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Confined Space Definitions (1926.1202)


A confined space:

  • Is large enough and configured so a body can enter it
  • Has limited or restricted means of entry/exit
  • Is not designed for continuous employee occupancy


A permit-required confined space (PRCS) has one or more of the following:

  • Contains or has the potential to contain a hazardous atmosphere
  • Contains a material that has the potential for engulfment
  • Has an internal configuration such that an entrant could be trapped or asphyxiated by inwardly converging walls or by a floor which slops downward or tapers to a smaller cross-section
  • Contains any other recognized safety or health hazards (including physical hazards that can cause death of serious injury, such as explosives; mechanical, electrical, hydraulic or pneumatic energy; radiation; temperature extremes; engulfment; noise; chemicals that can damage the skin or eyes)
  • A low-hanging pipe or angle iron strut can impair the ability to exit and is considered a physical hazard


Hazardous atmosphere: may expose employees to the risk of death, incapacitation, impairment of ability to self-rescue or acute illness from one or more of the following:

  • Flammable gas, vapor or mist in excess of 10% of its lower flammable limit
  • Airborne combustible dust at a concentration that meets or exceeds its lower flammable limit (or obscures vision at 5 feet or less)
  • Atmospheric oxygen concentration below 19.5% or above 23.5%
  • Concentrations of toxic substances above OSHA permissible exposure limits (PELs) that could cause death, impairment of ability to self-rescue, injury or acute illness
  • Any other atmospheric conditions that are immediately dangerous to life or health

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