• Confined spaces are difficult to enter, exit, and move within, and they pose a serious risk of asphyxiation.

There are safety and health hazards involved in responding to incidents in confined spaces. The openings are usually small and are difficult to move through easily, which makes the transport of protective equipment a chore.

Simply put, a confined space is any space that meets three criteria:

• It’s large enough for a worker to enter,
• It has limited means of entry or exit, and
• It’s not designed for continuous occupancy.

Examples of confined spaces include tanks, vessels, silos, storage bins, hoppers, vaults, boilers, pits, sewers, and crawl spaces.

Confined space hazards

Because air may not move in or out of confined spaces freely due to the design, the atmosphere inside a confined space can be very different from the atmosphere outside. Deadly gases may be trapped inside, or there may not be enough oxygen to support life. Therefore, occasional worker entry for inspection, maintenance, repair, cleanup, or similar tasks is often difficult and dangerous due to chemical or physical hazards within the space.

In addition to oxygen deficiency and toxic air contaminants, confined spaces may contain combustible gases, electrical hazards, moving parts, and even snakes.

Permit spaces

With so many hazards, permits are often required just to perform work in a confined space. In fact, a confined space is considered a permit-required confined space (called a permit space) if it has:

• A hazardous atmosphere;
• The potential for engulfment or suffocation;
• An internal layout that might trap an entrant, such as by inwardly converging walls or a sloped floor; or
• Any other recognized serious hazard.

Please refer to the Confined spaces subject for further information.