Purpose and scope. This section covers areas in which the employer is aware that a
hazardous atmosphere or substance may exist, except where one or more of the following
sections apply: § 1917.22 Hazardous cargo; § 1917.24 Carbon monoxide; § 1917.25
Fumigants, pesticides, insecticides and hazardous preservatives; § 1917.73 Terminal
facilities handling menhaden and similar species of fish; § 1917.152 Welding, cutting, and
heating (hot work); and § 1917.153 Spray painting.
Determination of hazard.
When the employer is aware that a room, building, vehicle, railcar or other space contains or has
contained a hazardous atmosphere, a designated and appropriately equipped person shall test the atmosphere before employee entry to determine whether
a hazardous atmosphere exists.
Records of results of any tests required by this section shall be maintained for at least thirty
Testing during ventilation. When mechanical ventilation is used to maintain a safe atmosphere, tests
shall be made by a designated person to ensure that the atmosphere is not hazardous.
Entry into hazardous atmospheres. Only designated persons shall enter hazardous atmospheres, in which case the following shall apply:
Persons entering a space containing a hazardous atmosphere shall be protected by respiratory and
emergency protective equipment meeting the requirement of Subpart E of this part;
Persons entering a space containing a hazardous atmosphere shall be instructed in the nature of the
hazard, precautions to be taken, and the use of protective and emergency equipment. Standby observers, similarly equipped and instructed, shall
continuously monitor the activity of employees within such space;
Except for emergency or rescue operations, employees shall not enter into any atmosphere which has
been identified as flammable or oxygen deficient (less than 19.5% oxygen). Persons who may be required to enter flammable or oxygen deficient
atmospheres in emergency operations shall be instructed in the dangers attendant to those atmospheres and instructed in the use of self-contained
breathing apparatus, which shall be utilized.
To prevent inadvertent employee entry into spaces that have been identified as having hazardous,
flammable or oxygen deficient atmospheres, appropriate warning signs or equivalent means shall be posted at all means of access to those
When the packaging of asbestos cargo leaks, spillage shall be cleaned up by designated employees
protected from the harmful effects of asbestos as required by 1910.1001 of this chapter.
[48 FR 30909, July 5, 1983, as amended at 49 28551, July 13, 1984; 61 FR 5507, Feb. 13, 1996; 62 FR 40141, July 25, 1997; 65 FR 40938, June 30, 2000]