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 http://www.osha.gov.

November 15, 1999

Ms. Kelly Boyle
American Safety Training, Inc.
317 W. 4th Street
Davenport, Iowa 52801-1204

Dear Ms. Boyle:

Thank you for your October 28, 1999 letter to the Occupational Safety and Health Administration's (OSHA's) Office of General Industry Compliance Assistance (GICA) for an answer regarding OSHA's Permit-Required Confined Spaces standard, 29 CFR 1910.146. Based on your telephone conversation with Mr. Patrick Kapust of my staff, your specific questions have been further revised and restated below for clarity.

Question 1:

Would a testing chamber, that can go from an extremely cold to an extremely hot temperature, similar in design to a walk-in freezer be considered a confined space if the chamber does not have a limited or restricted means for entry or exit?

Response: No, a testing chamber which does not have a limited or restricted means for entry or exit would not be considered a confined space as defined in 29 CFR 1910.146. A Confined Space means a space that: (1) Is large enough and so configured that an employee can bodily enter and perform assigned work; and (2) Has limited or restricted means for entry or exit; and (3) Is not designed for continuous employee occupancy.

Question 2:

Would a testing chamber (with the same hazards mentioned above, including a potential oxygen deficient atmosphere) with a three foot portal as its means of entry and exit be considered a confined space and/or a permit-required confined space?

Response: A testing chamber which has a limited or restricted means for entry or exit (such as a three foot portal) would be considered a confined space as long as the other aspects of the definition as described above are met. Further, the testing chamber would be considered a Permit-required confined space since it has a potential to contain a hazardous atmosphere (oxygen deficiency) and other recognized serious safety or health hazard(s) (heat/cold stress).

Question 3:

Given the scenario in Question 2, could alternative procedures as defined in §1910.146(c)(5)(ii) be used for entering this testing chamber if every hour a new atmosphere would be introduced by forced air ventilation?

Response: An employer may only use the alternate procedures specified in 1910.146(c)(5)(ii) under the conditions set forth in 1910.146(c)(5)(i)(A) through (F). The scenario described in Question 2 has a potential hazardous atmosphere (oxygen deficiency) and other serious safety or health hazard(s) (heat/cold stress). The first condition set forth in using alternative procedures is that the employer must demonstrate that the only hazard posed by the permit space is an actual or potential hazardous atmosphere. Since this space would have other hazards such as heat/cold stress (which is not considered an atmospheric hazard but rather a physical hazard) aside from the atmospheric hazard (oxygen deficiency), the first condition would not be met and therefore, alternative procedures could not be used.

The second condition set forth states that the employer must demonstrate that continuous forced air ventilation alone is sufficient to maintain that permit space safe for entry. In addition, the employer must have monitoring and inspection data that supports this demonstration. Changing the atmosphere every hour may not be sufficient to maintain the permit space for entry. Merely having a new atmosphere every hour without the supporting monitoring and inspection data would not meet the conditions for using alternative procedures.

Thank you for your interest in occupational safety and health. We hope you find this information helpful. Please be aware that OSHA's enforcement guidance is subject to periodic review and clarification, amplification, or correction. Such guidance could also be affected by subsequent rulemaking. In the future, should you wish to verify that the guidance provided herein remains current, you may consult OSHA's website at http://www.osha.gov. If you have any further questions, please feel free to contact the Office of General Industry Compliance Assistance at (202) 693-1850.

Sincerely,

Richard E. Fairfax, Director
Directorate of Compliance Programs