Confined spaces can be dangerous due to limited entry/exit points, potential for hazardous atmospheres, and other safety risks. It is critical to follow safety procedures to mitigate these risks.

A confined space is defined as having limited openings for entry or exit, is large enough for entering and working, and is not designed for continuous worker occupancy. These spaces may include underground vaults, tanks, storage bins, manholes, pits, silos, underground utility vaults, and pipelines. [7]

The following procedures should be followed when working in a confined space:

• Hazard Assessment: Before entering a confined space, a trained and experienced person should identify and evaluate all existing and potential hazards within the confined space, including activities both inside and outside the space.
• Entry Permit System: Use an entry permit system to document the completion of a hazard and risk assessment for each confined space entry. The permit should include the duration of validity, authorized workers, attendants, supervisors, location, and description of the confined space.
• Air Quality Testing: The air within the confined space should be tested from outside the space before entry. Testing should check for oxygen content, hazardous atmospheres (toxic gases, flammable atmospheres), and proper ventilation equipment operation. Continuous monitoring should be considered where atmospheric conditions may change.
• Ventilation: Use mechanical ventilation (e.g., blowers, fans) to maintain air quality, as natural ventilation is usually insufficient. Ensure a warning system is in place to notify workers of ventilation equipment failure.
• Emergency Rescue Plan: A detailed emergency response plan should be included in the confined space hazard assessment and control program. Rescue personnel qualified in confined space rescue procedures should be available immediately nearby.
• Continuous Monitoring: The confined space should be continuously monitored to determine whether the atmosphere has changed due to the work being performed.

[5] [3] [4] [6] [1] [2] In an emergency, rescue procedures should begin immediately if a worker does not leave or is unable to leave the confined space. Rescue personnel should be familiar with the structural design of the confined space. [1] [1]

NIOSH recommends managers, supervisors, and workers be made familiar with recognition, testing, evaluation, and monitoring and rescue. [2]

Worker training is essential to recognize confined spaces and their hazards. Training should emphasize the potential for death if proper precautions are not taken. [2]