Providing Full Protection

Match your entry procedures to the permit space's hazards.

PERMIT-required confined spaces are death traps if entry teams don't take proper precautions. OSHA allows some options on how to approach permit space entries. Employers can determine the proper entry procedures only after they have identified permit spaces and understand the hazards.

Surveying the Space
Federal OSHA's requirements start simply enough: Evaluate the workplace to determine whether or not permit spaces are present. Starting with a fresh slate, the employer conducts a facility assessment to find any space that meets OSHA's definition of a confined space. If there are confined spaces, the next step is to determine whether the spaces are permit-required. At this point, there are no further compliance obligations if every confined space contains no hazards that would make it a permit space.

However, this is not a one-time assessment. The installation of new equipment could introduce permit spaces. Material and procedural changes can turn a non-permit space into a permit space--even for a one-time job. Employers who did not have any permit spaces when OSHA's standard became effective in 1993 should continue to keep permit space requirements in mind: OSHA issued 1,168 citations for violations of 29 CFR 1910.146 during 2003.

Defining the Space
OSHA's definition of a "confined space" is a space that:

1. Is large enough for an employee to enter and work,
2. Has limited or restricted means of entry and exit, and
3. Is not designed for continuous occupancy.

A space must meet all three of these criteria in order to be classified as a confined space.

A space must first meet the definition of confined space before it can be a permit space. OSHA defines a "permit-required confined space" as a confined space that has one or more of the following characteristics:

  • Contains or has a potential to contain a hazardous atmosphere,
  • Contains a material that has the potential for engulfing an entrant,
  • Has an internal configuration that could trap or asphyxiate an entrant by inwardly converging walls or a floor that slopes downward and tapers to a small cross section, or
  • Contains any other recognized serious safety or health hazard.

An OSHA letter of interpretation (LOI) dated Nov. 15, 1999, helps illustrate the application of these definitions:

"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.

"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)."

In the above LOI, OSHA did not address the example of a testing chamber that has a potential for an oxygen-deficient atmosphere even though it does not have a limited or restricted means for entry or exit. Because the space still does not meet the definition of a confined space, it could not be a permit space. In this situation, the employer would need to consider the presence of air contaminants (1910.1000) and address the immediately dangerous to life or health atmospheric hazard through OSHA's standard on respiratory protection (1910.134).

Recognizing an Entry
Employees need to be made aware of permit spaces through posting danger signs "or by any other equally effective means" of the existence, location, and dangers of the space.

As a good practice, the entrance to the space can be securely locked to ensure no one can enter. This is an especially good idea if no employees will be allowed to enter permit spaces. If this is the case, permit spaces must still be identified, employees must be informed, the assessment must be re-evaluated as necessary, and certain precautions must be taken when contractors are hired to enter the permit spaces.

But just what is an entry? Would OSHA allow someone to just reach into an opening to use a tool without having to go through the permit process? The standard states (at 1910.146(b)) that entry is "considered to have occurred as soon as any part of the entrant's body breaks the plane of an opening into the space." In support of this, an OSHA LOI dated Oct. 20, 1999, states that "The term 'body' refers to any part of the anatomy including all extremities."

As an example, consider the consequences if an employee, without taking the precautions dictated by an entry permit, reaches into a tank opening to use a grinder on the inside tank wall. If the tank contains a flammable atmosphere, a spark could ignite a flash fire or explosion that could seriously injure or kill the employee at the opening even though only a part of his body has entered the space.

An OSHA LOI dated Oct. 18, 1995, further clarifies this issue and offers examples of how a partial entry would entail a "de minimis" violation (for which OSHA would issue no citation) only if it does not expose the entrant to the possibility of injury or illness. For example, an employee who reaches into a horizontal permit space would not be exposed to energized parts that were 10 feet from the opening.

Full Compliance
Entry into a permit space must be documented and authorized through the use of an entry permit. The entry permit must identify:

  • The permit space
  • The purpose for the entry
  • The date and duration of the permit
  • The authorized entrants
  • The attendants
  • The entry supervisor
  • The hazards
  • The measures to eliminate or control hazards
  • The acceptable entry conditions
  • The monitoring or test results
  • The rescue services
  • The communication procedures
  • The necessary equipment
  • Any other necessary information
  • Any additional permits.

The permit is only a part of the compliance effort. Full compliance requires meeting the standard's provisions for:

  • Permit space program
  • Permit system and entry permits
  • Training
  • Authorized entrants
  • Attendants
  • Entry supervisors
  • Rescue and emergency services.

In some situations, OSHA allows employers to streamline entry procedures when the hazards indicate a full permit space program is unnecessary.

If the permit space has no actual or potential atmospheric hazards and all the other hazards within the space are eliminated without entering the space following lockout/tagout procedures outlined in 1910.146(c)(7), then the space can be reclassified as a non-permit space for as long as the non-atmospheric hazards remain eliminated.

OSHA discusses reclassification of a permit space in the following excerpt from the preamble to the final rule, published in the Jan. 14, 1993, Federal Register (

"The reclassification of permit spaces allowed under paragraph (c)(7)(i) of the final rule recognizes that spaces such as mixers and material bins can have their hazards removed before entry, so that entrants are fully protected without the need for permits, attendants, or other features required by the full permit space program requirements given in paragraphs (d) through (k). Mixers can be locked out before it is entered for servicing or maintenance, removing the mechanical hazards. A material bin posing an engulfment hazard can be emptied before entry, thus removing that hazard. These are the types of spaces that can be made safe for entry following paragraph (c)(7)(i) of the final rule."

An entry may be necessary to initially perform testing and inspections to determine the hazards have been eliminated. This entry would require full compliance with the standard. A written certification must document the basis for the determination that all hazards in the space have been eliminated.

Alternate Entry
OSHA allows alternate entry procedures when the only hazard in a permit space is an atmospheric hazard that is controlled through continuous forced air ventilation. The alternate procedure, described in 1910.146(c)(5), allows entry without fulfilling the requirements outlined in the following paragraphs of the standard:
(d) Permit space program
(e) Permit system
(f) Entry permit
(h) through (j) Duties of authorized entrants, attendants, and entry supervisors
(k) Rescue and emergency services.

The standard refers to "continuous forced air ventilation" as a method to remove an atmospheric hazard from a confined space. Although negative pressure ventilation is not referenced in the rule, an LOI dated April 23, 1996, states that, in a sewer entry, negative pressure ventilation is not acceptable: "The Agency's position is that the required continuous forced air ventilation specified in paragraph (c)(5)(i)(B) means a delivery system or device that provides positive pressure for the space where the employees are working. A negative pressure application as indicated in the sketch provided is not acceptable."

Alternate entry procedures require pre-entry and periodic air monitoring along with the forced air ventilation.

The LOI dated Nov. 15, 1999, clarifies that the permit space may have no hazards other than an atmospheric hazard in order to use alternate entry procedures: "... 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."

As with permit space reclassification, an entry may be necessary to initially perform monitoring and inspections to determine it would be appropriate to use the alternate entry procedures. This entry would require full compliance with the standard. The employer must then develop data to support the conclusion that the space is safe for alternate entry procedures.

Providing Full Protection
Taking advantage of permit space reclassification or alternate entry procedures still requires following the standard's applicable requirements. There are other sources of information to help employers augment their programs.

A source of guidance on permit space entries is the recently revised voluntary consensus standard, Safety Requirements for Confined Spaces, ANSI Z117.1-2003, published by the American National Standard Institute (ANSI) in conjunction with the American Society of Safety Engineers. More information on ANSI standards is available on its Web site at or by calling its customer service representatives at 212-642-4900.

The National Institute for Occupational Safety and Health (NIOSH) has published a document, "Worker Deaths in Confined Spaces: A Summary of NIOSH Surveillance and Investigative Findings," DHHS (NIOSH) Publication No. 94-103, that serves as a stark reminder of how important safety considerations are during permit space entries. This document is available from the NIOSH Web site at, or it can be ordered by calling NIOSH at 800-356-4674.

Once any type of entry occurs, it is up to the employer to ensure the entry team is safe.

This article originally appeared in the August 2004 issue of Occupational Health & Safety.

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