Oxygen deficient environment (per OSHA)

• A. 19.5%
• B. 20.9%
• C. 18.0%
• D. 16.5%

Answer: (A)

Oxygen-deficient atmospheres are defined by OSHA as having less than nineteen point five percent oxygen by volume. Normal ambient air contains about twenty point nine percent O2, so it is not considered deficient. The regulatory threshold for labeling an environment as oxygen-deficient is nineteen point five percent; when O2 falls to this level or lower, monitoring and protective measures are required. Levels like eighteen percent or sixteen point five percent are also deficient, but the standard cut-off to designate an oxygen-deficient environment is nineteen point five percent.