“When my employer said he wanted to send me on a training course so that I could work safely in confined spaces, I thought it was a bit unnecessary. Was he worried about me bumping my head or something? What an eye-opener! I never realized that there were so many dangers involved in working in a confined space, or that there had been so many terrible accidents related to confined-space work.”

One of the biggest dangers of working in a confined spaces is the lack of multiple escape routes should anything go wrong. For example, 5 workers died after a fire broke out in a confined space at a hydroelectric plant in Colorado. They were able to stay out of the flames, but they succumbed to oxygen deprivation as rescue workers struggled to gain access to the tunnel in which they had been working.

This accident also underlines the danger of fumes building up in confined spaces. In a 2014 accident at the Corona brewery, several workers died because of toxic air quality. The saddest thing about these deaths is that they could have been prevented if adequate risk assessments had been conducted and appropriate safety precautions had been taken.

What is a confined space?

OSHA defines a confined space as a space with limited entry and exit routes that has not been designed for extended human occupancy. Such spaces include pipelines, hoppers, vaults, silos, manholes, tanks and storage bins.

Permits are required for work in any space that has poor air quality, dangerous fumes, or that contains a material that can engulf a person (grain silos are a good example of this). If the space tapers down to a small space in which workers can be trapped or smothered, or contains exposed moving parts or live wires, or if a space is extremely hot, permits and special precautions are also required.

What are the risks?

  • Toxic air
  • Too little oxygen
  • Too much oxygen (ignition hazard)
  • Flammable or explosive atmosphere
  • Flowing liquids and solids
  • Falls
  • Exposed machinery or live wires
  • Heat

What precautions should be taken?

Employers need to take a lot of things into account before sending employees into a confined space. These include the following:

  • Air quality must be tested and an appropriate breathing apparatus must be supplied
  • Safety procedures applicable to the space should be determined in advance
  • Any chemicals to be used in a confined space must be assessed for possible health risks
  • Emergency rescue plans and procedures must be in place and be rehearsed
  • Appropriate PPE and tools should be supplied and employed
  • Workers entering confined spaces must have proper training
  • Time spent in confined spaces should be limited

If it as at all possible to devise a way in which maintenance can be carried out remotely, these methods should be applied.

From a worker perspective

  • Apply what you have learned in training
  • Remain alert for any hazards that have been identified
  • Use your PPE including respiratory protection and safety lines when applicable
  • Follow all safety precautions – no shortcuts
  • Know the emergency rescue procedure well and review before entering the confined area
  • Stay in touch with your outside backup crew
  • Monitor atmosphere during ‘hot work,’ such as welding
  • If at any time you begin to feel disorientated or experience physical symptoms, such as headaches, leave the space immediately


Ensure that you have qualified personnel to do the pre-entry risk assessment. OSHA supplies a pre-entry checklist for confined spaces that allows you to fill in your permit information and record factors such as the results of air-quality testing. It also allows you to record communication and rescue procedures that will be determined during your risk-assessment.

Work in confined spaces is extremely dangerous and should not be undertaken without thorough risk assessment and risk management planning. All personnel involved in confined-space work must be properly trained.