioned OSHA standard. My questions concern the following passages an published in the Federal Register on Friday, June 22, 1984.

Page 25797 Section (h) Emergency situations (2) Alerting employees:

"Where there is the possibility of employee exposure to EtO due to an emergency, means shall be developed to alert potentially affected employees of such occurrences promptly. Affected employees shall be immediately evacuated from area in the event that an emergency occurs."

Page 25783 Section (h) Emergency situations:

"Paragraph (h) of OSHA's final rule for EtO requires that employers develop written plans for emergency situations ... and that they develop methods of alerting employees of these situations and evacuating workers when necessary ... Employers must also be prepared to alert employees to evacuate the workplace in the event of an emergency ... These requirements are identical to the emergency situation requirements included in the EtO proposal (48 FR 17284, April 21, 1983.) The purpose of this provision is to protect workers from unexpected significant releases of EtO that pose an acute or other health risk."

Page 25874 Section (h) Emergency situations:

"Since EtO's odor warning threshold is about 700 ppm, and since this level is substantially above levels identified as having adverse health impacts, OSHA has chosen not to use odor threshold to define an EtO-related emergences defined in the final rule ... the term emergency covers those unexpected occurrences, such as failure of control equipment, that might produce a release of EtO of sufficient size to produce significant acute effects, including eye or respiratory irritation."

It is my understanding that the above-quoted passages underscore OSHA's position that employers with EtO gas sterilizers; such as hospitals, must have something that measures EtO specifically in order to determine an EtO emergency situation. Since the final standard specifically eliminates odor threshold as a method of defining an EtO-related emergency, an institution must therefore install some type of EtO specific "alarm system" in order to be able to define an EtO emergency situation and alert potentially effected employees promptly. Therefore, in order to be in compliance with this Federal standard, an institution must install an EtO alarm system.

I would also like clarification as to what OSHA considers an acceptable EtO low level sensitivity of such an alarm system. Specifically, does an institution need to install an alarm sensitive down to one ppm PEL? With the proposed court mandated institution of an STEL for EtO, would it be appropriate for an EtO alarm to measure EtO exposure down to the STEL of 10 ppm as originally proposed by OSHA?

Finally, it is my understanding that the provision for the installation of an "EtO alarm system" became binding and mandatory as of September 9, 1985. Therefore, all employees utilizing EtO gas sterilizers should have installed an "EtO alarm system" by that deadline. If an employer has not complied yet with the provision, they would be in violation of the above-mentioned Federal standard.

I would appreciate a formal response to these questions as possible. Thank you for your timely attention to this matter.



George L. Notarianni