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Confined Space Program

Pothole in the street is opened up with a ladder entering into it and yellow and black striped protective railing surrounds the area

Confined Space Program Summary

This program establishes guidelines and procedures for confined space entry.

This program applies to all departments that have confined spaces in their work area, or where employees must enter confined spaces to perform work. A confined space may have poor air quality due to lack of natural ventilation, a potentially toxic or hazardous atmosphere, or other serious hazards that must be considered. Personnel entering confined spaces at Virginia Tech must be trained on confined space hazards, the assessment process, and hazard controls. Only authorized personnel may enter confined spaces. An Assessment Form must be completed by the supervisor in charge prior to personnel entering into any confined space.

Employers are required by OSHA to evaluate the workplace to determine if there are permit-required confined spaces present. Departments should work with Environmental, Health and  Safety to determine appropriate entry protocols, as necessary. Employees must be informed of such spaces in the work area by posting danger signs, or by any other equally effective means (i.e. awareness training). Departments are responsible for providing and applying appropriate signs in accordance with OSHA regulations. Example: "DANGER: Confined Space - DO NOT ENTER."

Danger, Confined Space, Authorized Personnel Only sign

Where departments decide that employees will not enter permit spaces, effective measures must be taken to prevent inadvertent and unauthorized entry into the space. Unauthorized entry into a confined space is strictly prohibited due to the potential for death, incapacitation, injury or acute illness. Employees who work in the vicinity of, but who will not enter, confined spaces must complete awareness level training.

Departments with personnel who need to enter confined spaces must have a competent person overseeing entry activities, including assessing the conditions of the space prior to entry, performing air monitoring, and ensuring appropriate hazard controls have been implemented and are effective, and giving approval for entry. Supervisors, personnel entering the confined space, or serving as an attendant must attend Confined Space Entrant/Attendant/Supervisor level training. 

If the space has been determined to be permit-required, then the entry must be coordinated with Environmental Health & Safety.

Confined Space Online Program


Environmental, Health & Safety developed the Confined Space Program to protect employees from hazards that may be encountered during entry into a confined space. This program is intended to assure that:

  • Workers who are required to enter confined spaces are properly trained and supervised.
  • Procedures are in place to prevent employee exposure to hazardous atmospheres or conditions related to confined spaces.

Key components of this program include:

  • Surveying workplaces to identify confined spaces.
  • Posting signs to assist with recognizing confined spaces on university properties.
  • Training individuals who will perform work associated with confined spaces.
  • Developing written entry practices and procedures. 
  • Implementing a permit system to monitor entry into confined spaces with uncontrolled hazards.

This program applies to all departments that have employees who work in confined spaces. Examples of confined spaces at Virginia Tech include, but are not limited to:

  • Steam tunnels;
  • Electrical vaults;
  • Feed bins;
  • Silos;
  • Boilers and associated vessels;
  • Storage tanks;
  • Pits (elevator, manure, coal, etc.); and/or
  • Trash compactors


Feed bins on a farm

Note: Spaces that do not meet the definition of a confined space, do not fall within the scope of this program. This program does not apply to spaces that may meet the definition of a confined space, but have another OSHA standard that covers it, such as Excavations (1926 Subpart P), Underground Construction, Caissons, Cofferdams, and Compressed Air (1926 Subpart S), or Diving (1926 Subpart Y). 

All spaces on campus are assumed to be permit-required until they are assessed and determined to be non-permit confined spaces. Use the Confined Space Assessment Form to identify existing and potential hazards, and establish appropriate means and methods to eliminate or control the hazards (if applicable) at the time of entry.

This program has been designed to comply with OSHA standard 29 CFR 1910.146, Permit-Required Confined Spaces, and 29 CFR 1926 Subpart AA, Confined Spaces in Construction.


Environmental Health & Safety will monitor the overall effectiveness of the program, provide centralized recordkeeping, review confined spaces upon request, assist with atmospheric testing and equipment selection as needed, provide employee training, provide feedback to departments for improvement, and provide technical assistance, where requested. 

Completed Assessment Forms should be forwarded to Environmental Health & Safety quarterly for review and recordkeeping. Feedback will be provided to the department if there are corrections or improvements that need to be made.

Each department must be aware of university guidelines relating to confined spaces. The department must ensure:

  • Confined space in the work area are identified (i.e. marked with appropriate "Danger - Permit-Required Confined Space, Do Not Enter" signage) and evaluated (if they will be entered),
  • Departmental employees who work in or around confined spaces receive appropriate training as indicated in this program,
  • Effective measures are taken for permit-required confined spaces that employees will not enter to prevent unauthorized entry.

Entry supervisors shall assure that the procedures described in this program are followed, and ensure that employees entering confined spaces are properly trained and equipped to perform their duties safely. The entry supervisor shall complete the Assessment Form as specified in this program, ensure entry conditions are satisfactory, and terminate the entry upon completion of work.

The designated confined space entry supervisors shall: 

  • Know the hazards that may be faced during entry, including information on the mode, signs or symptoms, and consequences of the exposure;
  • Verify, by completing the appropriate fields on the Assessment Form, that all tests specified on the form have been conducted and that all procedures and equipment specified on the form are in place before signing the form and permitting entry to begin;
  • Coordinate "permit-required" confined space entries with Environmental Health & Safety and ensure rescue services are available;
  • Verify that means for summoning rescue services are operable;
  • Removes unauthorized individuals who enter, or who attempt to enter, the space during entry operations;
  • Ensures that entry conditions remain consistent with the terms identified on the Assessment Form and that acceptable entry conditions are maintained; 
  • Terminate the entry and cancel the form when work is completed; and 
  • Forward all completed Assessment Forms to Environmental Health & Safety quarterly for review and recordkeeping. 

Note: An entry supervisor also may serve as an attendant, or as an authorized entrant, as long as that person is trained and equipped to do so. The duties of entry supervisor may be passed from one individual to another during the course of an entry.

Man entering a small portal

Personnel entering confined spaces may only do so after receiving appropriate training.

Authorized entrants must: 

  • Know the hazards that may be faced during entry, including information on the mode, signs or symptoms, and consequences of the exposure.
  • Properly use any equipment associated with the entry, such as testing and monitoring equipment, ventilation equipment, communications equipment, personal protective equipment, lighting, barriers and shields, ladders, rescue, and emergency equipment, and other equipment necessary for safe entry into, exit from, and rescue from permit spaces.
  • Communicate with the attendant as necessary to enable the attendant to monitor entrant status and to enable the attendant to alert entrants of the need to evacuate the space.
  • Alert the attendant whenever warning signs or symptoms of exposure to a dangerous situation are recognized, a prohibited condition is recognized, and exit the space if indicated.
  • Exit the space as quickly as possible whenever: 
    • An order to evacuate is given by the attendant or entry supervisor,
    • There is any warning sign or symptom of exposure to a dangerous situation,
    • The entrant detects a prohibited condition; or
    • An evacuation alarm is activated.
Man looking into small portal

Personnel designated as attendant by the entry supervisor must:

  • Know the hazards that may be faced during entry, including information on the mode; signs or symptoms, and consequences of the exposure.
  • Know the possible behavioral effects of hazard exposure in authorized entrants. 
  • Continuously maintain an accurate count of authorized entrants in the space and ensure that the means used to identify authorized entrants accurately identifies who is in the space.
  • Remain outside the space during entry operations until relieved by another attendant.
  • Communicate with authorized entrants as necessary to monitor entrant status and to alert entrants of the need to evacuate the space.
  • Monitor activities inside and outside the space to determine if it is safe for entrants to remain in the space and order the authorized entrants to evacuate the space immediately under any of the following conditions:
    • The attendant detects a prohibited condition;
    • The attendant detects behavioral effects of hazard exposure in the authorized entrants;
    • The attendant detects a situation outside the space that could endanger the authorized entrant; or
    • The attendant can not effectively and safely perform the requirements of this section.
  • Summon rescue and other emergency services as soon as the attendant determines that authorized entrants may need assistance to escape from permit space hazards.
  • Warn unauthorized persons to stay away from the confined space, advise the unauthorized persons that they must exit immediately if they have entered the space, and inform the authorized entrants and the entry supervisor if unauthorized persons have entered the space.
  • Perform non-entry rescues as specified herein.
  • Perform no other duties that might interfere with the attendant's primary duty to monitor and protect the authorized entrants.

Contractors performing work in university-owned confined spaces must coordinate their work with the contracting university department or Environmental Health & Safety, as appropriate. Virginia Tech remains the Host Employer for non-capital projects; however, the general contractor typically serves as the property owner/manager for capital projects (i.e. host employer). Contractors and subcontractors must comply with all local, state, and federal safety requirements for confined space entry, including having a Confined Space Program when work involves confined space entry. Refer to the Safety Requirements for Contractors and Subcontractors Program for more information.

Training Information

Employees entering confined space, serving as an attendant, or supervising employees performing such tasks must complete entrant/attendant/supervisor-level training. If there are confined spaces in the work area that are accessible by unauthorized personnel, awareness level training must be completed.

Persons that work around, but not in, confined spaces must receive awareness level training, which includes such topics as:

  • Definition and identification of confined spaces;
  • Hazards associated with confined spaces;
  • Authorized entry criteria; and
  • Basic requirements of this program.

Personnel who enter confined spaces must attend entrant level training that includes:

  • Awareness training as described above;
  • Hazardous atmosphere recognition and use of atmospheric testing devices, including information on the mode, signs, symptoms, and consequences of exposure;
  • The use of personal protective equipment including rescue harnesses, respiratory protection, etc.,
  • Entry conditions and related precautions;
  • First aid/CPR/AED training for designated attendants and rescue personnel; 
  • Space classification and reclassification criteria;
  • Recognition of warning signs, symptoms of exposure, and detection of prohibited conditions;
  • Evacuation requirements;
  • Emergency and non-entry rescue methods, and procedures for calling rescue services; and
  • Specific responsibilities and duties for each role (entrant, attendant, supervisor).


All confined spaces at Virginia Tech are assumed to be permit-required unless evaluated prior to entry and determined to be non-permit required spaces. The presence of any of the hazards listed below deems the confined space a permit-required confined space and actions must be taken to eliminate or isolate the hazard before entering in order to declassify it. If a hazard cannot be eliminated or isolated, the space is considered "permit-required" and Environmental Health & Safety should be contacted for review and recommendations.

Hazardous atmospheres are the leading cause of deaths in confined spaces. This condition is difficult to detect without proper air monitoring equipment. The lack of natural ventilation, the presence of stored materials (such as chemicals), or the work process to be performed in a confined space can result in one or more of the following hazardous atmospheres. If the condition exists or has the potential to exist, it must be eliminated or isolated prior to entry.

  • Flammable gas, vapor, or mist in excess of 10 percent of its lower flammable limit (LFL/LEL). Sources of flammable gases may come from leaking acetylene hoses, methane gas, chemicals or other products used in the space. If the LEL shows a percentage less than 10 percent, but greater than 1 percent or 2 percent, it would be prudent to investigate possible sources prior to entry and take necessary precautions since conditions can change suddenly.
  • Airborne combustible dust at a concentration that meets or exceeds its lower flammable limit (LFL) can result in an explosion. This concentration may be approximated as a condition in which the combustible dust obscures vision at a distance of 5 feet or less.
  • Atmospheric oxygen concentration:
  • The atmospheric concentration of any substance for which a dose or a permissible exposure limit (PEL) is published by OSHA. Note: An atmospheric concentration of any substance that is not capable of causing death, incapacitation, impairment of the ability to self-rescue, injury, or acute illness due to its health effects is not covered by this definition. Common toxic substances found in confined spaces include:
  • Any other atmospheric condition that is immediately dangerous to life or health (IDLH). For air contaminants for which OSHA has not determined a dose or permissible exposure limit (PEL), other sources of information, such a Safety Data Sheets that comply with the Hazard Communication Standard, published information, and internal documents can provide guidance in establishing acceptable atmospheric conditions.

Engulfment means the surrounding and effective capture of a person by a liquid or finely divided (flowable) solid substance that can be aspirated to cause death by filling or plugging the respiratory system, or that can exert enough force on the body to cause death by strangulation, constriction, crushing, or suffocation. Examples include grains, sand, soil, rock salt, etc. If the condition exists or has the potential to exist, it must be eliminated or isolated prior to entry.

Man in grain bin

The space could have an internal configuration that could trap or asphyxiate an entrant, e.g. inwardly converging walls or a floor that slopes downward and tapers to a smaller cross-section, which is common with feed bins (as shown). The atmosphere at this bottom cross-section may be hazardous, or there may be mechanical hazards (e.g. augers) that could seriously injury or incapacitate the entrant. If the condition exists or has the potential to exist, it must be eliminated or isolated prior to entry.

Feed bin with narrow bottom
Man welding in tank

Other serious hazards that may pose an immediate danger to life or health must also be considered prior to entry. The determination of whether the resulting exposurepr to a hazard in a confined space would impair the person's ability to perform self-rescue is the aspect that must be considered and addressed prior to entry. Examples may include:

Hazards must be evaluated by the entry supervisor and necessary controls implemented to eliminate or isolate the existing or potential hazard(s) in order to reclassify the space from a permit-required confined space to non-permit-required confined space. 


The departmental Entry Supervisor (or designee) must assess the confined space conditions prior to entry, using the Assessment Form, to determine if there are permit-required conditions that cannot be eliminated or effectively controlled. A detailed explanation of properly filling out the form, and posting requirements, are covered in Confined Space Entrant/Attendant/Supervisor training.

  • Atmospheric testing must be conducted prior to entry. Results must be documented on the Assessment Form.
  • All existing and potential hazards must be identified and indicated on the Assessment Form.
  • All hazards must be effectively eliminated or controlled prior to entry and indicated on the Assessment Form.
  • Specialized equipment required must be indicated on the form.
  • What to do in the event of a confined space emergency must be discussed with the entrants and attendant prior to entry.
  • The departmental Entry Supervisor must determine and document the appropriate entry procedure on the Assessment Form by checking one of the boxes and signing the bottom of the form approving entry. Entry will either be: 
    • Non-Permit Entry (i.e. no existing or potential hazards present, or hazards have been eliminated or effectively controlled without entry into the space) - If all hazards can be controlled from outside of the space and there are no atmospheric hazards, entry may be conducted using the Confined Space Entry Procedure;
    • Alternate Procedure: If the only uncontrolled hazard is either an actual or potential atmospheric hazard, entry may be conducted under the Forced Air Ventilation Entry Procedure; or
    • Permit-Required Confined Space - If all hazards have not been effectively eliminated or controlled, the supervisor must consult with Environmental Health & Safety prior to using the Permit Entry Procedure.

During any confined space entry, all safety rules and procedures shall be followed.

  • Smoking in a confined space is prohibited.
  • Any use of chemicals in a confined space must be pre-approved by the Environmental Health & Safety coordinator, departmental safety coordinator, and the supervisor. 
  • Hot work, such as welding/cutting, conducted in a confined space must be in accordance with OSHA rules and regulations. 
  • Adequate and approved lighting (appropriate for the conditions) shall be provided.
  • Personal protective equipment (PPE) shall be provided to workers as necessary for safe entry. All PPE must be selected, used, and maintained in accordance with the Personal Protective Equipment Program.
  • All PPE must be approved by the Environmental Health & Safety coordinator, departmental safety coordinator, or the supervisor.
  • Electrical equipment (i.e.: power tools, extension cords) used in the confined space shall be appropriate for the hazard, such as explosion-proof or ground-fault circuit-interrupter (GFCI), and meet the requirements of the National Electric Code.
  • Any condition making it unsafe to remove an entrance cover must be eliminated before the cover is removed.
  • When the cover has been removed, the opening(s) shall be promptly guarded to prevent accidental falls into the opening and to prevent objects from falling into the opening. 
  • Appropriate vehicle and pedestrian barriers shall be used to protect workers.
  • Before entering the space, atmospheric testing must be performed with a calibrated, direct-reading instrument, for oxygen content, flammable gases and vapors, and potential toxic air contaminants.
  • No hazardous atmosphere is permitted within the space whenever any employee is inside the space.

Confined Space Rescue

Rescue team and patient

In the event that a confined space emergency occurs, regardless of the nature (entrant medical condition or a hazard with the space itself), the space reverts back to a permit-required confined space, and it must be reassessed prior to entry or re-entry.  

Begin implementation of the pre-defined rescue plan for the entry. Call 911 for emergency response, and indicate that the emergency involves a "confined space." Rescue plans include self-rescue, non-entry rescue, and entry rescue.

In the event that something goes wrong in a confined space, self-rescue would be the first response option. Self-rescue is where the entrant recognizes a problem early on, and exits the space on his/her own abilities. Problems could be inherent to the confined space, external events that adversely affect the space, or personal health/medical issues of an entrant. Regardless of the source, exiting the confined space on one's own at early warning signs is the best option. Examples include:

  • Responding to air monitoring alarms as soon as they sound by exiting the space immediately,
  • Recognizing early warning signs and symptoms of oxygen deficiency,  oxygen enrichment, carbon monoxide, and hydrogen sulfide exposure where continuous air monitoring is not required,
  • Being aware of personal health concerns that are deteriorating and need to be addressed. 

At the first sign of trouble, the entrants leave the space, get fresh air, and proper medical attention (if indicated). The space reverts back to permit-required until it has been reassessed and any hazards with the space have been effectively eliminated or controlled.

Where non-entry rescue protocols have been implemented for vertical entry spaces, the attendant shall immediately notify emergency services by calling 911. Once the call has been made, the attendant may begin rescue procedures. Under no circumstances may the attendant enter the confined space. Retrieval systems (e.g. tripod, winch, harness or wristlets, and lifeline) shall be used for entry when a vertical permit-required entry is made unless such equipment increases the overall risk of entry, or the equipment would not contribute to the rescue of the entrant.

Tripod for non-entry rescue

Where self-rescue or non-entry rescue means and methods are not possible:

  • The space must be reassessed prior to proceeding with entry rescue to verify that all hazard controls remain in place and are effective, and that no new hazards are now present.
  • All hazards must be eliminated or isolated prior to entry (and the space determined to be non-permit-required).
  • The event is determined to be an individual medical emergency (ex. heart attack, diabetic emergency, heat stress) by someone trained in first aid (or greater).
  • Only trained and authorized personnel may enter the non-permit-required space provided the Entry Supervisor approves it.
  • Extrication of the patient shall be coordinated with emergency responders.

If the space cannot be reclassified during the reassessment, rescue services shall be provided by local emergency medical and fire services. Virginia Tech personnel shall not enter a permit-required confined space for rescue purposes. Departmental efforts should be focused on cooperating with responding agencies to expedite rescue efforts, and/or providing support in the form of space accessment and expertise, available equipment, validation of controls, crowd control, etc.

Even with the best efforts to review and assess the potential hazards of a confined space entry, the potential for something to go wrong may still exist, such as unexpected events or individual medical conditions. Having a plan for emergencies prior to entry can save valuable time should an emergency occur. Confined space rescue pre-planning for departments that enter confined spaces on a regular basis is ongoing, and coordinated by Environmental Health & Safety with the department and emergency responders (police, fire, and rescue). Considerations include:

  • Having a means of calling 911 on-site.
  • Properly reporting the emergency to the 911 center so that emergency responders can arrive quickly and prepared.
    • Identify the emergency as involving a "confined space."
    • Provide the 911 address (street and building number). Give the nearest street and/or building if the space is not directly located at the address.
    • For remote spaces, such as high-voltage electrical vaults, provide the ELMH number of the vault.
  • Implement one of the rescue protocols above, as predetermined prior to entry.


Acceptable entry conditions: The conditions that must exist in a confined space before entering to ensure that employees can safely enter into, and safely work within, the space.

Attendant: A designated individual stationed outside of one or more permit spaces who assesses the status or authorized entrants, and who performs duties as specified by this program.

Barrier: A physical obstruction that blocks or limits access.

Blanking or blinding: The absolute closure of a pipe, line, or duct by the fastening of a solid plate (such as a spectacle blind or a skillet blind) that completely covers the bore and that is capable of withstanding the maximum pressure of the pipe, line, or duct with no leakage beyond the plate.

  • A blank is designed as a flat plate between two flanges, typically inside the flange bolt pattern. The blank must be sized for full design pressure (maximum non-shock presssure rating) of the line.
  • A blind is designed as a bolted flat plate, which can be used to terminate a pipe line. 

Competent Person: One who is capable of identifying existing and predictable hazards in the surroundings or working conditions which are unsanitary, hazardous, or dangerous to employees, and who has the authorization to take prompt corrective measures to eliminate them.

Confined space: Any space that is:

  1. Large enough and so configured that an employee can bodily enter it;
  2. Has limited or restricted means for entry or exit; and
  3. Is not designed for continuous employee occupancy.
  • Examples include, but are not limited to: bins, boilers, pits (e.g. elevator, escalator, pump, valve, etc.), manholes (e.g. sewer, storm drain, electrical, communication, or other utility), storage tanks (e.g. fuel, chemical, water, other liquid/solid/gas), incinerators, scrubbers, concrete pier columns, sewers, transformer vaults, heating/ventilation/air-conditioning (HVAC) ducts, storm drains, water mains, precast concrete and other pre-formed manhole units, drilled shafts, enclosed beams, vessels, digesters, lift stations, cesspools, silos, air receivers, sludge gates, air preheaters, step up transformers, turbines, chillers, bag houses, and/or mixers/reactors.

Control: The action taken to reduce the level of any hazard inside a confined space using engineering methods (ex. ventilation), and then using these methods to maintain the reduced hazard level. Personal protective equipment is not a control.

Controlling contractor: The employer that has overall responsibility for construction at the worksite. Note: If the controlling contractor owns or manages the property, then it is both a controlling employer and a host employer.

Double block and bleed: The closure of a line, duct, or pipe by closing and locking or tagging two in-line valves and by opening and locking or tagging a drain or vent valve in the line between the two closed valves.

Early-warning system: The method used to alert authorized entrand and attendants than an engulfment hazard may be developing. Ex. alarms activated by remote sensors, lookouts with equipment for immediately communicating with the entrants and attendants.

Emergency: Any occurrence or event inside or outside of the confined space that could endanger entrants, including any failure of power, hazard control, or monitoring equipment.

Engulfment: The surrounding and effective capture of a person by a liquid or finely divided (flowable) solid substance that can be aspirated to cause death by filling or plugging the respiratory system, or that can exert enough force on the body to cause death by stangulation, constriction, crushing, or suffocation.

Entrant (authorized): An employee authorized by the Entry Supervisor to enter a confined space. 

Entry: The action by which any part of a person passes through an operning into a permit-required confined space. Entry inlcudes ensuing work activities in that space and is considered to have occurred as soon as any part of the entrant's body breaks the plane of an opening into the space, whether or not such action is intentional or any work activities are actually performed in the space.

Entry employer: Any employer who decides that an employee it directs will enter a permit space. Note: an employer cannot avoid the duties of the standard merely by refusing to decide whether its employees will enter a permit space, and OSHA will consider the failure to so decide to be an implicit decision to allow employees to enter those space if they are working int he proximity of the space.

Entry permit: The written or printed document that is provided by the employer who designated the space a permit space to allow and control entry into a permit space and that contains the required information. At Virginia Tech, the Assessment Form serves as a permit if conditions are present that warrant the space being designated as permit-required.

Entry rescue: When a rescue service enters a permit space to rescue one or more employees.

Entry supervisor: The departmental person responsible for determining if acceptable entry conditions are present in a confined space where entry is planned, for authorizing and overseeing entry operations, and for terminating entry as required by this program.

Ground-fault circuit-interrupter: A device designed to disconnect an electric circuit when it seeks ground through a person or grounded object, thus preventing electric shock and fires.

Hazard: A physical hazard or hazardous atmosphere.

Hazardous atmosphere: An atmosphere presenting a potential for death, disablement, injury, or acute illness from one or more of the following causes:

  • A flammable gas, vapor, or mist in excess of 10 percent of its lower flammable limit (LFL),
  • An oxygen-deficient atmosphere containing less than 19.5 percent oxygen by volume, or an oxygen-enriched atmosphere containing more than 23.5 percent oxygen by volume,
  • Airborne combustible dust at a concentration that meets or exceeds its LFL (airborne combustible dust which obscures vision at five feet or less),
  • An atmospheric concentration of any substance for which a dose or a permissible exposure limit is published in Subpart G, Occupational Health and Environmental Control, or in subpart Z, Toxic and Hazardous Substances, which could result in employee exposure in excess of its dose or permissible exposure limit, and that could cause death, incapacitation, impairment of the ability to self-rescue, injury or acute illness,
    • Note: An atmospheric concentration of any substance that is not capable of causing death, incapacitation, impairment of the ability to self-rescue, injury, or acute illness due to its health effects is not covered by this definition. 
  • Any other atmospheric condition that is immediately dangerous to life or health (IDLH).
    • Note: For air contaminants for which OSHA has not determined a dose or permissible exposure limit (PEL), other sources of information, such as Safety Data Sheets (SDS), published information, and internal documents can provide guidance in establishing acceptable atmospheric conditions.

Host employer: The employer that owns or manages the property where the construction work (or confined space entry) is taking place. At Virginia Tech, the general contractor of capital projects is considered the property owner/manager. For non-capital projects, Virginia Tech remains the property owner/manager. Refer to Virginia Tech's Contractor Safety Program for more information regarding coordination of confined space entry involving contractors and subcontractors.

Hot work permit: The employer's written authorization to perform hotwork operations (e.g. welding, cutting, burning, or heating) capable of providing a source of ignition.

Immediately dangerous to life or health (IDLH): Any condition that poses an immediate or delayed threat to life, or that would cause irreversible adverse health effects or that would interfere with an individual's ability to escape unaided from a confined space. Note: Some materials, such as hydrogen fluoride gas and cadmium vapor, for example, may produce immediate transient effects that, even if severe, may pass without medical attention, but are followed by sudden, possibly fatal collapse 12-72 hours after exposure. The victim "feels normal" after recovery from transient effects until collapse. Such materials in hazardous quantities are considered to be "immediately" dangerous to life or health.

Inerting: The displacement of the atmosphere in a confined space by a noncombustible gas (such as nitrogen) to such an extent that the resulting atmosphere is noncombustible. Note: This procedure produces an IDLH oxygen-deficient atmosphere that can only be entered using self-contained breathing apparatus (SCBA) and following permit-required confined space entry procedures. 

Isolation: The process by which an energy source is removed from service and employees are completely protected against the release of energy and material into the space, and contact with a physical hazard, by such means as blanking or blinding; misaligning or removing sections of lines, pipes, or ducts; a double block and bleed system; lockout or tagout of all sources of energy; or blocking or disconnecting all mechanical linkages, or placement of barriers to eliminate the potential for employee contact with a physical hazard.

LEL/LFL: Lower Explosive/Flammable Limit; the minimum concentration of vapor-in-air or vapor-in-oxygen below which propagation of flame does not occur on contact with a source of ignition. Expressed in terms of percentage by volume of gas or vapor in the air. 

Limited or restricted means of egress (i.e. entry or exit): A condition that has the potential to impede an employee's movement into or out of a confined space. Ex. trip hazards, poor illumination, slippery floors, inclining surfaces, and ladders.

Line breaking: The intentional opening of a pipe, line, or duct that is or has been carrying flammable, corrosive, or toxic material, an inert gas, or any fluid at a volume, pressure, or temperature capable of causing injury.

Local exhaust ventilation: A system used during welding, cutting, or other similar operations in confined spaces as necessary to remove harmful gases, smoke, and fumes.

Lockout-tagout: Placing locks or tags on the energy isolating device (e.g. breaker boxes, control switches, valves, etc.) to prevent the unauthorized re-energization of the device or circuit while work is being performed by personnel. Tags shall indicate that the energy isolated device must not be operated until the tag is removed by the individual(s) that installed the tag.

Monitoring: The process used to identify and evaluate the hazards after an authorized entrant enters the space. It involves checking for changes periodically or continuously after the completion of the initial testing or evaluation of the space.

Non-entry rescue - When a rescue service, usually the attendant, retrieves employees in a permit space without entering the permit space.

Non-permit confined space: A confined space that does not meet the definition of a permit-required confined space.

Oxygen deficient atmosphere: An atmosphere containing less than 19.5% oxygen by volume. See signs and symptoms of low oxygen.

Oxygen enriched atmosphere: An atmosphere containing more than 23.5% oxygen by volume. 

PEL: Permissible Exposure Limit; the allowable air contaminant level established by the Occupational Safety and Health Administration (OSHA). 

Permit-Required Confined Space (PRCS): A confined space that after the evaluation is found to have one or more of the following characteristics:

  • Contains or has the potential to contain a hazardous atmosphere;
  • Contains a material that has the potential for engulfing an entrant;
  • 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
  • Contains any other recognized serious safety or health hazard.

Physical hazard: An existing or potential hazard that can cause death or serious physical damage. Ex. explosives, mechanical, electrical, hydraulic, and pneumatic energy, radiation, temperature extremes, engulfment, noise, inwardly converging surfaces, chemicals that can cause deather or serious physical damage through the skin or eye contact (rather than through inhalation), etc.

Qualified Person: One who by possession or a recognized degree, certificate, or professional standing, or who by extensive knowledge, training, and experience, has successfully demonstrated his/her ability to solve or resolve problems relating to the subject matter, the work, or the project.

Rescue team: Those persons whom the employer has designated prior to any permit-required confined space entry to perform rescues from confined spaces.

Retrieval system: The equipment used for non-entry rescue of persons from confined spaces, and includes retrieval lines, chest or full-body harness, and a lifting device or anchor. A retrieval line is primarily for use in vertical entry confined spaces, and must not be used in confined spaces consisting of horizontal tunnels or spaces where obstructions could increase the hazard to the entrant during emergency retrieval.

Serious physical damage: An impairment or illness in which a body part is made functionally useless, or is substantially reduced inefficiency. It may be permanent or temporary. Ex. loss of consciousness, disorientation, reduction in mental efficiency, etc. Such impairment would usually require treatment by a physician or other licensed healthcare provider.

Testing: The process by which the hazards that may confront entrants to a confined space are identified and evaluated. The tests that are to be performed in the permit space must be specified (ex. oxygen, LEL, carbon monoxide, and hydrogen sulfide).

UEL/UFL: Upper explosive/flammable limit; the maximum proportion of vapor or gas in the air above which flame propagation does not occur. Expressed in terms of percentage by volume of gas or vapor in the air. 

Ventilation: Controlling a hazardous atmosphere using continuous forced-air mechanical systems that meet the requirements of OSHA (1926.57).

Zero mechanical state: The mechanical potential energy of all portions of the machine or equipment is set so that the opening of the pipe(s), tube(s), hose(s), or actuation of any valve, lever, or button will not produce a movement which could cause injury.

Frequently Asked Questions

If entry/exit is restricted or limited, which it typically is, then an attic would be considered to be a confined space; however, they typically are not considered to be permit-required confined spaces because they usually have either natural or mechanical ventilation and other hazards typically are not present. The attic would need to be evaluated using the Assessment Form prior to entry.

Outside personnel must have approval from the Division of Campus Planning, Infrastructure, and Facilities prior to entering the steam tunnels to perform a specific task or provide a specific service.

  • Contractor's bidding on a project, architects and engineers designing for the project, and outside inspection/certification services in the steam tunnels must be escorted by trained Facilities personnel working on the project (typically renovations or capital project managers or project coordinators or mechanical utilities).
  • Once a contract has been awarded for the project, outside personnel entering the steam tunnels for the scope of the project must enter under their own Confined Space Program, which includes an assessment of the space including air monitoring and employee training. Virginia Tech personnel will enter under Virginia Tech's Confined Space Program and perform a separate assessment and air monitoring.
  • Contracted labor working under the direct supervision of Virginia Tech personnel must have proof of training by their company prior to being assigned work in a confined space. The supervisor in charge should make a copy of the training document and keep it on file.

Yes, provided that the means of entry/exit is limited or restricted.

Yes. Where the steam tunnels must be entered through a manhole or similar access, they are considered to be a confined space, and may be considered a permit-required confined space depending on hazards associated with a specific section of the tunnel, such as cross sections where there is a greater potential for a toxic atmosphere, extreme temperatures, or work being performed.

Yes. The type of "dust" that can result in an explosion is that from any material in its bulk form that will burn, such as coal, cotton, grain, sugar, etc. It does not include dust from soil, which will not burn in its bulk form.

Although there is no set parameter for excessive dust in a confined space, there is a rule of thumb that can be followed. When the concentration of dust in the confined space is such that vision is obscured at a distance of 5 feet, it is considered to be potentially explosive and should be controlled through ventilation, wet methods, etc.

In order for dust to explode, the right concentrations of dust and oxygen must be present, in addition to an ignition source, which could be electrical equipment, metal striking tools, illegal smoking, etc.

Is training mandatory? If so, when? Yes. Persons who work around, but not in, confined spaces must have this training.

Class length: 1 hour.

Available online: Yes.


When is refresher training required? Every 5 years.


Please see the online class schedule for more information.

Is training mandatory? If so, when? Yes. Persons who enter confined spaces and their supervisors must have this training.

Class length: 3 hours.

Available online: No.

When is refresher training required? Every 3 years.

Please see the online class schedule for more information.


Yes. Air monitoring must be performed to verify the absence of a hazardous atmosphere and that conditions are safe for entry. Oxygen, carbon monoxide, hydrogen sulfide and the LEL (Lower Explosive Limit) must be monitored. If there are additional potential contaminants, monitoring may be required for those as well.

First, air monitoring should be conducted from outside of the confined space. A pump may be necessary to draw air from the space. All levels of the confined space should be checked - the top, mid-section, and bottom. Gases can be lighter than air, heavier than air, or similar to air. Testing all levels of a space ensures that all gases are detected.

Continuous air monitoring is a best practice and should be used whenever possible. It is required where ventilation is the control method for a potentially hazardous atmosphere (i.e. initial air monitoring indicated conditions unacceptable for entry).

A large number of confined spaces have been identified at Virginia Tech including utility vaults, tunnels, silos, tanks, equipment, and crawl spaces. Only personnel trained and knowledgeable of related hazards may enter confined spaces.

Prior to entry, each space must be assessed by a trained supervisor and documented. Identified hazards must be eliminated, isolated, or controlled prior to entry.

The list includes, but is not limited to:

  • Carbon monoxide
  • Hydrogen cyanide
  • Hydrogen sulfide
  • Arsine
  • Chlorine
  • Ammonia
  • Oxides of nitrogen

In general, carbon monoxide is a colorless, odorless, tasteless gas that can result in asphyxiation by preventing oxygen transport in the blood. It is created from incomplete combustion from burning fuels or microbial decomposition or organic matter in sewers, silos, and fermentation tanks.

At 200 ppm exposure for a few hours, mild frontal headache may be experienced. At 400 ppm, headache and nausea can occur. At 800 ppm, headache, dizziness, and nausea may occur after 45 minutes of exposure and possible collapse and death in 2 hours. At 1600 ppm, headache, dizziness, nausea in 20 minutes, and possible collapse and death in 1 hour. At 3200 ppm, headache and dizziness in 5-10 minutes and unconsciousness and danger of death in 30 minutes. At 6400 ppm, headache and dizziness within 1-2 minutes and unconsciousness and danger of death in 10-15 minutes. An at 12800 ppm, immediate effects such as unconsciousness and danger of death in 1-3 minutes.

Continuous air monitoring is the best means of protection. Detecting early signs and symptoms of exposure and getting to fresh air can also prevent overexposure.

Hydrogen sulfide is a colorless gas with a rotten egg like odor. It can appear naturally or as a byproduct of decomposition. Hydrogen sulfide is considered a highly toxic gas because it reacts with enzymes in the blood stream and can inhibit cell respiration. Although hydrogen sulfide is easily detected by sense of smell, it is a desensitizer at 100 ppm after 2-5 minutes of exposure. Common signs and symptoms include:

  • At 100 ppm, coughing and eye irritation.
  • At 200-300 ppm, eye inflammation and respiratory tract irritation after 1 hour.
  • At 500-700 ppm, loss of consciousness, stopping or pausing of respiration, and death.
  • At 1000-2000 ppm, immediate unconsciousness and death within a few minutes.

Continuous air monitoring and ventilation are the best means of prevention.

Normal air contains approximately 20.8 percent oxygen by volume.  The minimum safe level for confined space entry is 19.5 percent.  As the oxygen level decreases, the following signs and symptoms may be experienced:

  • At 15 percent, impaired muscle coordination, increase heart rate, rapid fatigue, and intermittant respirations.
  • At 12 percent, judgment may become impaired and respirations continue to increase due to the lack of oxygen.
  • At 10 percent, lips may begin to turn blue, respirations increase, nausea, and inability to perform simple tasks.
  • At 8 percent, fainting and vomiting can occur.
  • At 6 percent, death can occur in about 8 minutes.
  • At 4 percent, likely coma in about 40 seconds, with possible recovery within 4 minutes.

Continuous air monitoring and ventilation is the best means of prevention. 

Silo gas is the common name for nitrogen dioxide. It is a yellowish-brown or reddish-brown gas that has a pungent, acrid odor. It can be found in diesel fuel when burned, or in silos containing corn silage.  Signs and symptoms include:

  • At 5-10 ppm, eye and throat irriatation.
  • At 20 ppm, eye irritation.
  • At 50 ppm and above, tightness in the chest, acute bronchitis, and death from prolonged exposure.

Continuous air monitoring with monitor that detects nitrogen dioxide and ventilation are the best means of prevention, in addition to avoiding exposure during the initial phases of corn silage fermentation, which can last up to 2 weeks after filling the silo.

A confined space is an area that meets all three of these criteria:

  1. Is large enough for the entire body to enter
  2. Has limited or restricted means of egress; and
  3. Is not designed for continuous human occupancy (i.e. does not have lighting, ventilation, adequate room to work, etc.).

According to OSHA, a permit-required confined space is a confined space that meets any of the following criteria:

  1. Contains, or has the potential to contain, a hazardous atmosphere;
  2. Contains a material the 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. Other recognized health or safety hazards.

IDLH means immediately dangerous to life and health. The hazard, such as a toxic gas, poses an immediate threat to health or life, would cause irreversible adverse health affects, or would interfere with your ability to escape a confined space unaided. Examples of gases which may pose an IDLH atmosphere include oxygen-displacing gases, such as argon, nitrogen, carbon dioxide, helium, or even steam. The IDLH level for carbon monoxide is 1200 ppm, for example.

Any person using a respirator, whether in a confined space or not, should be properly trained and fitted through Environmental Health & Safety. Contact 540-231-3600 for more information.

Asphyxiation can occur when a substance, such as carbon dioxide, interferes with the oxygenation of tissue. Suffocation can occur when the air supply to the body is blocked from entering the body. Unfortunately, the results can be the same - death.

An attendant is required whenever the space is considered permit-required. At Virginia Tech, a permit space is one where all hazards have not been eliminated, isolated, or controlled through ventilation. If a permit space is to be entered, the Entry Supervisor should contact Environmental Health & Safety to coordinate entry activities.

Many departments use a best practice of having an attendant where one is not required (i.e. space is not permit-required). The attendant should attend training for entrants/attendants/supervisors in order to recognize potential hazards and perform associated duties.

Contact our Program Coordinator Robin McCall-Miller by e-mail or at 540-231-2341.

Contact Information

Robin McCall-Miller, Occupational Safety Program Manager

Phone: 540-231-2341