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Confined Space Awareness

What Exactly Is a Confined Space?

A confined space is any space that meets the following criteria:

  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 (for example, tanks, vessels, silos, storage bins, hoppers, vaults, and pits are spaces that may have limited means of entry.); and
  3. Is not designed for continuous employee occupancy.”1

Some additional examples of confined spaces include:

  • Manholes
  • Boilers
  • Sewers
  • Trenches
  • Tunnels
  • Ducts
  • Pits
  • Mills
  • Pipelines
  • Storage tanks

A non-permit required confined space is a space that “does not contain or, with respect to atmospheric hazards, have the potential to contain any hazard capable of causing death or physical harm.”2

A permit-required confined space is one that meets the three criteria above and also has one or more of the following:

  1. “Contains or has a potential to contain a hazardous atmosphere;
  2. Contains a material that has the potential for engulfing an entrant;
  3. Has an internal configuration such that an entrant could be trapped or asphyxiated by inwardly converging walls or by a floor which slopes downward and tapers to a smaller cross-section; or
  4. Contains any other recognized serious safety or health hazard.”3

OSHA/VOSH has developed a Permit-required Confined Space Decision Flow Chart to help identify permit-required spaces. Once these spaces have been identified, signs with this or similar language are to be posted:DANGER

A program should also be implemented and should identify several key components such as hazard identification; acceptable entry conditions; elimination or control of atmospheric hazards; confined space isolation steps to protect entrants and bystanders; testing, ventilation, and communication equipment; and identification of work practices, engineering controls, and any necessary personal protective equipment (PPE). Examples of permit-required confined space programs can be found at OSHA/VOSH 29 CFR 1910.146 Appendix C.

Confined Space Hazards

When entering and working in a confined space, several hazards may be encountered and some may even be created:

  • Oxygen deficient or enriched atmospheres
  • Flammable atmospheres
  • Toxic atmospheres
  • Temperature extremes
  • Engulfment hazards
  • Entrapment hazards
  • Slick/wet surfaces
  • Falling objects
  • Noise
  • Awkward space configuration

If the identified hazard cannot be eliminated, the worker must be protected from exposure prior to allowing entry.

Roles and Duties

There are several individuals who play a significant role in successful confined space entries and programs. These individuals should be identified and trained appropriately prior to performing a confined space entry.

Authorized Entrant(s)– authorized by the employer to enter the permit space.

Attendant(s)– stationed outside of the permit space, monitors authorized entrants for the duration of the operation to ensure conditions are acceptable throughout the duration of the entry, performs attendant duties outlined in the agency’s permit space program.

Entry Supervisor(s) – employer, foreman, crew chief, or other supervisory individual; determines if entry conditions are acceptable at a permit space prior to entry. Authorizes, oversees, and terminates entry. Responsible for the permit process. May also serve as the attendant or authorized entrant. Duties may be passed to other individuals during the course of the operation.

Making the Space Safe for Entry

Prior to entering the space, the entry supervisor should determine if the conditions are acceptable for entry. It may be necessary to ventilate with forced air before testing begins. Additionally, the space should be isolated to protect entrants from external hazards. External hazards include items falling or being thrown into an open manhole and automobile exhaust or gas powered engine fumes/vapors drawn into the space because the source is too close to either the ventilation system or the entrance of the space.

Atmospheric testing should be conducted for oxygen levels, combustible gases/vapors, and toxic gases/vapors. A multi-gas monitor is often used for this task, testing the top, middle, and bottom of the space for atmospheric hazards since chemicals may vary in weight. Methane, for example, is lighter than air; carbon monoxide is the same as air; and hydrogen sulfide is heavier than air. Testing at all three levels helps ensure proper detection of the potential hazards. OSHA recommends testing oxygen levels first, then combustible gases/vapor, and lastly toxic gases/vapors.

Confined Space PPE

When preparing to enter a confined space, a PPE hazard assessment should be conducted. The assessment should identify what hazards the entrant may encounter to determine the appropriate level of PPE. Examples of some PPE routinely used in confined space entry include:

  • Fall/rescue protection-harness, lanyard, tripod
  • Hardhats
  • Respiratory protection-either air-purifying or air-supplying respirators
  • Face shields
  • Safety glasses/goggles
  • Hearing protection- earplugs, earmuffs, or both
  • Body protection- Tyvek suits, aprons, long pants, long sleeves
  • Gloves-work gloves, chemical gloves, dielectric gloves
  • Protective footwear- rubber boots, work boots, slip-resistant soled shoes

Permit Information

A permit system should be developed and used each and every time a permit-required confined space is to be entered by an agency employee. Consistently using the permit system increases the likelihood that the entry will be successful and employees will avoid preventable injuries. The permit should include specific information:

  • The permit space to be entered
  • The purpose of the entry
  • The date and the duration of the permit
  • Authorized entrants by name
  • Attendant names
  • Supervisor’s name and signature
  • Identified hazards
  • Methods used to eliminate the hazards
  • Acceptable entry conditions
  • Results of tests and tester’s initials
  • Rescue and emergency services information
  • Communication procedures
  • PPE & other equipment

An example of a confined space permit (with pre-entry checklist) can be found at OSHA/VOSH 29 CFR 1910.146 Appendix D.

Training Requirements

All affected employees must be trained before they are assigned the task of entering a confined space. In addition to identifying hazards that employees may encounter while performing confined space entry, the training should include a review of the program and the permitting system. It is important that the employees know the agency’s policy for confined space rescue. If personnel are not trained to perform rescue, instruct them to contact emergency personnel and wait for their arrival to prevent multiple injuries or fatalities.

A supervisor or supervising individual should monitor the procedures periodically to determine if there are any deviations from the permit space entry procedures. If deviations are identified, re-training is necessary. Re-training should also occur if the characteristics of the permitted space have changed or if the operation to be performed presents a different hazard to the employee that was not covered in previous training.

In all cases, the training must be certified and must include each employee’s name, signature and initials of the trainers, and the date of the training.


The critical components to remember to protect employees entering permit-required spaces is to first identify the hazards, try to eliminate them by providing engineering controls, adjusting work practices, and if the hazard is still present, providing appropriate PPE. Next, develop a program and make sure all employees’ roles are identified and they are trained on their responsibilities. Implement a confined space permit system to include monitoring the space and enforce the consistent use of the permit. Finally, communicate your agency’s procedures for confined space rescue and who to contact in case of an emergency to employees. With these measures in place, employees are given the tools necessary to perform the confined space entry safely and without injury.

1 Occupational Safety and Health Administration. (n.d). Permit-required confined spaces- 1910.146. Retrieved May 12, 2006 from,

2 Ibid

3 Ibid


Occupational Safety and Health Administration (2/23/04). Confined Space Hazards and Possible Solutions. Retrieved May 24, 2006 from,

Occupational Safety and Health Administration (2/23/04). Confined Space OSHA Standards. Retrieved May 24, 2006 from,

Occupational Safety and Health Administration (2/23/04). Confined Spaces Additional Information. Retrieved May 24, 2006 from,

Sullivan, John (n.d.). “Confined Space Awareness: General Industry Standard-29 CFR 1910.146” training program. Department of Human Resource Management- Workers’ Compensation Services.

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