Air Quality Control

Supplied-air respirators (SARs), such as SCBAs, must deliver air that is held to a high quality standard. SARs can use compressed or liquid oxygen, or compressed breathing air. Compressed and liquid oxygen must meet the United States Pharmacopoeia requirements for medical or breathing oxygen. Compressed breathing air must meet the following minimum standards:

• Oxygen content between 19.5 percent and 23.5 percent
• Hydrocarbon content of 5 milligrams per cubic meter or less
• Carbon monoxide content of 10 parts per million or less
• Carbon dioxide content of 1,000 parts per million or less
• No noticeable odor

Because humans cannot breathe oxygen alone, compressed or liquid oxygen may be used only in respirators that are designed for oxygen distribution. Compressed breathing air with an oxygen content of more than 23.5 percent must also only be used in respirators designed for oxygen distribution. Compressed oxygen should never be used in any SAR that previously used compressed air.

To learn more about Respiratory Protection visit our Cal/OSHA Respiratory Protection Online Training web page.