Skip Navigation
Safety guides and audits to make your job as a safety professional easier

Non-Atmospheric Hazards

Hazardous atmospheres are not the only hazards within confined spaces.

Physical Hazards in Confined Spaces

Hazardous atmospheres are not the only hazards within confined spaces. As we'll see, there are many actual and potential non-atmospheric hazards within confined spaces and we need to be aware of them to make sure they are eliminated.

Mechanical Hazards

If activation of electrical or mechanical equipment would cause injury, each piece of equipment should be manually isolated to prevent inadvertent activation before workers enter or while they work in a confined space.

The interplay of hazards associated with a confined space, such as the potential of flammable vapors or gases being present, and the build-up of static charge due to mechanical cleaning, such as abrasive blasting, all influence the precautions which must be taken.

  • To prevent vapor leaks, flashbacks, and other hazards, workers should completely isolate the space.
  • To completely isolate a confined space, the closing of valves is not sufficient.
  • All pipes must be physically disconnected or isolation blanks bolted in place.
  • The pipes blanked or disconnected should be inspected and tested for leakage to check the effectiveness of the procedure.
  • Other areas of concern are steam valves, pressure lines, and chemical transfer pipes.

A less apparent hazard is the space referred to as a void, such as double walled vessels, which must be given special consideration in blanking off and inerting. Other special precautions must be taken in cases where flammable liquids or vapors may re-contaminate the confined space.

1. What should be done if the activation of electrical or mechanical equipment could cause injury while working in a confined space?

a. Stay clear of the equipment
b. Isolate each piece of equipment
c. Post warning signs
d. Do not permit entry

Next Section

Skin Contact Hazards

Toxic solvents, chemical removers, and flammable and combustible liquids can harm employees eyes and skin. Workers should understand the hazards associated with the materials used and contained in the space. This includes training in accordance with the Hazard Communication Standard. Hazards may include:

  • Organ damage by absorption through the skin or eye.
  • Eye or skin irritation.
  • Defatting of skin.

Requirements and Example Solutions:

  • Use appropriate personal protective equipment (PPE).
  • Clean up spills or other releases of flammable, combustible, toxic, corrosive and irritant materials as work progresses.
  • Ensure that washing facilities are available.

Access and Egress

When working in confined or enclosed spaces, egress may be blocked by:

  • Improperly located equipment.
  • Temporary ventilation ducts and hoses running through the entrance.
  • "Interference" such as piping, ventilation ducts, and electrical wiring.

Requirements and Example Solutions:

  • When employees work in confined or enclosed spaces with limited access, the access must not be blocked or impeded by ventilation ducts, hoses, or other equipment.
  • More than one means of access must be provided where practical.
  • Additional openings should be considered for ducts, hoses, and other equipment.

2. When employees work in confined or enclosed spaces with limited access, _____.

a. the access must not be blocked or impeded by equipment
b. the access must be wide enough for two entrants
c. at least 2 access points must be provided
d. ventilation must be removed during operations

Next Section

Slip and Trip Hazards

Workers can be exposed to slippery working surfaces and tripping hazards.

Workers can be exposed to slippery working surfaces and tripping hazards. This places workers at risk of:

  • Slipping off oily and greasy ladders.
  • Slipping and falling on oily surfaces.
  • Tripping over equipment, hoses, and structures.

Requirements and Example Solutions:

  • All spills should be cleaned up immediately.
  • Visual inspection should be conducted.
  • Adequate illumination should be provided.
  • Housekeeping should be maintained.

Fall Hazards

Fall hazards are a leading cause of workplace fatalities. Employees are often required to work in dangerous environments that may include fall hazards. Accidents involving elevation equipment such as ladders, scaffolds, and aerial lifts are often serious, even fatal.

Employees useproper personal fall protection equipment.
Here are just a few scenarios where falls could occur:

  • Deck Openings and Edges
  • Falls from roof edges
  • Falls from floor openings
  • Falls into open holes
  • Falls from ladders
  • Falls from scaffolds

Personal Fall Protection System

If fall hazards in confined spaces are identified through a hazard assessment, employees must be protected from falls by the use of personal fall protection equipment, including body harnesses and lifelines.

Guardrails may be used to protect workers along floor openings or edges, in lieu of personal fall protection.

3. If fall hazards in confined spaces are identified through a hazard assessment, employees must be protected from falls by _____.

a. hole covers
b. personal fall arrest protection, including body harnesses and lifelines
c. personal fall protection and guardrails
d. warning signs and cones

Next Section

Work Environment Temperature Related Hazards

A thermal hazard is a dangerous condition caused by excessive heat or cold or a hot surface. A confined space entry permit must address any hazards from heat or cold within confined spaces.

Four factors influence the interchange of heat between people and their environment. They are:

  1. air temperature,
  2. air velocity,
  3. moisture contained in the air, and
  4. radiant heat.

Because of the nature and design of most confined spaces, moisture content and radiant heat are difficult to control. A combination of PPE use, heat-producing equipment, work activity, and environmental conditions can cause temperature-related illnesses. As the body temperature rises progressively, workers will continue to function until the body temperature reaches approximately 102oF. Heat-related illnesses include: heat stress, cramps, stroke, and dehydration.

The following precautions for heat-related illnesses are recommended:

  • plenty of fluids,
  • frequent breaks,
  • ice vest,
  • shaded or cooled break areas,
  • ventilation, and
  • awareness training.

In a cold environment, certain physiological mechanisms come into play, which tend to limit heat loss and increase heat production. The most severe strain in cold conditions is chilling of the extremities so that activity is restricted. Special precautions must be taken in cold environments to prevent frostbite, trench foot, and general hypothermia.Cold-related illnesses include: hypothermia and frostbite.

The following precautions for cold-related illnesses are recommended:

  • appropriate insulated PPE,
  • warming areas for breaks, and
  • awareness training.

4. Employees engaged in continuous heavy work in a confined space while wearing body suits and respirators susceptible to _____.

a. impaired hearing
b. strains and sprains
c. hypothermia
d. heat stress

Next Section

Communication between the worker inside and the standby person outside is of utmost importance.

Communication Problems

Communication between the worker inside and the standby person outside is of utmost importance. If the worker should suddenly feel distressed and not be able to summon help, an injury could become a fatality. Frequently, the body positions that are assumed in a confined space make it difficult for the standby person to detect an unconscious worker. When visual monitoring of the worker is not possible because of the design of the confined space or location of the entry hatch, a voice or alarm-activated explosion proof type of communication system will be necessary.

Excessive Noise Hazards

Noise problems are usually intensified in confined spaces because the interior tends to cause sound to reverberate and thus expose the worker to higher sound levels than those found in an open environment. This intensified noise increases the risk of hearing damage to workers which could result in temporary or permanent loss of hearing. Noise in a confined space which may not be intense enough to cause hearing damage may still disrupt verbal communication with the emergency standby person on the exterior of the confined space. If the workers inside are not able to hear commands or danger signals due to excessive noise, the probability of severe accidents can increase.

If noise levels are high, a hearing conservation program may need to be implemented. Use of tools and equipment may produce high noise levels, which could lead to permanent hearing loss, and often necessitates a hearing conservation program. Some examples of excessively loud operations include:

  • Use of high-pressure water and steam guns
  • Abrasive Blasting
  • Needle Gunning
  • Scaling
  • Grinding

Requirements and Example Solutions:

  • Hearing protection
  • Hearing conservation program

5. Grinding, abrasive blasting, and using high-pressure hoses in confined spaces may result in _____.

a. disorientation
b. cold stress
c. hearing impairment
d. segmental vibration injury

Next Section

High-Pressure Hazards

The use of high-pressure equipment may expose operators and bystanders to the following hazards:

  • Contact with high-pressure steam, water, grit, or air streams from cleaning equipment.
  • Contact with uncontrolled high-pressure hoses.

Injuries associated with these hazards include:

  • Loss of body parts (for example, fingers, or hands)
  • Lacerations
  • Burns
  • Loss of sight

Requirements and Example Solutions:

  • Use appropriate PPE.
  • Control access to the area.
  • Inspect hoses and connections prior to use.
  • Use pressure equipment according to the manufacturer's recommendations.
  • Warning: Do not use oxygen for cleaning (blow-off), operation of air tools, or ventilation

6. What is the requirement for the use of oxygen when cleaning (blowing-off), operating air tools, or using ventilation?

a. Keep oxygen pressure below 20 mmHg
b. Do not use oxygen
c. Inspect daily
d. Pressure must be less than 80% oxygen

Next Section

Electrical Hazards

Potential Hazards:

All workers who work with electrical equipment in wet or damp locations have an increased risk of getting shocked or electrocuted due to:

  • Faulty electrical connection in power tools.
  • Open lighting parts.
  • Broken insulation on power cables and cords.

Requirements and Example Solutions:

  • Portable electrical tools must be grounded or double insulated.
  • Temporary lighting must be grounded.
  • All electrical tools or equipment should undergo a visual inspection prior to use.
  • All portable electric hand tools and temporary lighting systems should utilize Ground Fault Circuit Interrupters (GFCI).
  • Electrical tools and equipment should correspond with the requirements of the job.
  • Electrical equipment and tools should be used with proper circuit protection for the voltage and amperage used.
  • Only qualified electricians should attempt to repair electrical tools and equipment.

A Ground Assurance Program should be in place for all electrical tools and equipment used including:

  • Records of tools inspected and repaired.
  • Records of electrical boxes inspected and repaired.
  • Records of electrical extension cords inspected and repaired.
  • Recall of records of the above.
  • The requirements of the Ground Assurance Program should be performed on a regular basis.

7. All portable electric hand tools and temporary lighting systems should use _____.

a. class II insulated equipment
b. in-line fuses
c. two-way switches
d. Ground Fault Circuit Interrupters (GFCI)

Next Section


Whole body vibration may affect multiple body parts and organs depending upon the vibration characteristics. Segmental vibration, unlike whole body vibration, appears to be more localized in creating injury to the fingers and hands of workers using tools, such as pneumatic hammers, rotary grinders or other hand tools which cause vibration.

Impact Hazards

Workers may be exposed to impact hazards from:

  • Sparks
  • Metal particles
  • Grinding debris
  • Paint debris

Injuries may include:

  • Particles becoming imbedded in the skin
  • Eye damage
  • Skin burns
  • Skin trauma

Requirements and Example Solutions:

  • Use PPE properly.
  • Use powered equipment such as portable grinders with guards and according to the manufacturer's recommendations.

It's important to understand that moving equipment or parts and energized or pressurized systems can be extremely dangerous in confined spaces. Examples include shafts, couplings, gears, belts, conveyors, mixers, rotors, and compressing devices. If you get caught in moving equipment, you will most likely suffer a fatal injury. The equipment will not stop rotating or moving.

8. What is the most likely outcome if you get caught on a rotating shaft while working in a confined space?

a. A near-miss incident
b. A fatality
c. A serious injury
d. Property damage

Next Section

Entrapment Hazards

Entrapment Hazards
Click to Enlarge

Entrapment hazards in confined spaces include inwardly converging walls or floors that slope downward and taper to a smaller cross-section (such as air plenums).


Engulfment refers to the surrounding or burial of the worker in a liquid or loose, finely divided solid material, such as sand or grain. Such materials can suffocate a worker. Examples include:

  • Accidental dumping of a product on a worker.
  • A worker walking on unstable material such as settled grain. Such materials could conceal a void underneath that gives way under the weight of the worker, resulting in engulfment.

Other Physical Hazards

Some physical hazards cannot be eliminated because of the nature of the confined space or the work to be performed. These hazards include such items as scaffolding, surface residues, and structural hazards.

  • Scaffolding in confined spaces has contributed to many accidents caused by workers, materials falling, improper use of guard rails, and lack of maintenance to insure worker safety. The choice of material used for scaffolding depends upon the type of work to be performed, the calculated weight to be supported, the surface on which the scaffolding is placed, and the substance previously stored in the confined space.
  • Surface residues in confined spaces can increase the already hazardous conditions of electrical shock, reaction of incompatible materials, liberation of toxic substances, and bodily injury due to slips and falls. Without protective clothing, additional hazards to health may arise due to surface residues.
  • Structural hazards within a confined space such as baffles in horizontal tanks, trays in vertical towers, bends in tunnels, overhead structural members, or scaffolding installed for maintenance increase the likelihood of being injured.

9. Walking on unstable material such as grain in a confined space can result in a fatality by _____.

a. being unable to exit
b. a fall to below
c. entrapment
d. engulfment

Check your Work

Read the material in each section to find the correct answer to each quiz question. After answering all the questions, click on the "Check Quiz Answers" button to grade your quiz and see your score. You will receive a message if you forgot to answer one of the questions. After clicking the button, the questions you missed will be listed below. You can correct any missed questions and check your answers again.


Grain Bin Safety

Next Module

OSHAcademy Ultimate Guide Banner Ad