Confined Space Entry Procedure: OSHA Permits, Roles, and Rescue

The OSHA confined space entry procedure requires an employer to classify the space, isolate every hazard, test the atmosphere in a set sequence, issue a written entry permit signed by a qualified supervisor, assign trained entrants and an outside attendant, monitor conditions continuously, and have rescue capability standing by before the first worker crosses the opening. Two standards set these rules: 29 CFR 1910.146 for general industry and 29 CFR 1926 Subpart AA for construction. They share the same core framework, with construction adding a competent person and stricter coordination requirements on multi-employer worksites.

When the Procedure Applies

OSHA treats a space as confined when three things are true at once. It is large enough for a worker to enter and do work, its entry or exit is limited or restricted, and it is not designed for continuous occupancy.¹ Tanks, manholes, vaults, boilers, silos, large ductwork, some crawl spaces, and deep trenches with limited access all qualify.

A confined space with no serious hazards is a non-permit space. It still needs basic precautions but does not trigger the full permit procedure. A space becomes permit-required the moment one or more of these hazards appears or could appear:

A hazardous atmosphere: oxygen below 19.5% or above 23.5%, flammable gas or vapor at or above 10% of the lower flammable limit, combustible dust at dangerous concentrations, or toxic substances above permissible exposure limits.²
Engulfment potential from loose material like grain, sand, or liquid.
An entrapment configuration, meaning walls that converge inward or a floor sloping into a tighter section.
Any other recognized serious hazard, such as unguarded machinery, exposed electrical parts, extreme heat, or chemical exposure.

A permit space can be reclassified to non-permit only if it has no atmospheric hazards and every other hazard can be eliminated without anyone entering. Controlling an atmospheric hazard with forced-air ventilation does not count as eliminating it: if the blower shuts off and the hazard returns, the hazard was controlled, not removed.²

The Written Program Comes First

Before any permit entry, an employer whose workers will enter permit spaces must develop and implement a written confined space program. That document has to cover how the employer will prevent unauthorized entry, how hazards will be identified and evaluated before entry, and the procedures for isolating the space, controlling atmospheric hazards, and providing required equipment. It must also address ventilation failure, protection from external hazards like vehicle traffic, and how rescue will be summoned.³

Atmospheric monitors, ventilation, communications equipment, PPE, lighting, and rescue gear must be provided at no cost to workers. The program must be available to employees and their representatives before and during entry.

Isolate the Space and Test the Atmosphere

Preparation starts with a hazard assessment of the specific space. Every potential danger gets cataloged, and those findings drive the controls that follow.

Isolation comes next. Lockout/tagout de-energizes mechanical and electrical equipment. Blanking or blinding pipelines physically blocks the flow of hazardous materials. Mechanical linkages are disconnected. Once the space is isolated, atmospheric hazards are addressed through purging, ventilation, or both to bring readings within safe limits.²

Atmospheric testing follows a fixed order, and the order matters. Oxygen is tested first, because most combustible gas meters need adequate oxygen to read accurately. Flammable gases and vapors are tested next, because fire and explosion pose the most immediately life-threatening risk. Toxic gases such as carbon monoxide and hydrogen sulfide are tested last.⁴

Acceptable readings are oxygen between 19.5% and 23.5%, flammable gas well below 10% of the lower flammable limit, and toxic substances below OSHA’s permissible exposure limits. Test at the top, middle, and bottom of the space. Gases stratify by density, and a safe reading at the opening can hide a heavier-than-air toxic gas pooling below. Use a calibrated, direct-reading instrument, and let any entrant or their representative observe the testing.

What the Entry Permit Must Contain

The entry supervisor completes and signs the permit before anyone enters. OSHA requires the permit to include at least:⁵

Space location, purpose of entry, date, and authorized duration.
Names of authorized entrants (or a tracking system reference), the attendant, and the entry supervisor, with the supervisor’s signature.
Known hazards, isolation and control measures, and acceptable entry conditions.
Initial and periodic atmospheric test results, with tester name and time of each test.
PPE, testing instruments, communication devices, alarms, and rescue equipment required for the entry.
Available rescue services and how to summon them.
Communication procedures between entrants and the attendant.
Any additional permits issued for work inside the space, such as a hot work permit.

The completed permit is posted at the entry point so every worker can see it during the operation. When the work is finished, or a prohibited condition develops, the entry supervisor cancels the permit. Canceled permits must be retained for at least one year so the employer can review the program and identify problems.⁶

Who Fills Each Role

Every permit entry requires at least three defined roles, and one person cannot hold two of them at the same time during an active entry. Each person must be trained for their specific role.

Authorized Entrant

The entrant is the worker who goes in. Before entering, the entrant must understand the hazards and how exposure could affect their body and behavior. Entrants use the provided equipment properly, stay in communication with the attendant, alert the attendant to any warning sign or prohibited condition, and evacuate immediately when told.²

Attendant

The attendant stays outside the space for the entire entry and does not enter under any circumstances. That is the rule, without exception. The attendant tracks how many workers are inside, monitors conditions, keeps unauthorized people away, and serves as the single point of contact for calling emergency services. If a hazardous condition develops, the attendant orders immediate evacuation.¹

Entry Supervisor

The entry supervisor has overall authority. This person verifies that pre-entry checks are complete, that acceptable conditions exist, and that rescue services are available before signing the permit. If conditions deteriorate, the supervisor terminates the entry and cancels the permit. Whoever fills this role must be qualified to evaluate the specific hazards of the space.²

Competent Person (Construction Only)

On construction sites, a competent person must identify every confined space where employees could work, determine which are permit-required, reevaluate spaces when conditions change, and handle reclassification decisions.³

Continuous Monitoring and Evacuation

Once the entry supervisor confirms that test results match the acceptable conditions on the permit, the entrant may proceed. Atmospheric monitoring continues for the entire duration of the entry, because conditions inside can shift rapidly from the work itself, from chemical reactions, or from activity happening outside the space. If a monitor alarms, if an entrant shows signs of exposure, or if any prohibited condition develops, the attendant orders evacuation. No one re-enters until the space has been fully re-evaluated.

Rescue Must Be Ready Before Entry Starts

The emergency plan has to be confirmed before the permit is signed. Rescue capability must be tested, available, and able to deploy within a timeframe appropriate for the identified hazards.

OSHA’s preferred approach is non-entry rescue. Every entrant wears a chest or full-body harness with a retrieval line attached at the center of the back near shoulder level, above the head, or at another point that keeps the profile small enough for removal. Wristlets may be used only if a harness is infeasible or would create a greater hazard. The retrieval line runs to a mechanical device or fixed anchor outside the space. For vertical spaces deeper than five feet, a mechanical retrieval device is required.³ Non-entry rescue is required unless retrieval equipment would increase risk or fail to help given the internal layout.²

When entry rescue is necessary, the employer must arrange a designated rescue service capable of responding in time. Team members must be trained and proficient, and at least one member must hold current certification in first aid and CPR. Rescue teams must practice permit space rescues at least once every twelve months using dummies, manikins, or actual persons in the specific permit spaces or in spaces that match them in opening size, layout, and accessibility. The annual practice is waived only if the team performed an actual rescue in the same or a similar space within the past twelve months.⁷

When the Alternate Procedure Is Allowed

Not every permit space requires the full permit process. OSHA allows a streamlined alternate procedure when two conditions are both met: the only hazard is an actual or potential hazardous atmosphere, and continuous forced-air ventilation alone is enough to keep the space safe. If any engulfment, mechanical, or other non-atmospheric hazard exists, the alternate procedure is off the table.²

Under the alternate procedure, the employer still tests the atmosphere before entry in the standard oxygen-flammable-toxic sequence with a calibrated instrument. No one may be inside while a hazardous atmosphere exists. Forced-air ventilation runs continuously and is directed to eliminate the atmosphere before the first worker enters. The opening is guarded against falls and dropped objects. The monitoring data supporting the decision to use this procedure must be documented and available to employees. The alternate procedure removes the formal permit, the designated attendant, and the retrieval system requirements, but only when ventilation alone can be shown to control the hazard.

Hot Work Adds a Second Permit

Welding, cutting, grinding, and any other work that produces sparks or flame inside a confined space needs additional precautions on top of the entry permit. A separate hot work permit is typically required, and that authorization must be noted on the confined space entry permit itself.⁵

Hot work cannot begin until a designated person has tested the atmosphere and confirmed it is not hazardous. Containers or equipment that previously held flammable substances must be cleaned, filled with water, or ventilated and re-tested before any spark-producing work. Hot work is prohibited in any flammable or potentially flammable atmosphere.⁸ Because the work itself generates fumes and consumes oxygen, continuous monitoring is especially important during these operations.

Coordination on Multi-Employer Sites

Confined space work on construction sites often involves several employers, and OSHA requires explicit coordination. The host employer and controlling contractor must discuss confined spaces and their hazards with entry employers before and after entry operations.⁹ A generator running near a confined space opening can push carbon monoxide into the space and overwhelm the entrants inside, and coordination is what catches that kind of externally introduced hazard. Each employer shares information about the hazards they know of, the precautions they have taken, and any conditions they have observed. After entry, the parties debrief so any problems inform future entries in the same space.

Training and Records

Every worker whose duties involve confined space entry must be trained before their first assignment. The training must give them the knowledge and skills for their specific role.² Under the construction standard, training must be delivered in a language and vocabulary the employee can understand.³

Retraining is required when a worker’s duties change, when permit space operations change in a way that introduces unfamiliar hazards, or when the employer has reason to believe a worker’s knowledge or performance has fallen short. Training must also cover the dangers of attempting an unauthorized rescue for workers not designated as entry rescuers. The employer certifies completion and keeps records showing each employee’s name, the trainer’s name, and the training dates, available for inspection by employees and their representatives.

Penalties for Skipping the Procedure

OSHA actively enforces the confined space standards. As of January 2025, the maximum fine for a serious violation is $17,004 per instance. Willful or repeated violations carry a maximum of $165,514 each.¹⁰ Citations stack quickly because a single poorly managed entry can involve several separate failures: no written program, no permit, no atmospheric testing, no training, no rescue equipment. Each is its own citation, and an employer who bypasses the procedure for what looks like a routine entry can face six-figure totals before the work even begins.

1
Occupational Safety and Health Administration. 1926.1202 – Definitions
2
Occupational Safety and Health Administration. 29 CFR 1910.146 – Permit-Required Confined Spaces
3
eCFR. 29 CFR Part 1926 Subpart AA – Confined Spaces in Construction
4
Occupational Safety and Health Administration. 1910.146 App B – Procedures for Atmospheric Testing
5
GovInfo. 29 CFR 1926.1206 – Entry Permit
6
U.S. Department of Labor. elaws – OSHA Confined Spaces Advisor
7
Occupational Safety and Health Administration. 1926.1211 – Rescue and Emergency Services
8
Occupational Safety and Health Administration. 1917.152 – Welding, Cutting and Heating (Hot Work)
9
Occupational Safety and Health Administration. Confined Spaces in Construction – Frequently Asked Questions
10
Occupational Safety and Health Administration. OSHA Penalties