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CHRISTOPHER COFFEY is associate director for science at the NIOSH National Personal Protective Technology Laboratory in Morgantown, W. Va.
COLLEEN MILLER is the deputy branch chief of the Conformity Verification and Standards Development Branch at the NIOSH National Personal Protective Technology Laboratory in Pittsburgh, Pa.
JONATHAN SZALAJDA is deputy director of the NIOSH National Personal Protective Technology Laboratory in Morgantown, W. Va. Send feedback to The Synergist.
A New Standard for Respirator Fit
BY CHRISTOPHER COFFEY, COLLEEN MILLER, AND JONATHAN SZALAJDA
In observance of the 100th anniversary of the publication of the first U.S. Bureau of Mines respirator approval schedule, NIOSH published “The Respirator Fit Capability Test: Enhancing the Efficacy of Filtering Facepiece Respirators” as a digital supplement to the September 2019 issue of The Synergist. The article described the development of a new voluntary ASTM International standard designed to help ensure negative-pressure half-facepiece particulate respirators fit a percentage of wearers. Here, we provide an update on the status of this standard.
DEVELOPMENT OF ASTM F3407-20
As stated in “The Respirator Fit Capability Test,” the draft standard was first balloted in April 2019 by ASTM Subcommittee F23.65. There were three negative votes. Based on the input received during the June 2019 subcommittee meeting, the draft standard was revised and all comments were addressed. A second ballot in April 2020 resulted in two negative and three affirmative votes with comments. The negative comments addressed issues such as the passing rate for the respirator fit capability (RFC) test, which the commenters thought was too low; the test chamber variables; the placement of the in-facepiece probe; the effects of other types of personal protective equipment (such as safety glasses) on the fit of the respirator; details of the talking exercise, one of several exercises that test subjects perform; the addition of a requirement that manufacturers post the results of the RFC test for each passing respirator model; and use of the NIOSH bivariate panel, a tool for classifying the facial dimensions of respirator wearers. The comments received with the affirmative ballots discussed the formatting of the standard and suggested that it provide examples of probed elastomeric facepieces and of the equipment needed to conduct the testing.
ASTM F3407-20 will enable respirator manufacturers to develop models that fit a greater portion of the worker population.
The F23.65 subcommittee found all comments associated with the negative ballots to be non-persuasive. An appeal challenging this determination was denied, and on Oct. 13, 2020, ASTM F3407-20, Standard Test Method for Respirator Fit Capability for Negative-Pressure Half-Facepiece Particulate Respirators, was published. It is available for purchase from the ASTM International website. The only differences between the draft described in the September 2019 article and the final standard are editorial. NIOSH is designing a study to be completed within the next three years that will determine the precision of the method and the necessity of the grimace exercise.
BENEFITS OF THE STANDARD ASTM F3407-20 will enable respirator manufacturers to develop models that fit a greater portion of the worker population. Respirators that pass the RFC standard are expected to have better fitting characteristics—that is, they will fit more people, and wearers will be able to find an adequately fitting respirator with fewer fit tests. The standard will lower costs to respiratory protection programs since one respirator model is expected to adequately fit more workers in the program. Conformity assessment program owners such as NIOSH will be able to use the RFC standard to evaluate conventional respirator designs as well as novel ones. An example of a novel design is a respirator that does not include a head harness—straps that provide tension during use and even distribution of pressure. Assessment based on the RFC standard could ensure the novel design provides adequate tension and distributes pressure evenly over the entire area in contact with the face.
In conclusion, this standard defines performance requirements that could be used as part of a conformity assessment program to ensure that certified respirators or families of respirators are capable of fitting a specified percentage of their intended user population. This improvement in worker protection is essential in all industries where workers are exposed to a variety of agents (particles) and is critically important as new designers and manufacturers begin to make respirators. And the standard will be particularly helpful for protecting frontline workers in the healthcare industry during the COVID-19 pandemic.
RESOURCE
The Synergist: “The Respirator Fit Capability Test: Enhancing the Efficacy of Filtering Facepiece Respirators” (September 2019).