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Incipient fires and breathing apparatus

Summary An employer asked how OSHA distinguishes incipient-stage from interior structural fires. OSHA said an incipient fire is small enough for initial firefighting without protective clothing or breathing apparatus. If smoke requires employees to wear breathing apparatus, OSHA said the fire is beyond that stage.
Document
Federal opinion letter
Agency
Occupational Safety and Health Administration (OSHA)
Document number
1981-12-02
Date issued
December 2, 1981
Status
Active
Status last verified October 10, 2026

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About this page: The full text below is the official document from Occupational Safety and Health Administration (OSHA). Ezel adds the plain-English summary and tracks the document's status. The official source linked on this page is authoritative for any reliance.

December 02, 1981

Mr. Allan Staib
Engineering Services
General Foods Corporation
Maxwell House Division
[Recipient address omitted]
Dear Mr. Staib:

This is in response to your letter of October 19, 1981, requesting a clarification of the Subpart L standards.

29 CFR 1910.155(c)(26) defines "incipient stage fire" as a fire which is in the initial or beginning stage and which can controlled or extinguished by portable fire extinguishers, class II standpipe or small hose systems without the need for protective clothing or breathing apparatus.

29 CFR 1910.155(c)(28) defines "interior structural fire fighting" as the physical activity of fire suppression, rescue or both, inside of buildings or enclosed structures which are involved in a fire situation beyond the incipient stage.

If your employees must wear breathing apparatus as you state in your letter because the smoke generated by a smolding fire is of such large quantity, then that fire can not be considered "incipient". "Incipient" infers a fire that has just begun and is of such size that poor visibility, smoke inhalation, and high temperatures have not reached the degree to require the use of breathing apparatus. We believe interior structural fires are fires of the type where it is necessary to wear breathing apparatus in order to be adequately protected.

I hope that the above information has clarified any questions you may have had with the standard.

If I may be of further assistance, please call or write.

Sincerely,
Patrick R. Tyson
Acting Director,
Federal Compliance and State Programs

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