Current Issues in the Assessment of Respiratory Protective Devices for Occupational and Non-Occupational Uses Proceedings of a Workshop (2021) / Chapter Skim
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6 Assessment Pathways for Respiratory Protective Devices for the Public
6 Assessment Pathways for Respiratory Protective Devices for the Public
Pages 75-92
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From page 75... ...
In this session, moderated by planning committee member Daniel Shipp, retired from the International Safety Equipment Association, three speakers explored how existing conformity assessment (CA) processes may be used to provide respiratory protection for non-occupational use, specifically the use of these devices by the general public.
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From page 76... ...
Defining Respiratory Protective Devices Johnson explained that RPDs are devices that have been designed to provide the wearer with a specified level of respiratory protection against a defined hazard. RPDs can be divided into three types based on design and performance: (1)
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From page 77... ...
Johnson commented that exhalation valves are a type of impactor, which when opened can remove some of the particulate, especially large droplets, from an indi idual's exhaled airstream. He also v presented images of various types of masks and facial coverings, including a surgical face mask, non-surgical procedure face mask, comfort mask, and several types of facial coverings (see Figure 6-1)
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From page 78... ...
Bottom: Masks and facial coverings. NOTE: FDA = Food and Drug Administration.
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From page 79... ...
This can result in a false sense of security associated with the use of respiratory protection, he said, and poorly designed RPDs may be made with materials that actually contribute to the risk of exposure. Monograph Specifications for General-Purpose Face Coverings The collaborative efforts described by DenHartog led to the development of a voluntary draft monograph4 for the textile industry that offers 2 The voluntary standard is available at https://www.aatcc.org/guidance-for-making-a-better face-covering (accessed October 9, 2020)
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From page 80... ...
He noted that the monograph is now being further developed by ASTM International to provide more technical detail, background, and guidance. Particle Filtration Efficiency The voluntary draft suggests that for particle filtration efficiency,6 face coverings shall demonstrate a particle filtration efficiency of greater than 70 percent with maximum 3-micron particle size at a velocity of 10.4 cm/s.
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From page 81... ...
The fabric used in general- purpose cloth masks differs in important ways from the fabric used in N95s, he said. N95s are manufactured with non-woven, technical- ltration fabrics fi that have a different structure than woven fabrics and have additional electrostatic functionality to enhance filtration efficiency.
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From page 82... ...
PPE scientists who are accustomed to dealing with filtration efficiencies of 95–99.9 percent may be concerned by the low filtration efficiencies of cloth masks, he said. However, the high filtration standards for extant PPE devices are designed to protect indi iduals who are entering known hazardous environments v 10 DenHartog clarified that technically it is small droplets rather than aerosols that would be suspended in air for a longer period of time and that assessment involves looking at the smaller micron particle size.
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From page 83... ...
FIGURE 6-2 Particulate filtration efficiency of materials assessed through North Carolina State University's Textile Protection and Comfort Center's newly developed material-level evaluation. NOTE: Tests conducted using FLUKE 985 particle counter–0.1 cfm (2.8 L/min)
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From page 84... ...
DEVELOPING A STANDARD SPECIFICATION FOR BARRIER FACE COVERINGS Jonathan Szalajda, the deputy director of the National Personal Protective Technology Laboratory (NPPTL) at NIOSH, discussed opportunities to develop or support CA processes for RPDs and for source control strategies, such as cloth face coverings, that are responsive to the specific requirements of nontraditional user groups.
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From page 85... ...
Scope and Performance of ASTM 73471 The scope of the ASTM 73471 standard includes source control and the provision of some degree of inhalation protection. Emerging evidence suggest that face coverings may help to reduce transmission through source control, Szalajda said, and there is growing awareness that the types of face coverings currently being used vary in terms of effectiveness.
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From page 86... ...
For instance, they are looking at filtration requirements using the ASTM F-2100 standard and the NIOSH test procedure for N95 filtering facepiece efficiency. They are also considering the forthcoming ASTM standard for measuring fit (expected to be released in late 2020)
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From page 87... ...
DenHartog suggested developing some level of hazard assessment to determine appropriate standards and test methods, which would make it possible for certification to be conducted by private companies or through NPPTL. At that point public health and educational efforts could then support individuals in decision making related to the selection and use of products for different circumstances, he added.
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From page 88... ...
A participant asked whether a barrier face covering needs to perform similarly to a surgical N95 -- or perhaps at a lower protected factor -- in providing protection to the wearer and providing source control as a barrier to outgoing pathogen flow. In addition, the participant asked whether a face covering should also protect from environmental hazards such as smoke and air pollution.
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From page 89... ...
He added that the potential effects of exhalation valves come into play when the wearer has a higher breathing rate, which reduces breathing resistance. Elastomerics always open, he explained, as that is the mechanism for exhaled air to exit the elastomeric face piece.
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From page 90... ...
Instead of looking at the exhalation valve or at the fabric filtration in isolation, he suggested examining the mask overall and developing guidelines to certify masks. Reflections on the Session Shipp offered his reflections on the presentations and discussions of workshop Session 4B: Assessment Pathways for Respiratory Protective Devices and Other Options for the Public.
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From page 91... ...
. He concluded that although he agrees that "the perfect should not be the enemy of the good," particularly in terms of providing respiratory protection to the public, it is not necessarily the case that any protection is better than no protection.
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