1926 Subpart AA
An employer must implement measures necessary to prevent unauthorized entry into permit spaces. Employers can meet this requirement by locking or securing openings, posting warning signs, using physical barriers, and training employees about which spaces are permit-required. See 1926.1204(a).
An employer must identify and evaluate the hazards of permit spaces before employees enter them. This means performing a hazard assessment that documents atmospheric, physical, and engulfment hazards and using that information to decide controls and entry procedures. See 1926.1204(b).
Acceptable entry conditions must be specified by the employer and documented in the entry procedures or permit. Employers should define criteria such as minimum oxygen percentage, maximum allowable combustible gas levels, and permitted concentrations of toxic substances. See 1926.1204(c)(1).
Yes—an employer must provide each authorized entrant or that employee's authorized representative the opportunity to observe any monitoring or testing of permit spaces. Employers should allow observation of pre-entry and ongoing monitoring so entrants can verify testing was conducted. See 1926.1204(c)(2) and 1926.1204(e)(4).
Isolating a permit space means eliminating or controlling energy sources and physical hazards—such as locking out machinery, blanking or disconnecting pipes, and capping lines—so hazards inside the space cannot harm entrants. Controls should be documented and verified before entry. See 1926.1204(c)(3).
Employers must purge, inert, flush, or ventilate permit spaces as necessary to eliminate or control atmospheric hazards before and during entry. These engineering methods are required when hazardous atmospheres (e.g., toxic, oxygen-deficient, or combustible atmospheres) exist or could develop. See 1926.1204(c)(4).
Employers must determine that monitoring procedures will detect an increase in atmospheric hazard levels in enough time for entrants to safely exit if the ventilation system stops working. This may require continuous monitoring or alarm systems that alert entrants and attendants promptly. See 1926.1204(c)(5).
Employers must provide pedestrian, vehicle, or other barriers as necessary to protect entrants from external hazards. Examples include traffic barriers, protective fencing, or overhead shields to prevent vehicles or falling objects from endangering entrants. See 1926.1204(c)(6).
Employees may only enter or remain in a permit space with a hazardous atmosphere if the employer demonstrates that personal protective equipment (PPE) will provide effective protection for each employee in the space and the employer provides the appropriate PPE. Otherwise, the atmosphere must be eliminated or controlled before entry. See 1926.1204(c)(7).
Employers must eliminate any conditions—such as high pressure or energized systems—that could make it unsafe to remove an entrance cover. This prevents sudden releases or hazardous reactions when the cover is removed. See 1926.1204(c)(8).
Employers must provide required equipment at no cost, maintain it, and ensure proper use; this includes testing and monitoring instruments, ventilation, communications, PPE where engineering controls are insufficient, explosion-proof lighting, barriers, ladders, rescue and emergency equipment, and any other equipment necessary for safe entry and rescue. See 1926.1204(d) and the specific items 1926.1204(d)(1)–(9).
If employees use respirators during permit-space entry, employers must meet the respirator requirements in 1926.103, including selection, fit testing, medical evaluation, and maintenance. See 1926.1204(d)(4) and 1926.103.
Employers must provide lighting that meets the minimum illumination requirements in 1926.56, is approved for the ignitable or combustible properties of hazards present, and is sufficient for safe work and quick exit in an emergency. See 1926.1204(d)(5).
Employers must test permit space conditions to determine acceptable entry conditions before changing the space's natural ventilation and before entry is authorized to begin, unless isolation is infeasible (for example, in large or continuous systems). In infeasible cases, employers must perform pre-entry testing to the extent feasible and use continuous monitoring while entrants work. See 1926.1204(e)(1).
Employers may use periodic monitoring instead of continuous monitoring for an atmospheric hazard only if they demonstrate that equipment for continuously monitoring that hazard is not commercially available; otherwise continuous monitoring is required where entry is authorized in spaces that cannot be isolated. See 1926.1204(e)(1)(ii).
When testing for atmospheric hazards, employers must test first for oxygen, then for combustible gases and vapors, and then for toxic gases and vapors. Following this order ensures safe detection and response to the most immediately life‑threatening conditions. See 1926.1204(e)(3).
Authorized entrants or their authorized representatives must be given the opportunity to observe pre-entry and any subsequent testing or monitoring and must be provided immediately with the results of any testing conducted. Employers must share test results promptly and allow observation of the testing process. See 1926.1204(e)(4) and 1926.1204(e)(6).
Employers must provide at least one attendant outside the permit space for the duration of entry operations; attendants may be assigned to more than one permit space or stationed anywhere outside the space as long as they can effectively perform the duties in [1926.1209]. See 1926.1204(f) and 1926.1204(f)(1)–(2).
If an attendant is assigned to multiple spaces, the permit program must include means and procedures that enable the attendant to respond to an emergency affecting one or more permit spaces without being distracted from duties in [1926.1209]. This can include scheduling, communication protocols, and early-warning systems. See 1926.1204(g).
Employers must designate each person with an active role (authorized entrants, attendants, entry supervisors, testers/monitors), identify their duties, and provide the training required by [1926.1207]. The training must ensure competency to perform assigned tasks safely. See 1926.1204(h) and 1926.1207.
Employers must develop and implement procedures for summoning rescue and emergency services (including procedures for failed non-entry rescues), for rescuing entrants, for providing emergency services to rescued employees, and for preventing unauthorized rescue attempts. This plan must be documented and practiced as needed. See 1926.1204(i).
Employers must develop and implement a system for preparing, issuing, using, and canceling entry permits as required by the standard, including procedures for safely terminating entry operations under planned and emergency conditions. Permits document hazards, controls, authorized personnel, and duration of entry. See 1926.1204(j) and 1926.1205.
Employers must develop and implement procedures to coordinate entry operations, in consultation with the controlling contractor, so that employees of one employer do not create hazards that endanger employees of another employer. This includes sharing permits, hazard information, and agreed controls. See 1926.1204(k).
Employers must review the permit space program whenever measures may not protect employees (e.g., unauthorized entry, new hazards, incidents) and must review the program using canceled permits within 1 year after each entry; employers may perform a single annual review covering all entries in the 12‑month period. If no entry occurs during the period, no review is needed. See 1926.1204(m) and 1926.1204(n).
OSHA letters clarify that when respirators or other PPE are required during permit-space entry, employers must follow applicable respirator and PPE rules and perform hazard assessments. For respirators in construction asbestos work, OSHA explains selection and when supplied-air respirators are required in Respirator selection for asbestos work; for PPE hazard assessment requirements, OSHA confirms employers must assess hazards and provide written certification when PPE is required in PPE hazard assessment requirements. These interpretations apply when PPE and respirators are used to meet 1926.1204(d)(4).
If the atmosphere cannot be reduced below 10 percent of the lower flammable limit (LFL), the employer may enter only after inerting the space to render the entire atmosphere non-combustible, providing PPE for other atmospheric hazards (such as oxygen deficiency), and eliminating or isolating all physical hazards in the space. See 1926.1204(c) second paragraph.
Employers must provide an early-warning system that continuously monitors for non-isolated engulfment hazards when isolation is infeasible (for example, in a sewer or large continuous system) so entrants and attendants can be alerted and evacuated promptly. See 1926.1204(e)(1)(iii).