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Toward better fitting respirators.

Pittsburgh, PA: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Contract 2008-Q-10205, 2009 Jul; :1-56
Respirator fit and the value of fit testing are the least understood and most controversial aspects of respirator performance. Research has shown that fit testing is necessary to assure that respirators are properly worn and provide a preliminary level of expected protection. It is not yet possible, however, to identify or predict which combination of facial features and respirator design characteristics will assure both initial and long-term fit. This project was conducted by the University of Minnesota for the National Personal Protective Technology Program at the National Institute for Occupational Safety and Health, in response to a Request for Quotations (2008-Q-10205) seeking recommendations for research, procedures and policies leading to improvements in the fit of half-mask air purifying respirators. Two research tasks were undertaken: 1) an evaluation of barriers and incentives for recent innovations in respirator design and fit test methods and 2) conduct of a workshop to explore new ideas and research directions for better fitting respirators. This project was focused on recommendations for future NIOSH actions that might lead to improvements in respirator fit, not on the elimination of the need for fit testing. Four successful innovations (the ambient aerosol quantitative fit test method, strap cradle or head harness, double-flanged facepiece and flat fold design for filtering facepiece respirators) and two less successful innovations (adhesive face seal and user seal checks) were selected. Literature reviews, patent searches and interviews were conducted for each innovation. Interviews sought information on incentives for development, costs of development and marketing, effect on respirator use and regulation, effect of regulations, reasons for success (or not) and effect on respirator fit. Eleven platform and 13 poster presentations were included in the one-day workshop held on November 6, 2008 in Pittsburgh Pennsylvania. Workshop participants attended three breakout sessions and offered ideas about new materials and design, new fit test methods and knowledge gaps about fit. There have been numerous important improvements in both respirator design and fit test methods over the past 30-40 years. In most cases, technology push or market pull (or both) played an important role in the success of the innovations we examined; regulations generally had a neutral, or, in a few cases, limiting effect on their adoption. Researchers and research publications can play an important role in the adoption of an innovation. Published comparisons of new with current products or methods can encourage adoption; lack of publications can lead to skepticism about efficacy and slower adoption. Health and safety professionals, who rely on published research, user input and personal experience, can also encourage or discourage adoption of new products or methods. There continues to be high potential for innovation in design and fit test methods for better-fitting respirators. Success depends on a combination of specialized knowledge (of materials and technology), preliminary and supporting research, significant financial support, regulatory assistance and flexibility, and ultimately, health and safety professional and user acceptance. Recommendations are offered in the following areas of research: Recommendation 1.1: Conduct research to clarify the role of respirator design (technologies, materials and systems) in respirator fit, particularly with respect to strap designs, methods for facepiece cooling, methods for inducing positive pressure inside the facepiece, improvements that lower breathing resistance, and technologies and materials for improving facepiece seals. Recommendation 1.2: Conduct research to clarify the influence of facepiece design, multiple facepiece sizes and aging on the interaction between facial measurements and respirator fit. Recommendation 1.3: Conduct research on the role of user seal checks in establishing respirator fit, particularly for filtering facepiece respirators. Recommendation 1.4: Conduct research on new methods for checking facepiece seals. In particular, efforts should be made to identify methods that continuously track and report facepiece fit. Recommendation 1.5: Conduct research to elucidate the effect on respirator fit of a) other types of personal protective equipment (PPE) and b) environmental conditions such as temperature, relative humidity and dust. Recommendations are also offered to NIOSH to ensure implementation and incorporation of research findings into its programs and activities: Recommendation 2.1: Quantitative assessments of respirator fit using a human test panel should be included in the certification requirements of all half-mask negative pressure air purifying respirators. Recommendation 2.2: Consultative panel(s) representing key stakeholders - including respirator users and program managers, inventors, researchers, and manufacturers - should be used to ensure a forum for identifying issues, exchanging ideas, discussing research findings and defining future research directions. Recommendation 2.3: Collaborations among government agencies should be continued to combine resources for supporting internal and external research that is responsive to common needs. Recommendation 2.4: A formal assistance program should be developed to provide financial and other types of support to inventors and small businesses seeking to bring new ideas to market. Recommendation 2.5: A method should be established for conducting regular reviews of certification regulations in light of new technologies for respirator design and performance. Recommendation 2.6: More opportunities should be available, in addition to stakeholder meetings, for interactions between internal NIOSH researchers and external investigators.
Respirators; Respiratory-equipment; Respiratory-protective-equipment; Personal-protective-equipment; Protective-equipment; Testing-equipment; Equipment-design; Equipment-reliability; Anthropometry; Face-masks; Air-purifying-respirators; Self-contained-breathing-apparatus; Regulations; Physiological-measurements; Air-pressure; Breathing; Airway-resistance; Environmental-factors; Temperature-effects; Humidity; Relative-humidity; Dusts
Lisa M. Brosseau, ScD, CIH, University of Minnesota, School of Public Health, Division of Environmental Health Sciences, MMC 807, 420 Delaware Street, SE, Minneapolis MN 55455
Publication Date
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Final Contract Report
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National Institute for Occupational Safety and Health
Performing Organization
University of Minnesota, Minneapolis, Minnesota
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division