ORD Eyes Adapting Draft Water PFAS Method To Measure Air Emissions
Inside EPA PFAS Policy, December 16, 2022— by Sam Hess (reposted with permission)
An EPA staffer told the Air & Waste Management Association's information exchange here earlier this month that officials in ORD and the Office of Air Quality Planning & Standards (OAQPS) are considering potentially revising a method currently used to measure PFAS from stationary sources, and possibly adapting a draft method for measuring PFAS in other media.
ORD and OAQPS, which originally collaborated on developing “other test method 45” (OTM-45), are continuing to evaluate its effectiveness and look for any potential needed revisions, the staffer said.
OTM-45 is currently a completed method used for measuring approximately 50 per- and polyfluoroalkyl substances (PFAS) in air, and is characterized by ORD as a “consistent” method that may “support a variety of monitoring applications, which include the analysis of multiple short-chain PFAS” that cannot be measured in other current methods, according to a 2021 EPA document.
While the method has not been subject to federal rulemaking, EPA's website says it can be considered for use in federally enforceable state and local programs, such as the issuance of Title V permits, state implementation plans, or as an approved alternative method for national emission standards for hazardous air pollutants (NESHAP), NESHAPs for source categories, or for standards of performance for new stationary sources.
This method is specifically used to measure what the ORD staffer referred to as “polar semi volatile” PFAS, which includes perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA).
Such measures are especially needed for addressing PFAS in air as agency officials have long said their lack of credible methods for measuring the contaminants in ambient air is a key factor delaying their ability to regulate.
“We are struggling” to find methods and measurements for PFAS “that we can actually believe,” Richard Shores, a top agency research official, told the agency's Board of Scientific Counselors (BOSC) last year.
The issue is of particular concern when it comes to incineration, as the technology is generally unable to destroy PFAS, which are produced in part for their ability to withstand extreme temperatures, and could even create new chemicals of concern through reactions in the atmosphere.
As a result of such concerns, lawmakers have temporarily blocked the Defense Department from using incineration to destroy large quantities of firefighting foam containing PFAS.
Further pressuring the agency to quickly advance test methods for PFAS in air, the Government Accountability Office (GAO), in a report issued earlier this year urged EPA to quickly finalize OTM-45, saying it would a “good starting point” for monitoring PFAS levels after incineration, which is a controversial process for the disposal of the chemicals.
Finalizing OTM-45 could “support optimization of full-scale disposal and destruction technologies” for PFAS, according to the GAO report.
The GAO report was requested by key lawmakers -- including Sens. Gary Peters (D-MI) and Tom Carper (D-DE), the chairmen of the Senate homeland security and environment committees, respectively.
Draft Method 1633
As part of its effort to improve its air measurement methods, EPA is evaluating whether there is a way to measure PFAS emissions using approaches in the agency's draft method 1633, which measures PFAS concentrations for non-drinking water sources such as surface water, groundwater, wastewater, biosolids, landfill leachate, and others.
Draft method 1633, which EPA has said it plans to finalize by the end of the year, was developed by the Office of Water and the Defense Department's Strategic Environmental Research and Development Program.
The ORD staff member noted the benefit of being able to use this method to measure air emissions is that it is more vetted than OTM-45 and because both methods measure the same PFAS compounds, being able to use just one method would provide a benefit to commercial labs, which could reduce the amount of testing they conduct.
OTM-45 presents a number of challenges simply based on its operation, such as maintaining probe and filter operating temperatures, sample preservation and hold times, obtaining appropriate materials, and others, the staff member said.
ORD and OAQPS are currently taking comments regarding user feedback, which could then help inform further revisions to the method.
The next steps for OTM-45 include a continuation of current work, as well as looking into ways to clarify and revise the method based on user feedback and facility field evaluations. The office also plans to put out an FAQ document once it finalizes its revisions, the staff member said.
Other Test Methods
While OTM-45 is the most complete method to date in measuring PFAS in air emissions from stationary sources, the staff member also highlighted some other test methods that are currently works in progress, identifying what kinds of considerations the office is making when it comes to crafting a successful test method.
The staff member said that successful test methods can account for diverse measurement applications, such as being used for multiple types of sources and measurement needs, characterizing a target list of known compounds of interest and measuring PFAS as a class.
Current methods target only a small number of PFAS compounds for analysis while significantly more may be present, and so a focus on identifying what might also be there is just as important as measuring for what compounds are known to be there, the staff member said, noting that “you don't find what you don't look for.”
ORD is currently evaluating how to include a nontargeted analysis in its other test method 50 (OTM-50), which is being developed to measure for nonpolar volatile PFAS. This method looks specifically at samples containing PFAS that are collected and analyzed from pyrolysis, combustion and incineration sources.
There are currently 30 per- and polyfluorocarbon targets that this method aims to measure for, and in addition to developing nontargeted analysis to identify new compounds for measurement, the staff member added that sensitivity levels and stability of the measurements is what has been key to developing the current list of target compounds, and will be helpful going forward.
In the future, EPA intends to include a requirement for commercial laboratories to create a report for any tentatively identified compounds and are continuing to evaluate options for measurement sensitivity improvements, the staff member said. -- Sam Hess (email@example.com)
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