What You Should Know About CMAS Applicability Testing

If you are a chemical manufacturer and have been keeping a pulse on the federal air quality rules, you may have heard about the CMAS rule.

What is CMAS? It is the National Emission Standards for Hazardous Air Pollutants (NESHAP) for chemical manufacturing area sources (CMAS) that is codified under 40 CFR Part 63, Subpart VVVVVV. The rule was originally finalized in 2009 and changes were proposed in January 2025. If you own or operate a chemical manufacturing process unit that is located at an area source of hazardous air pollutants (HAPs) or a HAP is used as a feedstock for your chemical process, CMAS may apply to you.

If you think that your facility may be subject to the CMAS rule, what are the next steps? To tell whether your facility is subject to the CMAS rule, you must have analytical data to assess whether your facility is or is not subject to the rule. To get this analytical data, you must collect and analyze samples. To execute the measurements, you must develop a test plan. Finally, you must assess and summarize the data and draw a conclusion. The first step in assessing the CMAS rule’s applicability to your facility is to create a test plan.

CMAS samples often differ from other environmental samples in key ways. Oftentimes, established environmental sampling and analytical methods don’t apply to the process streams. These methods were not developed with complex chemical process streams in mind, and the sample matrices can be very complex. There may be instances where the sampling and analysis methods will need to be modified to obtain meaningful measurements. Not all laboratories will be able to accept the sample due to safety concerns, and not all laboratories will be capable of implementing the necessary method modifications. It’s important to communicate what is being sampled and how the data are to be used to make sure that the lab is able to analyze the samples as collected for the specified analytes. Sometimes samples will have many related compounds in a stream that can muddy the analytical results, so it’s important for the facility and the lab to continue communicating as the program moves from sampling to analysis.

A successful test plan should consider a few different aspects of the testing program. Any test plan should have a clearly defined goal. That will make sure that as other considerations and challenges come into play, decisions are made to best achieve the goal. For the purpose of this article, the goal is to determine CMAS applicability. Understanding the complexity of the task in front of you, the test plan will want to reflect input from the facility, a sampling team, and an analytical laboratory.

The selection of a testing firm and/or an analytical laboratory are key. This selection should be a dialogue between the facility, the tester, and the analytical laboratory. The facility should be able to communicate the expected analytes to be found in the material and any expected challenges or considerations. This assessment of expected analytes is essential for test plan development. While in many cases a test plan can be developed without input from a sampling or analytical group, that is not the case for CMAS applicability.

This leads us to finally detailing our comprehensive plan for the actual sampling and analysis of the samples. In our example, a CMAS applicability consideration would require both the chemical process feed streams and the exhaust gas streams to be sampled. As the details are hammered out, the following questions are addressed:

• Are there any hazards associated with gathering samples at either location?
• What methods will be used?
• Will the samples need to be preserved, either chemically or thermally?
• Will the samples be stable enough to be analyzed in the time it takes for the lab to receive it?
• Are there any transportation hazards that need to be accounted for?

ALL4’s chemical sector team is well-versed in all aspects of evaluating applicability of the chemical sector air rules, preparing gap analyses, and developing compliance plans. If you need help putting together a test plan for your applicability determination, or if you’ve already started working through your testing program and want assistance on how to navigate the ongoing dialogue between your facility, your testing firm, and your laboratory, feel free to contact me at tcunningham@all4inc.com.