Question: NFPA 99 2018 (2) indicates that medical air shall meet the requirements of medical air USP. However, Table does not include nitric oxide and sulfur dioxide as contaminates to be tested for even though they are listed in the USP as contaminates. Can you please help clarify why these are not required to be tested for in NFPA 99?

Answer: This is an interesting question that has been discussed for a very long time for a few reasons. I have been advocating that there be some testing for onsite medical air compressor systems at health care facilities in accordance with the USP standards for many years. Since it is required in the NFPA 99: Health Care Facilities Code that the medical air produced by these systems must meet the USP requirements, it seems reasonable to assume that the FDA would want to have a CGMP (Current Good Manufacturing Practice) to address the production of this medical gas onsite. This approach would be similar to the requirements for the manufacture and distribution of all of the other medical gases, which are regulated by the FDA.  NFPA 99 DOES require that the medical air meet the USP requirements in addition to the other contaminants listed in the code

If the above holds true, then a major question becomes when/how often is the testing required. Clearly, it is required for new systems. However, many verifiers do not test to the USP specification when conducting the commissioning of a new medical air compressor system, but only test for the contaminants listed specifically in NFPA 99. Our company’s SOP requires us to test to the USP specification for ANY new medical gas supply system.

We also recommend as a best practice (CGMP) that the medical air compressor system be tested at least quarterly for compliance with the USP specification and the NFPA 99 contaminants for medical air. Some of our clients prefer to do this monthly, but many only perform this test during an annual inspection. Others do not perform this testing ever!!! The FDA (nor any other US organization that I’m aware of) has not provided guidance on this issue.

What does everyone else do with testing protocols for these systems?

I just returned from conducting a training course in Columbia and they mostly follow the NFPA 99 requirements, as well as a set of government regulations, for their medical gas systems. Interestingly, they require that the medical air be continuously monitored for some of the contaminants (similar to our requirement for the CO and Dew Point monitors), but also require testing within every (8) days for compliance with the USP specification. In the event that the medical air from the compressor fails the USP test, the procedure would be to shut down the compressor system and there is requirement to have an emergency backup manifold system that would be used until the compressor system returns to producing the medical air in accordance with the USP and NFPA requirements.  Other countries have similar requirements for periodically testing these systems to ensure the medical air produced onsite is in compliance with the regulatory requirements and standards.

The system design above is similar to UK standards, which require tertiary systems. The US only requires duplex systems.