By definition, a confined space:

• Is large enough for an employee to enter fully and perform assigned work;
• Is not designed for continuous occupancy by the employee; and
• Has a limited or restricted means of entry or exit.

These spaces may include underground vaults, tanks, storage bins, pits and diked areas, vessels, silos and other similar areas.

By definition, a permit-required confined space has one or more of these characteristics:

• Contains or has the potential to contain a hazardous atmosphere;
• Contains a material with the potential to engulf someone who enters the space;
• Has an internal configuration that might cause an entrant to be trapped or asphyxiated by inwardly converging walls or by a floor that slopes downward and tapers to a smaller cross section; and/or
• Contains any other recognized serious safety or health hazards.

Furthermore the National Institute for Occupational Safety and Health (NIOSH) states that since the inception of the FACE program in 1982, 171 fatal incidents involving confined space entry and rescue efforts have been investigated by NIOSH and State investigators, and injuries and fatalities related to “confined space” labor has reached an average of 92 per year.

The importance of seeking trained and competent professionals for Confined Spaces services cannot be overstated

U.S. Department of Labor Occupational Safety and Health Administration
OSHA 3138-01R
2004

CDC website