United States Breathing Air Standards – A Complete Guide

Whether you are getting started working as a contractor, construction worker, or taking over a new role in safety you may come across references that list requirements for breathing air. For example, sandblast hood respirators when fed by a compressor are required to have atleast air of Grade D quality. This standard can be confusing at first but through this article, we will cover breathing air standards, what breathing air standards are, and important things to know when trying to meet breathing air standards.

Where Breathing Air Standards Come from

Breathing air standards were developed by ANSI and specifically the Compressed Gas Association of ANSI. These standards were then adopted by OSHA and enforced under the respiratory standard 29 CFR 1910.134.  The OSHA standard draws from the Gas Association Commodity Specification for air G-7-1989.

What are the Requirements for Grade D Air

To meet the Grade D breathing air standard the compressed air being supplied must consist of the following:

• Oxygen content of 19.5-23.5%
• Hydrocarbon (condensed oil
• ) content of 5 milligrams per cubic meter of air or less
• Carbon monoxide (CO) content of 10 ppm or less
• Carbon dioxide content of 1,000 ppm or less
• No noticeable odor
• The employer shall ensure that compressed oxygen is not used in atmosphere-supplying respirators that have previously used compressed air
• Water Content: High pressure cylinder air must have a dew point of at least -50o F (-45.6o C) at 1 atmosphere (14.7psi). Low pressure breathing air must have a dew point of at least 10o F (5.56o C) below the ambient temperature at 1 atmosphere (14.7 psi)

What about Grade E Breathing Air Requirements?

Grade E breathing air requirements are similar to Grade D but have a few differences. Grade E Breathing air requirements are also specified in standard G-7 1997 of the Compressed Gas Association.  It is similar to Grade D air but consists of the following differences. It applies to compressed air stored in air cylinders for breathing and differs in requirements as follows:

• Oxygen content – 20 – 22%
• Total Volatile Hydrocarbons – 25 ppm maximum
• Water Content – – High pressure cylinder air must have a dew point of at least -50o F (-45.6o C) and a water vapor content of 67 ppm maximum. NFPA 1500 regulations for Fire Department use may vary from OSHA requirements

How to Ensure you comply and meet the breathing air standards

Compliance will differ slightly based on the application you will be using breathing air for.  However, for each application most companies will offer equipment to properly meet the federal standard. You should verify with a reputable company for your given application what is required to properly meet the standard. For example to safely meet compressed air standards for sandblasting you would want to ensure you have a carbon monoxide monitor and then a proper air purifying filter unit like those that come with a Clemco blast pot and safety gear package. You can also consider a free air pump as an alternative which would eliminate the need for carbon monoxide monitoring. Your individual requirement will typically have similar requirements but it is always best to speak with a company that is well versed in your particular situation to ensure that the safety equipment offered will properly meet the safety requirements.