This article is the first of a three-part series on Permit-Required Confined Spaces. In series one – General Requirements, we briefly cover the basics of permit-required confined spaces and their hazards. We share the Bureau of Labor Statistics’ most recent confined space data. We focused on Cal/OSHA’s General Requirements for Construction and General Industry and address those obligations for the employer, controlling contractor, employee representative, and the competent person. In series two – Permit-Required Confined Space Program, we systematically incorporated the requirements we covered in series one to create a Permit-Required Confined Space Program, including a Permitting Process and Entry Permit, resulting in a written and usable confined space program. Finally, in series three – Training, we drill down on the duties of Authorized Entrants, Attendants, Entry Supervisors, and Rescue and Emergency Services, followed by a true /false and multiple-choice test.

Note: Cal/OSHA’s general requirements for construction and Cal/OSHA’s general industry requirements are virtually the same. In fact, when reading both regulations, much of the writing is verbatim. The main differences are the article, sections, and subsection numbers. For instants, constructions General requirement’s Alternate Entry Procedures read: “1952(e) An employer may use the alternate procedures specified in Section 1952(e)(2) for entering a permit space only under the conditions outlined in Section 1952(e)(1)”; and the general industry General Requirement’s Alternate Entry Procedures read: “5157(5) An employer may use the alternate procedures specified in subsection (c)(5)(B) for entering a permit space under the conditions set forth in subsection (c)(5)(A).”

However, there are instances when a section may have a lengthier explanation or may not exist. In those circumstances, we have strived to explain the material to incorporate all relevant information fully.

What is a Confined Space?

A confined space (CS) is a space within a structure that has a restricted or limited way to enter and exit. It is large enough to allow an employee’s entire body to come inside and to do work. It is not designed for continuous human occupancy. Some examples of confined spaces are tanks, utility holes, boilers, furnaces, sewers, silos, hoppers, vaults, pipes, trenches, tunnels, ducts, bins, pits, etc.

you can see from the list above, confined spaces exist within many different structures and materials, varying in shapes and sizes, and found in every industry. Although silos and tunnels are easily recognizable as confined spaces, confined spaces often go unrecognized by employees. For example, employees may use ladders to enter and exit structures or may need to climb over or under objects or squeeze through portals to reach their work locations and never give it a second thought; these obstacles may result from entering a confined space.

Although many different structures may house confined spaces, the Division of Occupational Safety and Health Administration (Cal/OSHA) has classified only two types of confined spaces: non-permit-required confined space and permit-required confined space. As you may have guessed by the name, a non-permit space doesn’t require a permit.

Permit-Required Confined Space

So, what is a permit-required confined space? It is a space with the potential to have a dangerous atmosphere; for example, it may have a low amount of oxygen. The atmosphere may be flammable. It may have any other atmospheric condition that is immediately dangerous to life or health (IDLH). It may have material that could engulf an employee, such as grain, seeds, gravel, etc. Also, the permit space structural design may cause employees to become trapped or asphyxiated. For instance, the permit space may have inwardly converging walls, like silos or floors sloping downward, reducing to a lesser cross-section.

Confined Space Incident details

From 2011 to 2018, 1,030 workers died from occupational injuries involving a confined space. The annual figures ranged from a low of 88 in 2012 to a high of 166 in 2017. These data are from the Bureau of Labor Statistics, Census of Fatal Occupational Injuries (CFOI).

Certain types of events are linked closely to confined spaces. Trench collapses led to the deaths of 168 workers from 2011 to 2018. 135 of these workers were employed in the private construction industry.

Falls to a lower level accounted for 156 of the 1,030 confined spaces deaths during this period. The most common coded confined spaces in falls are silo, grain bin interiors (17); sewers, manholes, storm drains (16); and ditches, channels, trenches, excavations (15).

There were 126 cases of inhalation of a harmful substance in a single episode in a confined space over the 8 years. The most common types of inhaled gases were hydrogen sulfide (38 cases), carbon monoxide (23), methane (10), sewer gas (6), and solvents and degreasers (5). In addition to these inhalation cases, there were 39 cases of depletion of oxygen and 21 cases of drowning.

Ninety-eight workers were killed in incidents involving confined spaces due to engulfment in other collapsing materials. In total, 66 of these decedents were engulfed in cash grain crops or field crops.

Fires and explosions accounted for 58 cases, with explosions being the majority (46).

A total of 56 cases were attributable to being caught in running machinery. In 21 of these cases, the decedent was caught in a powered conveyor, most commonly a conveyor – screw, auger (15)

OSHA believes that about 224,000 workplaces in the United States have permit spaces that employ nearly 7.2 million workers, and about 2.1 million workers enter permit spaces each year. OSHA predicts that compliance with their regulations will avoid 53 worker deaths and injuries, 4,900 lost workday cases, and 5,700 non-lost time incidents yearly.

The U.S. Bureau of Labor Statistics, Injuries, Illnesses, and Fatalities, Published July 2020, (Accessed April 30, 2021)

General Requirements

Competent Person

Understandingly identifying confined spaces in the workplace ranks high on Cal/OSHA owners’ to-do list. In fact, it is the first regulation of Cal/OSHA’s 1952 – Construction General Requirements for confined spaces. It requires all owners to have a competent person (CP) to identify and classify all confined spaces at the worksite. Suppose the competent person classifies one or more confined spaces as a permit-required confined space. In that case, the competent person must inform all the employees working in the area by posting danger signs at the permit spaces’ entrance point. The signs should describe the permit space’s threats and the location.

NOTE: In the general industry, the responsibilities of the competent person are performed by the employer.

A sign reading DANGER — PERMIT-REQUIRED CONFINED SPACE, DO NOT ENTER” or using another similar language would satisfy a sign’s requirement.


After the competent person finishes the confined space hazard assessment, they will share their findings with the owner. Suppose there are permit spaces at the worksite. The owner must notify the employee’s representative of the permit spaces promptly. If the worksite is a multi-employer worksite, the owner must also inform the controlling employer. The information must include all permit-required confined spaces, locations, hazards, or reasons for the permit-required classification.

While posting permit-required confined space signs is a Cal/OSHA requirement for owners to protect employees, Cal/OSHA prohibits the owner from informing the controlling employer and the employee representative through posts. Owners must use other means, preferably via a direct written notification of the permit spaces’ existence.

Once an owner knows of permit spaces at their worksite and will not approve their employees to work in those spaces, they must take adequate steps to stop their workers from entering all permit spaces. If an owner decides a confined space at their workplace will never be entered by employees for any reason, the owner can forever seal the confined space and eliminate it. For example, welding the entryway shut is common practice to deny access to a confined space permanently.

On the other hand, if an owner determines their employees will enter into confined spaces, they must first develop a written confined space entry program that complies with Cal/OSHA’s section 1952 Construction standard, or if the owner works in the general industry, then the Cal/OSHA’s 5157 General Industry standard would apply. Both standards include but are not limited to training their employees on the dangers of those spaces and how they can protect themselves when working in permit-require confined spaces.

Before entry is allowed, the employer’s written program must be shared before and during entry operations for examination by all participating employees and their authorized representatives.

Non-Permit-Required Confined Space

All confined spaces should be considered permit-required confined spaces and should only become non-permit spaces after a competent person has downgraded them after performing a strict series of research, tests, and inspections. A competent person may use several ways to decide if a confined space should be downgraded to a non-permit space during a confined space assessment. For instance, if the conditions allow, a competent person could test and monitor the confined space atmosphere, or inspect for mechanical or biological hazards, or a competent person could use safety data sheets (SDS), schematics, and blueprints or a combination of all the above to determine a confined space status.

Suppose the competent person efforts determine the confined space has no potential hazardous atmosphere, and all the hazards within the confined space can be eliminated without entering the confined space through safe work practices; for example, preventing equipment from operating while workers are in the confined space through locking and tagging out equipment. In that case, the competent person can downgrade the permit-required confined space to a non-permit required confined space.

When downgrading a permit-required confined space to a non-permit required confined space, a competent person must verify in writing the above conditions have been met through certification. The certification will consist of the date, location of the space, and the competent person’s signature providing the certification. Suppose hazards arise in a confined space that was previously downgraded to a non-permit-required confined space. Each employee must immediately exit the confined space. The confined space must be reevaluated to learn how the hazard developed. The employer must carry out actions to protect employees from the hazard before any entry occurs. If the hazards were successfully eliminated, the non-permit entry could continue.

Alternate Entry Procedures 

Entry may be allowed into a permit-required confined space using alternate entry procedures 1952(e) construction standard and 5157(c) general industry standard. Suppose an owner or a contractor opted to qualify to use these procedures; in that case, if the employer can prove the only hazards in the permit space are atmospheric hazards and continuous forced air ventilation can control them, a written permit-required confined space program is not required.

The employer’s decision must be supported by data and confirm that all physical hazards in the confined space are isolated or eliminated via engineering controls. The only hazard created by the permit space is an actual or possibly hazardous atmosphere. The employer can prove that continuous forced air ventilation is enough to ensure that permit-space is safe for entry. If the ventilation system stops working, entrants can safely exit the space. The employer must develop monitoring and inspection data that support the employer’s decision and is made available to each employee who enters the permit space or to that employee’s authorized representative.

Suppose an initial entry of the permit space is necessary to obtain data required to monitor and inspect the permit-required confined space. In that case, the entry employer must postpone entry until creating a written confined space program. The program must comply with Sections 1953 through 1960, that includes: creating a permit-required confined space program, developing a written permitting process, issuing entry written permits, and training employees in the roles of the authorized entrant’s, the attendant, and the entry supervisor, and providing rescue and emergency services.

Once the owner or contractor meets the requirements for entering using alternate entry procedures, a certification must be completed before anyone can enter into the confined space. The certification consists of the date, location of the space, and the person’s signature providing the certification.

It is in the owner or contractor’s best interest to meet the alternate entry procedure requirements or the non-permit-required confined space. Both are much less stringent than the permit-required confined space. Suppose a contractor can neither downgrade a permit-required confined space to a non-permit-required confined space nor use alternate entry procedures. In that case, all Cal/OSHA’s requirements of permit-required confined spaces must be followed.

Cal/OSHA, Construction General Requirements, 1952(e)(1)(A) through (I)  (Accessed April 30, 2021).
Cal/OSHA, General Industry General Requirements 5157(5)(A) through (B)(8) (Accessed April 30, 2021).

Physical Hazards

Physical hazards cover the entire range of hazardous energy and its control. These hazards include mechanical, electrical, hydraulic energy, engulfment, communication problems, noise, and opening into the confined space.  In many cases, separating employees from physical hazards such as hydraulics, pneumatic lines, electrical components, mechanical equipment, or other stored energy forms that can potentially cause worker injuries and death within a confined space is impossible. It is essential to de-energize and lock out all electrical circuits and disable mechanical equipment before any work within a confined space can begin.

Inherent Hazards

Inherent hazards are related to specific equipment types and their electrical, thermal, chemical, mechanical, and other interactions. For instants, defective design, radiation generated by equipment, high voltage (shock or corona discharge and the resulting burns), the omission of protective features such as no preparation for grounding non-current-carrying conductive parts), high noise levels, low or high temperatures, high-pressure vessels and lines (rupturing with resultant release of fragments, fluids, gases, etc.). Inherent hazards usually cannot be eliminated without damaging the system or equipment or making them defective. Hence, importance must be placed on hazard control methods.

Induced Hazards

Many incorrect decisions and actions cause induced hazards during the actual construction process. Some examples are the omission of protective features, physical arrangements that may cause unintentional worker contact with electrical energy sources, oxygen-deficient atmospheres created at the bottom of pits or shafts, lack of safety factors in structural strength, and explosive atmospheres

Atmospheric Tests

Before an employee enters the space, the inside atmosphere must be tested with a calibrated direct-reading instrument, for oxygen content, flammable gases and vapors, and possible toxic air contaminants, in that order. All employees who enter the space or their authorized representatives shall be allowed to watch the pre-entry testing required by subsection 1952(e).

A hazardous atmosphere is not permitted within the space whenever employees are inside the space. Employees must not enter into a confined space until the forced air ventilation has removed any hazardous atmosphere. The forced air ventilation must ventilate the immediate areas wherever an employee is or will be present inside the space and shall continue until all employees have left the space. The forced air ventilation’ air supply must be from a clean source and must not add to the confined space’s hazards.

The employer must continuously monitor the confined space atmosphere unless the employer can prove continuous monitoring equipment is commercially unavailable or periodic monitoring is sufficient. The employer shall ensure that the monitoring equipment has an alarm that will notify all entrants of a specified atmospheric threshold achievement or that an employee will check the monitor with sufficient frequency to ensure that entrants have adequate time to escape. Periodic monitoring must be used when continuous monitoring is not required.

All monitoring must ensure that the continuous forced air ventilation is stopping the collection of atmospheric hazards. If employees discover a hazardous atmosphere during the entry, each employee must leave the space immediately. A competent person must reevaluate the confined space to learn how the hazardous atmosphere developed. The employer must take action to protect the workers from the hazardous atmosphere before a subsequent entry occurs.

When testing atmospheric hazards, qualified individuals who are thoroughly familiar with the testing device’s operating system, conditions, calibration information, and latest operating instruction; will use a calibrated direct-reading instrument to test the oxygen. The desired oxygen level is 20.9 percent, although Cal/OSHA allows 19.5 percent to 23.5 percent. Any reading below 19.5 percent is an oxygen-deficient atmosphere. Breathing oxygen-deficient air may result in asphyxiation or a worker’s death. On the other end of the spectrum, any reading above 23.5 percent is an oxygen-enriched atmosphere. An oxygen-enriched atmosphere is a serious potential fire hazard. Flammable materials will burn faster in an oxygen-enriched atmosphere.

The second atmospheric test the qualified individual will do is a combustible/flammable test. Combustible gas meters are oxygen dependent and will not work correctly in an oxygen-deficient atmosphere. Good flammable readings are below 10 percent of the lower explosive limit (LFL) for gases, vapors, mists, or combustible dust. Also, combustible gases and vapors are tested second because fire or explosion is usually more immediate and life-threatening.

The third atmospheric test a qualified individual will do is to test for toxic gases and vapors. Toxic gases and vapor readings are suitable when below the permissible exposure limit (PEL)/threshold limit value (TLV) or time-weighted average (TWA) of a substance. There are four ways toxins can enter the body: absorption, ingestion, inhalation, and injection.

Once testing is done, and the confined space class is known, the competent person will have gathered enough data to know the exact dangers of the space, including but not limited to which atmospheric hazards are present, such as low oxygen, flammable gas, toxic vapors, or explosive dust, and the most effective way to mitigate them, for example, by inerting the permit space or mechanical ventilation. The air volume to be moved and the fans’ size to move it, and the type of forced air ventilation method to be used (positive, negative, or both). The number of air exchanges needed to maintain a safe atmosphere and the most appropriate monitoring system for that specific type of permit-required confined space – personal, portable, or stationary monitors. The type of electrical components to be used in specific atmospheres – standard or intrinsically safe. The type and number of physical hazards existing in the permit space, and the engineering controls and safe work practices used to mitigate or eliminate them, such as double block and bleed, blanking or blinding, misaligning, lockout tagout, etc. The type of personal protective equipment (PPE) used in a specific atmosphere, such as a self-contained breathing apparatus (SCBA) or a level A: fully encapsulated suit.

Safe Entry

Safety decisions must be supported by data that prove the physical hazards are eliminated or isolated through engineering controls. The employer must document the data and make it available to each employer and their representative.

The employer must eliminate unsafe conditions before opening a confined space entry cover. Followed by the immediate installation of railings, barriers, or temporary covers will prevent an accidental fall through the opening and protect employees working inside from external objects entering the space.

The employer is required to ensure a safe means of entering and exiting the space. For instants, if an employer uses a hoisting system, it must be designed and manufactured for hoisting personnel. Also, a job-made hoisting system is permitted if approved for hoisting personnel by a registered professional engineer. The engineer’s approval of such a hoisting system must be in writing before use.

Employers must prove that the confined space is safe for entry and that section 1952 (e)(2) pre-entry requirements are complete via a written certification that includes the date, location of the confined space, and the person’s signature giving the certification. The employer must make the certification before entry and available to all employees entering the confined space or their authorized representatives.

If changes occur in the use or configuration of a non-permit confined space that could increase employees’ hazards or some indication the competent person may not have done the initial evaluation adequately; in that case, all entry employers must have a competent person reevaluate that space. If needed, reclassify it as a permit-required confined space.

Once an employer has classified a confined space as a permit-required confined space, only a competent person can reclassify it. The competent person must prove the confined space has no actual or possible hazardous atmosphere. All hazards within the space can be eliminated or isolated without entering into the confined space (unless it can be proven that eliminating a hazardous atmosphere without entry is infeasible). The competent person can reclassify a non-permit-required confined space as long as the non-atmospheric hazards remain eliminated or isolated.

Suppose employees must enter the confined space to isolate or eliminate the hazards. In that case, the entry employer is required to comply with Sections 1953 through 1960, which includes creating a permit-required confined space program, developing a written permitting process, issuing entry permits, and training employees in the duties of the authorized entrants, attendants, and entry supervisor, and providing rescue and emergency services.  If during a confined space entry, testing and inspection can demonstrate hazards within the permit space have been isolated or eliminated; in that case, the employer can reclassify the permit-required confined space to a non-permit-required confined space as long as the hazards remain isolated or eliminated.

The entry employer shall document the reason for deciding all of the hazards in a permit confined space have been eliminated or isolated via a written certification that includes the date, location of the space, and the person’s signature making the decision. The certification must be made accessible to all employees entering the confined space or to their authorized representative. If hazards arise inside a confined permit space once reclassified as a non-permit space under Section 1952(g), all employees in the confined space must exit. The entry employer must reevaluate the space and reclassify it as a permit-required confined space as appropriate, following all other relevant requirements of this standard.

Communication and Coordination

Before the entry procedure starts, the host employer shall give the following data to the controlling contractor if it has it. The location of each known permit-required confined space. The hazards or possible hazards in each confined space or the reason for classifying it as a permit-required confined space. Any precautions that the host employer or any past controlling contactor or entry employer has taken to protect employees within a permit-required confined space.

Before entry procedures begin, the controlling contractor must get the host employer’s information about the permit-required confined space risks and prior entry procedures and give the following data to each entity entering a permit-required confined space and any other entity at the workplace whose activities could predict the result in a hazard in the permit-required confined space: the data received from the host employer, any extra data the controlling contractor has about the topics listed in Section 1952(h)(1), and the precautions that the host employer, controlling contractor, or other entry employers completed for the security of employees in the permit space.

Before entry operations begin, all entry employers must get all of the controlling contractor’s data concerning the permit-required confined space dangers and entry procedures, and inform the controlling contractor of the permit-required confined space program the entry employer will follow, including any hazards likely to be found or created in each permit space.

The controlling contractor and all entry employers must coordinate entry procedures when more than one company are working within a permit space at the same time, or when conflicting activities within the space could predict hazardous results.

After Entry Operations:

The controlling contractor must question each entity that entered a permit-required confined space regarding the permit-required confined space program following any hazards found or created within the permit-required confined spaces during entry procedures. The entry employer must notify the controlling contractor promptly of the permit-required confined space procedure following any dangers found or created in the space(s) during entry operation, and the controlling contractor shall apprise the host employer of the information exchanged with the entry entities according to subsection (h)(5)

It should be noted Section 1952(h) states: Except a host employer or controlling contractor has or will have employees entering into a confined space, they are not required to enter any confined spaces to collect any data defined in Section 1952(h). Suppose there is no controlling contractor present at the worksite, the requirements for and the controlling contractor’s role in Section 1952 goes to the host employer or another employer who arranges other employers’ employees to perform work involving permit space entry.



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