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Confined spaces

Confined spaces in the workplace pose a significant risk of injury and death. Hazards in confined spaces can result in fire, explosion, unconsciousness, asphyxiation, or drowning. Confined space incidents can happen suddenly, often without any warning that something is wrong. Employers must take the necessary steps to ensure worker safety around confined spaces.

What is a confined space?

A confined space is an enclosed or partially enclosed area that is big enough for a worker to enter. The space may be enclosed on all sides (for example, a bin or tank), or as few as two sides (for example, an enclosed conveyor). Confined spaces are not designed for someone to work in regularly. They are places where entry may be needed from time to time for inspection, cleaning, maintenance, or repair.

You can recognize a confined space because it will not have things you would normally find in a workspace designed for occupancy, such as:

  • Permanent utilities (for example, ventilation systems, lighting, plumbing services)
  • Wall coverings and furniture
  • Easy access (for example, large doorways, stairways)

Common confined spaces include:

  • Bins
  • Bunkers
  • Conveyors
  • Crawl spaces or cellars
  • Large pipelines
  • Manure storage tanks, ponds, and pits
  • Mobile equipment
  • Pump or lift stations
  • Ship holds
  • Silos
  • Sumps
  • Tanks
  • Tunnels
  • Valve boxes (below ground)
  • Vats
  • Water cisterns and tanks
  • Wells

The risks

Incidents in confined spaces are not common, but when they do occur the consequences can be devastating. Confined space incidents can happen suddenly, often without any warning that something is wrong. Incidents involving atmospheric hazards (for example, toxic gases or a lack of oxygen) in confined spaces often cause serious injury or death to more than one person.

Typically, confined space incidents happen when:

  • A confined space is being prepared for entry
  • Workers or others are entering a confined space
  • Work is happening in a confined space

How to reduce the risks

There are important steps both employers and workers must take to reduce the risk associated with confined spaces.


As an employer, you are responsible ensuring the health and safety of your workers. This involves identifying confined space hazards in your workplace and taking the necessary steps to protect workers. Learn more about the five steps to managing confined space hazards in the workplace.

Hazards in confined spaces may not be obvious, so a qualified person — someone who has proper training and experience — must look carefully at every confined space in a workplace to identify possible hazards.


As a worker, there are three steps you can take to protect yourself and others from confined space hazards. Learn more about the three steps to working safely around confined spaces.