Confined Spaces and Toxic Air: Ensuring Worker Safety in High-Risk Areas

Confined spaces—like tanks, manholes, silos, and pipelines—pose serious risks due to limited airflow, restricted entry/exit, and the potential buildup of toxic gases. In Canada, these environments have contributed to numerous workplace injuries and fatalities, often because the hazards weren’t properly recognized or managed. Understanding the risks and implementing effective controls is crucial for protecting workers in these high-risk spaces.

What Is a Confined Space?

Under Canadian regulations, a confined space is defined as an enclosed or partially enclosed area that:

  • Is not designed for continuous human occupancy,
  • Has limited means of entry or exit,
  • May contain hazardous atmospheric conditions or other safety risks.

Examples include tanks, sewers, crawl spaces, vats, and ductwork.

The Hidden Threat: Air Quality

confined space entrance on concrete ground Among the most dangerous—but often invisible—hazards in a confined space is toxic or oxygen-deficient air.

Common atmospheric hazards include:

  • Low oxygen levels (below 19.5%), which can lead to dizziness, unconsciousness, or death,
  • Oxygen enrichment (above 23%), increasing the risk of fire or explosion,
  • Toxic gases like hydrogen sulfide (H₂S), carbon monoxide (CO), and methane,
  • Flammable vapours or airborne particulates such as combustible dust.

According to data from the Canadian Centre for Occupational Health and Safety (CCOHS), atmospheric hazards are among the leading causes of confined space fatalities.

Real-World Example

A 2016 incident in British Columbia led to the deaths of two workers inside a confined space due to hydrogen sulfide exposure—a stark reminder of the consequences of inadequate air monitoring and safety procedures.

Regulatory Framework in Canada

Across Canada, confined space regulations vary slightly by province but are generally aligned with federal guidelines under Canada Occupational Health and Safety Regulations (COHSR), Part XI.

For example:

These regulations typically require:

  • Hazard assessments,
  • Entry permits,
  • Atmospheric testing,
  • Rescue procedures,
  • Worker training.

Steps to Ensure Safety in Confined Spaces

To prevent incidents, employers must establish a comprehensive confined space safety program. Key components include:

  1. Identify and Assess Confined Spaces

Start by conducting a hazard assessment to determine which spaces are confined and whether they pose atmospheric or physical risks.

  1. Air Monitoring

Before entry, test the air using a calibrated gas detector to check:

  • Oxygen concentration,
  • Flammable gases and vapours,
  • Specific toxic substances (e.g., H₂S, CO).

Continuous monitoring should be in place while workers are inside.

  1. Ventilation

Use mechanical ventilation (e.g., air movers or blowers) to eliminate or control hazardous atmospheres. This is especially important during tasks like welding, painting, or cleaning.

  1. Permit System

Most provinces require a written entry permit outlining:

  • Hazards present,
  • Protective measures in place,
  • Duration of entry,
  • Names of authorized entrants and attendants.
  1. Training and Communication

All workers involved in confined space entry must be trained in:

  • Hazard recognition,
  • Emergency response,
  • Proper use of PPE and monitoring equipment.

Communication between entrants and attendants is essential during the entire operation.

  1. Rescue Planning

Canadian regulations mandate a rescue plan for every confined space entry. This must include:

  • A designated, trained rescue team,
  • Appropriate rescue equipment (e.g., tripod and winch, SCBA),
  • Regular practice drills.

Delayed or poorly executed rescue attempts have resulted in multiple fatalities in past incidents.

The Role of Industrial Hygienists

consultant shaking site manager hand Certified industrial hygienists play a critical role in confined space safety. They:

  • Perform detailed hazard assessments,
  • Recommend appropriate air monitoring strategies,
  • Advise on ventilation and PPE,
  • Ensure regulatory compliance.

Partnering with a qualified professional helps reduce risk and protect workers’ lives.

Final Thoughts

Confined spaces may look harmless, but they can be lethal without proper controls. In Canada, toxic air remains a significant hazard in these environments. By adhering to provincial OHS regulations, using reliable air monitoring, and ensuring workers are trained and prepared, employers can drastically reduce the risk of injury or death.

Leave a Reply

Reach out to our Team Today!

    How Can We Help You?

    Contact us at JADA Solutions (HSE) Inc. to speak with one of our professionals!

    Newsletter