What are hazards in a confined space?

A confined space are areas in the workplace large enough for a worker to enter but not designed for continuous occupancy and has limited or restricted means for entry and exits. Common on construction sites, some examples of confined spaces include pipelines, tunnels, manholes, ductwork.

Some of the most common hazards of working in a confined space are:

  • No Ventilation: Without proper ventilation in a confined space, gases will begin to build up quickly. Even otherwise harmless gases can become deadly in a small space.
  • Instability: Underground or in storage areas can lead to falling objects or even a collapse of the confined space.
  • Lack of Oxygen: Limited available oxygen can cause workers to become lightheaded, leading to injuries or even death.
  • Traps: Because confined spaces have limited or restricted entries and exits, a blockage can trap employees inside.
  • Electrical Hazards: Many workers will enter a confined space to perform maintenance or work on electrical equipment.
  • Fires or Explosions: Confined spaces can fill with smoke quickly and explosions can cause the area to become unstable.
  • Smothering: Employees working with grain (like in silos), sand, rocks, or similar material are at risk to become engulfed quickly, smothering people.

Confined spaces should be adequately marked with safety signs and potential exits must be clearly identified. Before entering a confined space, employees should be equipped with the proper personal protective equipment (PPE).

OSHA requires employees entering hazardous to have a permit under 29 CFR 1910.146. Permit-required confined spaces have known hazards or potentially hazardous atmospheres. Entry permits guides both supervisors and employees through an evaluation of the confined space to be entered. All employees permitted or not, who work in or around confined areas should also be required to go through a formal training program provided by their employer.


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