A confined space is defined as an enclosure that is difficult to get out of and has limited or no ventilation. Examples of confined spaces include: storage tanks, silos, boilers, sewers, tank cars, and crawl spaces.
OSHA
uses the term "permit-required confined space" (permit space) to
describe a confined space that has one or more of the following
characteristics: contains or has the potential to contain a hazardous
atmosphere; contains a material that has the potential to engulf an entrant;
has walls that converge inward or floors that slope downward and taper into a
smaller area which could trap or asphyxiate an entrant; or contains any other
recognized safety or health hazard, such as unguarded machinery or exposed live
wires.
