Massive vinyl chloride release under an emergency rule

NOTICE: This is an OSHA Archive Document, and may no longer represent OSHA Policy. It is presented here as historical content, for research and review purposes only.

February 13, 1981

MEMORANDUM FOR: ROGER CLARK
Regional Administrator

THRU: JOHN B. MILES, JR.
Director, Office of Field Coordination

FROM: BRUCE HILLENBRAND
Acting Director, Federal Compliance and State Programs

SUBJECT: November 4, 1980, Memorandum Requesting an Interpretation of 29 CFR 1910.1017(b)(5) and the Definition of "Massive Release" of Vinyl Chloride

The term "massive release" applies to a concentration of 100 ppm or higher of vinyl chloride in the general work area, or the general workroom air. It refers to an unexpected or uncontrolled release of vinyl chloride; i.e., leakage due to equipment failure such as from a relief valve, pipe leak or process (unit) leak which is considered an emergency.

November 4, 1980

SUBJECT: Interpretation of 1910.1017(b)(5). Definition of "Emergency".

TO: JOHN B. MILES, JR.
Director, Office of Field Coordination

A more detailed explanation of the term "massive release" in the subject definition is required. CPL 2-2.4 indicates that an unexpected release of vinyl chloride is "massive" where the concentration of VC is greater than 100 ppm. Was this explanation intended to refer to concentrations of VC in the general workroom air or in the worker's breathing zone? Or did it include a location directly at the point of a leak where the VC level would undoubtedly exceed 100 ppm? If the latter was meant, it would then be incumbent on employers to report to OSHA practically any unexpected release of this substance from a piping system, vessel, etc.

We would appreciate your comments in this regard.

Roger A. Clark
Regional Administrator