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wall mounted permit center

Safety Emporium carries signage and other items to help comply with OSHA confined space entry requirements.


Air is the mixture of gases that surrounds the Earth. The composition of the earth's atmosphere varies with altitude, but at sea level contains approximately 78% nitrogen and 21% oxygen by volume.

An oxygen-deficient atmosphere contains less than 19.5% oxygen by volume.

An oxygen-enriched atmosphere contains more than 23.5% oxygen by volume.

An atmosphere that is immediately dangerous to life or health (IDLH) poses an immediate threat to life, would cause, irreversible adverse health effects, or would impair an individual's ability to escape from a dangerous atmosphere.

Additional Info

The amount of water vapor in air tends to vary depending on the temperature and atmospheric pressure. Dry air at standard atmospheric pressure has the following composition:

Percent by Volume
Carbon DioxideCO20.033

Standard atmospheric pressure is defined as one atmosphere = 14.7 pounds per square inch (psi) = 760 torr. A list of pressure units and an on-line conversion calculator is available on this site.

Cylinders of compressed air are often used in industrial settings and laboratories. Be certain you are familiar with cylinder and compressed gas safety, including the proper use of gas regulators.

Oxygen-enriched atmospheres present exceptionally dangerous fire hazards (see link below). Oxygen-deficient atmospheres may result in unconsciousness, coma or death (see link below).

SDS Relevance

confined space entry wall poster

Safety Emporium carries signage and other items to help comply with OSHA confined space entry requirements.

Further Reading

See also: Asphyxiant, pressure units, ventilation.

Additional definitions from Google and OneLook.

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