Overview of the ASTM F3407 Standard Test Method for Respirator Fit Capability

The Fundamental Importance of Fit

One of the most important criteria for any filtering facepiece air-purifying respirator to be effective is that a good seal is formed between the respirator’s facepiece and the wearer’s skin. The ability to achieve this seal is called the respirator’s fitting characteristic.

In 1995, when NIOSH put Title 42 Code of Federal Regulations Part 84 (42CFR84) into operation, it did not include an evaluation of the fitting characteristics of respirators approved only for particulates.¹ In addition, no voluntary consensus or other government-unique standards existed to evaluate the fit capability of a filtering facepiece respirator prior to it being used in the workplace in an OSHA-regulated fit testing program. Therefore, several studies have been conducted to determine how well NIOSH-approved particulate respirators, especially filtering facepiece respirators, fit wearers.^2-8 These studies found a high number of filtering facepiece respirators on the market at the time had poor fitting characteristics. Filtering facepiece respirators that do not fit most employees place an unacceptable burden on respirator program administrators, who must then provide many models and sizes to ensure that every wearer can find a respirator that fits properly.⁹ In addition, poorly fitting respirators increase the number of fit tests required, increasing costs.¹⁰

ASTM International Develops a Voluntary Consensus Standard

To address the need for a fitting characteristic evaluation in the standards, NIOSH requested that ASTM International develop a voluntary consensus standard. ASTM International accepted the challenge, and requested that NIOSH, as leaders in conducting personal protective equipment research for the nation, chair the committee. This approach to standards development is consistent with the National Technology Transfer and Advancement Act of 1995, which directs federal agencies to use consensus standards to address policy objectives and activities where practical.¹¹

ASTM International developed the ASTM F3407 – 20 Standard Test Method for Respirator Fit Capability for Negative-Pressure Half-Facepiece Particulate Respirators (RFC Standard), which was published on October 13, 2020.¹² The purpose of the RFC standard is to increase the probability that available respirators fit a general worker population. Respirators meeting this standard will still have to be fit tested in the workplace on each wearer as required by the Occupational Safety and Health Administration (OSHA).¹³ The RFC Standard does not guarantee that a respirator will fit every wearer.

To test the fitting characteristics, the RFC Standard uses 25 human subjects with various face sizes using the NIOSH Bivariate Panel representing the U.S. civilian workforce.¹⁴ The subjects enter a chamber containing a sodium chloride (salt) aerosol and perform eight exercises. Equipment counts the salt particles present in the environment of the chamber and those that leaked into the facepiece. The number of particles that have leaked into the respirator is divided into the number of particles outside the respirator in the chamber to get each subjects RFC Standard results. To pass, a subject must achieve an RFC Standard result of at least 100. An RFC Standard result of 100 means that the number of particles outside the respirator is 100 times greater than inside. At least 13 of 25 (50%) test subjects must obtain an RFC result of 100 or greater for the respirator model to pass the RFC test. The testing procedure is described in more detail in a 2019 Synergist article.¹⁵

The RFC Standard is Expected to Have a Significant Impact

The ASTM RFC Standard will enable respirator manufacturers to develop better designed models that fit the worker population. Respirators passing the RFC Standard test method are expected to have better fitting characteristics. The RFC standard will lower costs to respiratory protection programs by reducing the number of different models needed in the program. Purchasers of particulate-only respirators could reference ASTM F3407 in their procurement packages to ensure receiving those with good fitting characteristics. The RFC Standard can be used by organizations, such as NIOSH, to ensure a minimum performance level of for all respirators used within an approval program.¹⁶ Both conventional respirator designs as well as novel respirators (such as ones without the prevalent two-strap head harness to provide adequate tension during use and even distribution of pressure) can be evaluated using the RFC standard.¹⁹

Ultimately, this RFC Standard defines performance requirements that could be used as part of a conformity assessment program to ensure that NIOSH-approved respirators will fit a specified percentage of the intended user population, thus providing workers with better protection. This is crucial in all industries in which workers are exposed to a variety of agents, one of the most notable examples being the Healthcare and Social Assistance industry sector. Healthcare workers may be exposed to biological agents, e.g., seasonal influenza, Ebola, Severe Acute Respiratory Syndrome (SARS), Influenza A H1N1, and more recently SARS-CoV-2, the virus that causes COVID-19, as well as to chemical agents.^17-19

ASTM F3407 can be read for free at https://www.astm.org/COVID-19/ or purchased at https://www.astm.org/search/fullsite-search.html?query=Respirator%20fit%20capability.

How do you think your company or industry could use the RFC standard to improve your respiratory protection program?

Christopher Coffey, PhD, is a former Associate Director for Science for the NIOSH National Personal Protective Technology Laboratory. (retired)

Lisa M Brosseau, ScD, CIH is a respiratory protection consultant and retired professor from the University of Illinois at Chicago (UIC) School of Public Health

Bonnie Rogers, DrPH, RN is a Professor adjunct Department of Environmental Sciences and Engineering, North Carolina Occupational Safety and Health Education and Research Center School of Public Health, University of North Carolina at Chapel Hill.

Jonathan Szalajda, MS, is the Deputy Director of the NIOSH National Personal Protective Technology Laboratory.

References

1. ‘‘Respiratory Protective Devices,’’ Federal Register 60:110 (8 June, 1995). p. 30336.
2. Duling MG, Lawrence RB, Slaven JE, Coffey CC. (2007) Simulated Workplace Protection Factors for Half-Facepiece Respiratory Protective Devices. J Occup Environ Hyg 4:420-431.
3. Lawrence RB, Duling MG, Calvert CA, Coffey CC. (2006) Comparison of Performance of Three Different Types of Respiratory Protection Devices. J Occup Environ Hyg 3:465-474.
4. Coffey CC, Lawrence RB, Campbell DL, Zhuang Z, Calvert CA, Jensen PA. (2004) Fitting Characteristics of Eighteen N95 Filtering-Facepiece Respirators. J Occup Environ Hyg 1:262-371.
5. Zhuang Z, Coffey CC, Lawrence RB. (2004). The Effect of Ambient Aerosol Concentration and Exercise on PortaCount™ Quantitative Fit Factors. J Inter Soc Respir Protect 21:11-20.
6. Coffey CC, Campbell DL, Zhuang Z (1999). Simulated workplace performance of N95 respirators. Am Ind Hyg Assoc J 60:618-624.
7. Reponen T, Lee SA, Grinshpun SA, Johnson E, McKay R. (2011) Effect of fit testing on the protection offered by N95 filtering facepiece respirators against fine particles in a laboratory setting. Annals of Occupational Hygiene. 55(3):264-71,
8. NIOSH [2010] NIOSH Investigation of 3M Model 8000 Filtering Facepiece Respirators as Requested by the California Occupational Safety and Health Administration, Division of Occupational Safety and Health. By Berry Ann, R. Cincinnati, OH: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Health Hazard Evaluation Report 2010-0044-3109, https://www.cdc.gov/niosh/hhe/reports/pdfs/2010-0044-3109.pdf.
9. OSHA Title 29 CFR 1910.134, Appendix A—Fit Testing Procedures. Available at https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.134AppA. Accessed on November 6, 2020.
10. Campbell DL; Coffey CC; Lenhart SW. “Respiratory protection as a function of respirator fitting characteristics and fit-test accuracy, Am Ind Hyg Assoc J 2001 Jan/Feb; 62(1):36-44.
11. National Technology and Advancement Act of 1995. Pub, L. No. 104-133. 15 USC 3701 (1996). Available at https://www.govinfo.gov/content/pkg/PLAW-104publ113/pdf/PLAW-104publ113.pdf. Accessed on January 25, 2021.
12. ASTM F3407-20 Standard Test Method for Respirator Fit Capab OSHA. Title 29 CFR 1910.134 – Respiratory Protection. Available at https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.134. Accessed on November 6, 2020.ility for Negative-Pressure Half-Facepiece Particulate Respirators. Available at https://www.astm.org/Standards/F3407.htm. Accessed on November 8, 2020.
13. OSHA. Title 29 CFR 1910.134 – Respiratory Protection. Available at https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.134. Accessed on November 6, 2020.
14. Zhuang, B. Bradtmiller and R.E. Shaffer (2007). New Respirator Fit Test Panels Representing the Current U.S. Civilian Work Force, Journal of Occupational and Environmental Hygiene, 4:9, 647-659.
15. Coffey C; Miller C. The respirator fit capability test: enhancing the efficacy of filtering facepiece respirators. Synergist 2019 Sep; 2019(9): Digital Extra. https://synergist.aiha.org/201909-respirator-fit-capability-test.
16. NIOSH [2017]. National framework for personal protective equipment conformity assessment – infrastructure. By D’Alessandro M. Pittsburgh, PA: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication 2018–102.
17. National Institute for Occupational Health and Safety NIOSH], Workplace Health and Safety Topics: Healthcare Available at https://www.cdc.gov/niosh/topics/healthcare/.
18. BLS (Bureau of Labor Statistics) (2018). Career guide to industries: Health care. http://www.bls.gov/oco/cg/cgs035.htm).
19. Occupational Safety and Health Administration [OSHA], 2015; Occupational Safety and Health Administration, National Institute for Occupational Safety and Health (2015). Hospital respiratory protection toolkit, Publication # 2015-117.