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.

March 10, 1986

Mr. Donald G. Mader
Safety Coordinator
Formosa Plastics Corporation
Texas P.O. Box 400
Point Comfort, Texas 77978

Dear Mr. Mader:

Your letter of January 31, requesting an interpretation of section (b)(5) and (n)(2) of the Occupational Safety and Health Administration's (OSHA) vinyl chloride standard (29 CFR 1910.1017) has been referred to us for reply.

Your stated concern is over the definitions of the terms "emergency", "equipment failure", and "massive release" as used in 1910.1017. The use of those terms in sections (b)(5) and (n)(2) is not intended to apply to ordinary leaks or operations resulting in small, controllable amounts of vinyl chloride being released into the workplace environment. These are not emergencies. These terms, as used in the standard, refer to situations in which there is a potential for loss of control and a need for immediate action to contain a sudden, unexpected and relatively large release of vinyl chloride much beyond any quantity that would be involved in a small leak.

The term "massive release" cannot be quantified, since the circumstances surrounding the release of any toxic substance vary. Such factors as the amount released (relative to the space into which it is released), as well as the average amount which may be released under normal conditions, will determine the degree of "massiveness" of the release. The term "massive release", used in conjunction with the concept of an emergency situation refers to something more than a small leak of a highly toxic material. In this context it implies the existence of an uncontrolled and potentially uncontrollable situation requiring immediate action to prevent overexposure (i.e., exposures in excess of the permissible exposure limits).

Continuing with this line of reasoning, "equipment failure" would not refer to minor flange leaks, unless those leaks involved a sudden and/or continuous and uncontrolled release of large quantities of vinyl chloride to the extent that an immediate danger of human overexposure and the potential for evacuation of the area were involved. A break in a pipe or tank containing vinyl chloride might be considered such an equipment failure. The controlled purging of a pump with appropriate protective measures taken is not.

The purpose of the reporting requirement is to assure that steps are taken to prevent employee overexposure which might result from any sudden, and unexpected release of vinyl chloride in excess of those amounts normally anticipated and prepared for (i.e., by the use of engineering, work practice and/or administrative controls of the use of personal protective clothing and equipment).

The operation of a relief device in a situation in which the release of vinyl chloride is (or could be) such that there is the potential for human overexposure due to the uncontrolled and potentially uncontrollable nature of the release, is considered an emergency and is reportable under 29 CFR 1910.1017(n)(2).

Apart from the question of emergencies, whether your employees are repairing flange leaks, doing preventive maintenance on pumps, or doing any other job in your establishment, their exposures to vinyl chloride must not exceed the limits required by the standard.

I hope we have adequately addressed your question and concerns regarding 29 CFR 1910.1017. If we can be of any further assistance, we can be reached at the following address:

U.S. Department of Labor - OSHA
200 Constitution Avenue, N.W.
Room N-3691
Washington, D.C. 20210
Telephone: (202) 523-7031

Thank you for your interest in occupational safety and health.


Edward J. Baier
Directorate of Technical Support

January 31, 1986

U.S. Department of Labor
Corpus Christi Area Office
Government Plaza
400 Mann St., Room 300
Corpus Christi, Texas 78401

Attention: Mr. R.L. Mike Hunter, Area Director

Dear Mr. Hunter:

We are requesting an interpretation of CFR 1910.1017 (b) (5) and CFR 1910.1017 (n) (2). In particular please address the following questions in detail:

A. 1910.1017 (b) (5) "Emergency means any occurrence such as, but not limited to, equipment failure, or operation of a relief device which is likely to, or does result in a massive release of vinyl Chloride."

1. Please define "massive relief" in terms of parts per million and/or duration of exposure. (NOTE: we were given a verbal interpretation that this means exposure to one ppm or more over an eight hour period or five ppm or more in fifteen minutes.)

2. Please define "Equipment Failure". Does this mean, for example, a flange leak or maintenance on a pump?

We see this as a real problem if we have:

(a) A flange leak of six (6) ppm (as measured from a distance of three inches from the flange with a portable organic analyzer) might require that a maintenance man merely tighten the bolts to stop the leak while wearing an air-pac. In your mind, does this describe (1) An "Equipment failure" and (2) a "massive release?"

(b) To repair a pump on a preventative maintenance basis. The pumps in question are purged with both steam and nitrogen prior to being disassembled but always have residual VCM in water in the base of the pump that average 20 to 30 ppm. The pump has to be disassembled (and there by exposing maintenance personnel wearing air-pacs) before this last small amount of water can be cleaned out. In your mind, does this constitute an "Equipment Failure" and a "Massive Release?"

(c) An operation of relief valve ninety (90) feet in the air due to over pressurization of, for example, a reactor with no one in the area. The OSHA definition of emergency states "...or operation on a relief device which is likely to or does result in a massive release of Vinyl Chloride." The closest an employee could be to the relief device would be at the fifty-seven (57) foot level of the reactor building. Depending on wind direction and speed, if an employee were in the area at the 57 foot level he might be exposed to 6 ppm or more. If no employees were in the area of a relief valve actuation do we consider this as falling under the definition of an "Emergency".

B. CFR 1910.1017 (n) (2) "Emergencies, and the facts obtainable at that time shall be reported within 24 hours to the OSHA Area Director. Upon request of the Area Director, the employer shall submit additional information in writing relevant to the nature and extent of employee exposures and measures taken to prevent future emergencies of a similar nature."

(a) Are we to report to the Area Director incidents such as the examples of given previously of tightening a leaking flange or repairing a pump?

(b) How are we to prevent "Emergencies...and measures taken to prevent future emergencies of similar nature" when we have to do routine maintenance of pumps? Short of permanently shutting down the plant we see no solution. Is this OSHA's aim?

Please interpret your definitions and/or answer our questions in detail at your earliest convenience since our Administration, Production Dept. and Maintenance Dept. are an uproar over how CFR 1910.1017 (b) (5) and (n) (2) are to be handled.


Donald C. Mader
Safety Coordinator