Many workplaces contain spaces that are considered confined because their configurations impair the activities of any employees who must work in or exit them. An example of this is workers on process vessels, who are required to squeeze in and out through narrow openings, and carry out their work in a narrow or contorted position. These spaces are defined by OSHA as a confined space.

In confined spaces, workers often have an increased risk of exposure to chemical hazards. In some cases, confinement itself poses entrapment hazards. Confined space work can also keep employees closer to such hazards as asphyxiating atmospheres or the moving parts of machinery.

Spaces that both meet the definition of confined space and pose health or safety hazards are termed by OSHA permit required confined spaces.

The first step in preventing confined space injury is to recognize that an environment is a confined space. Since death in confined spaces often occurs because the atmosphere is oxygen-deficient or toxic, confined spaces should be tested prior to entry and continually monitored.

The URS SMS 010 Confined Space Entry provides additional information related to confined spaces. When entering a permit required confined space, this must be completed.