Employees who work in confined spaces also face increased risk of exposure to serious physical injury from hazards such as entrapment, engulfment and hazardous atmospheric conditions.

Confinement itself may pose entrapment hazards, and work in confined spaces may keep employees closer to hazards such as machinery components than they would be otherwise. For example, confinement, limited access and restricted airflow can result in hazardous conditions that would not normally arise in an open workplace.

The terms “permit-required confined space” and “permit space” refer to spaces that meet OSHA’s definition of a “confined space” and contain health or safety hazards. For this reason, OSHA’s standard for confined spaces (29 CFR 1910.146) requires workers to have a permit to enter these spaces.

By definition, a confined space:
• Is large enough for an employee to enter fully and perform assigned work;
• Is not designed for continuous occupancy by the employee; and
• Has a limited or restricted means of entry or exit.

These spaces may include underground vaults, tanks, storage bins, pits and diked areas, vessels, silos and other similar areas.

By definition, a permit-required confined space has one or more of these characteristics: Contains or has the potential to contain a hazardous atmosphere;

Contains a material with the potential to engulf someone who enters the space;

Has an internal configuration that might cause an entrant to be trapped or asphyxiated by inwardly converging walls or by a floor that slopes downward and tapers to a smaller cross section; and/or contains any other recognized serious safety or health hazards.

OSHA’s Confined Space Standard

Employers in general industry must evaluate their workplaces to determine if spaces are permit spaces. If a workplace contains permit spaces, the employer must inform exposed employees of their existence, location and the hazards they pose. This can be done by posting danger signs such as “DANGER — PERMIT-REQUIRED CONFINED SPACE — AUTHORIZED ENTRANTS ONLY” or using an equally effective means.

If employees are not to enter and work in permit spaces, employers must take effective measures to prevent them from entering these spaces. If employees are expected to enter permit spaces, the employer must develop a written permit space program and make it available to employees or their representatives. Under certain conditions described in the standard, the employer may use alternate procedures for worker entry into a permit space. For example, if an employer can demonstrate with monitoring and inspection data that the only hazard is an actual or potential hazardous atmosphere that can be made safe for entry using continuous forced air ventilation, the employer may be exempted from some requirements, such as permits and attendants. However, even in these circumstances, the employer must test the internal atmosphere of the space for oxygen content, flammable gases and vapors, and the potential for toxic air contaminants before any employee enters it. The employer must also provide continuous ventilation and verify that the required measurements are performed before entry.

Written Programs

Any employer who allows employee entry into a permit space must develop and implement a written program for the space. Among other things, the OSHA standard requires the employer’s written program to:
• Implement necessary measures to prevent unauthorized entry;
• Identify and evaluate permit space hazards before allowing employee entry;
• Test atmospheric conditions in the permit space before entry operations and monitor the space during entry;
• Perform appropriate testing for the following atmospheric hazards in this sequence: oxygen, combustible gases or vapors, and toxic gases or vapors;
• Establish and implement the means, procedures and practices to eliminate or control hazards necessary for safe permit space entry operations;
• Identify employee job duties;
• Provide and maintain, at no cost to the employee, personal protective equipment and any other equipment necessary for safe entry and require employees to use it;
• Ensure that at least one attendant is stationed outside the permit space for the duration of entry operations;
• Coordinate entry operations when employees of more than one employer are working in the permit space;
• Implement appropriate procedures for summoning rescue and emergency services, and preventing unauthorized personnel from attempting rescue;
• Establish, in writing, and implement a system for the preparation, issue, use and cancellation of entry permits;
• Review established entry operations annually and revise the permit space entry program as necessary; and
• Implement the procedures that any attendant who is required to monitor multiple spaces will follow during an emergency in one or more of those spaces.

Controlling Hazards

The employer’s written program should establish the means, procedures and practices to eliminate or control hazards necessary for safe permit space entry operations. These may include:
• Specifying acceptable entry conditions;
• Isolating the permit space;
• Providing barriers;
• Verifying acceptable entry conditions; and
• Purging, making inert, flushing or ventilating the permit space.

Equipment for Safe Entry

In addition to personal protective equipment, other equipment that employees may require for safe entry into a permit space includes:
• Testing, monitoring, ventilating, communications and lighting equipment;
• Barriers and shields;
• Ladders;
• Retrieval devices;
• Detection of hazardous conditions.

If hazardous conditions are detected during entry, employees must immediately leave the space. The employer must evaluate the space to determine the cause of the hazardous atmosphere and modify the program as necessary.

When entry to permit spaces is prohibited, the employer must take effective measures to prevent unauthorized entry. Non-permit confined spaces must be evaluated when changes occur in their use or configuration and, where appropriate, must be reclassified as permit spaces.

A space with no potential to have atmospheric hazards may be classified as a non-permit confined space only when all hazards are eliminated in accordance with the standard. If entry is required to eliminate hazards and obtain data, the employer must follow specific procedures in the standard.

Informing Contract Employees

Employers must inform any contractors whom they hire to enter permit spaces about: • The permit spaces and permit space entry requirements;
• Any identified hazards;
• The employer’s experience with the space, such as knowledge of hazardous conditions; and
• Precautions or procedures to be followed when in or near permit spaces.

When employees of more than one employer are conducting entry operations, the affected employers must coordinate entry operations to ensure that affected employees are appropriately protected from permit space hazards. The employer also must give contractors any other pertinent information regarding hazards and operations in permit spaces and be debriefed at the conclusion of entry operations.

Entry Permits

A permit, signed by the entry supervisor, must be posted at all entrances or otherwise made available to entrants before they enter a permit space. The permit must verify that pre-entry preparations outlined in the standard have been completed. The duration of entry permits must not exceed the time required to complete an assignment.

Entry permits must include:

• Name of permit space to be entered, authorized entrant(s), eligible attendants and individuals authorized to be entry supervisors;
• Test results;
• Tester’s initials or signature;
• Name and signature of supervisor who authorizes entry;
• Purpose of entry and known space hazards;
• Measures to be taken to isolate permit spaces and to eliminate or control space hazards;
• Name and telephone numbers of rescue and emergency services and means to be used to contact them;
• Date and authorized duration of entry;
• Acceptable entry conditions;
• Communication procedures and equipment to maintain contact during entry; • Additional permits, such as for hot work, that have been issued authorizing work in the permit space;
• Special equipment and procedures, including personal protective equipment and alarm systems; and
• Any other information needed to ensure employee safety.

Cancelled Entry Permits

The entry supervisor must cancel entry permits when an assignment is completed or when new conditions exist. New conditions must be noted on the canceled permit and used in revising the permit space program. The standard requires that the employer keep all canceled entry permits for at least one year.

Worker Training

Before the initial work assignment begins, the employer must provide proper training for all workers who are required to work in permit spaces. After the training, employers must ensure that the employees have acquired the understanding, knowledge and skills necessary to safely perform their duties.

Additional training is required when:
• The job duties change;
• A change occurs in the permit space program or the permit space operation presents any new hazard; and
• An employee’s job performance shows deficiencies.

In addition to this training, rescue team members also require training in CPR and first aid. Employers must certify that this training has been provided.