What is a confined space?
Thousands of workers are exposed to possible death or injury each year in what are referred to as "confined spaces." The OSHA confined space standard defines a confined space as a space that is large enough for an employee to enter, has restricted means of entry or exit, and is not designed for continuous employee occupancy.

Where are the Regulations?
Specific regulations governing entry to confined spaces have been finalized recently by the Occupational Safety and Health Administration. These regulations are in the code of Federal Regulations, CFR Title 29, part 1910.146.

Examples of confined spaces include ship compartments, missile fuel tanks, vats, silos, sewers, tunnels and vaults. Although these environments are often dangerous, you might have to work in them to inspect equipment, hardware or structural elements, to clean, repair, or maintain them.

Confined Space Hazards
What makes a confined space hazardous? Dangerous vapors and gases can accumulate in these spaces. Fires, explosions and physical hazards can also injure or kill an unprotected worker. Let's look further at some of the dangers you might face in a confined space.

Physical Hazards
Physical hazards may result from mechanical equipment or moving parts like agitators, blenders and stirrers. Dangers may also be present from gases, liquids or fluids entering the space from connecting pipes. Before entering a confined space, all mechanical equipment must be locked out/tagged out. All lines containing hazardous fluids such as steam gases or coolants should also be shut off. Other physical hazards include heat and sound. Temperatures can build up quickly in a confined space and cause exhaustion or dizziness. Sounds may reverberate and make it hard to hear important directions or warnings.

Oxygen Deficiency
Most confined space accidents are related to atmospheric conditions inside the space or to the failure to continuously monitor hazards, which are present. In general, the primary hazard associated with confined spaces is oxygen deficiency. Normal air contains 20.8 percent oxygen by volume and the minimum safe level as indicated by OSHA is 19.5 percent. At 16 percent you will feel disoriented and between 8 and 12 percent you will generally become unconscious. Oxygen is reduced in a space either by displacement or consumption. Other gases such as argon, nitrogen or methane displace oxygen. Consumption may be caused by chemical reactions such as rusting, rotting, fermentation, or burning of flammable substances.


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