Construction of subway tunnel as confined space

Confined Space Safety

DF SafetyWorkplace Safety

Some work environments are more dangerous than others. One such example is working in confined spaces, which can be more hazardous than working in a regular workspace for many reasons. According to the Canadian Centre for Occupational Health and Safety (CCOHS), 60% of fatalities have been among would-be rescuers.  

What is a confined space? 

A confined space can be described as a space that is fully or partially enclosed. The CCOHS outlines a confined space as the following:  

  • Is not designed for continuous human occupancy. 
  • Has limited or restricted entrance or exit, complicates first aid, rescue, evacuation, or other emergency response activities. 
  • Represents a risk for health and safety of those entering due to its design, construction, location or atmosphere, the materials or substances in it, work activities conducted in it, or the mechanical, process and safety hazards present. 

These spaces may be below or above ground and aren’t necessarily small. Some examples include: 

  • Silos 
  • Vats 
  • Hoppers  
  • Utility vaults 
  • Tanks 
  • Water supply towers 
  • Sewers 
  • Pipes 
  • Access shafts 
  • Truck or rail tank cars 
  • Aircraft wings 
  • Boilers 
  • Manholes 
  • Pump stations 
  • Digesters 
  • Manure pits 
  • Storage bins 
  • Ditches, wells, trenches 
  • Barges, shipping containers, fish holds 

Safety rules to follow 

To keep workers safe, proper procedures must be in place, and followed accordingly. 

Risk assessment 

It is key to identify all the confined spaces in the workplace. To do this, a risk assessment should be done to evaluate potential dangers that can happen within these spaces. Some hazards may include toxic atmospheres, lack of oxygen, flammable gases, engulfment hazards, or mechanical risks. 

Each time a worker must enter a confined space, a confined space hazard assessment and control program must be followed.  

Confined space entry permit  

The CCOHS describes an entry permit as “an administrative tool used to document the completion of a hazard and risk assessment for each confined space entry.” Furthermore, someone who is fully trained and experienced in confined space work should complete this permit.

Some jurisdictions require a permit for all confined space entries, and one is needed when the hazard and risk assessment has determined risks including: 

  • atmospheric monitoring 
  • isolation 
  • lockout 
  • ventilation 
  • safeguarding devices 
  • respiratory protection 

Proper Training 

All workers who will be involved in confined space work should be properly trained. This includes understanding the hazards associated with the area, entry procedures, emergency response, and the appropriate use of personal protective equipment (PPE).


When working in a confined space, everyone should be aware and remain alert for any changes in the conditions within the space. One other worker (at least) should be posted outside of the area to continuously monitor the workers inside of the confined space. If danger or alarm from monitoring equipment is set off, workers need to immediately exit the space. 

Emergency Procedures 

It is key to have a clear emergency response plan when working in confined spaces. This will be detailed in the confined space hazard assessment and control program. If, for any reason, a worker is not able to exit the area, rescue procedures should happen immediately. Those who are trained in confined spaces rescue should always be available to help when needed. 

In Canada, all jurisdictions have regulations regarding confined space entry. Your workplace should have a hazard assessment and control program to ensure the safety of your workers. If you have questions about these regulations, please contact our team today.