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U.S. Food and Drug Administration

Modified Adult Manikin Fit (MAMF) Test Method for Assessing Re-used and/or Decontaminated N95 Respirators

Catalog of Regulatory Science Tools to Help Assess New Medical Devices 

This regulatory science tool is a laboratory method for measuring fit-factor of re-used and/or decontaminated N95 respirators using adult manikins. 

Technical Description

This regulatory science tool provides a pre-clinical test method to evaluate the fit of re-used and/or decontaminated N95 respirators. The National Institute for Occupational Safety and Health’s (NIOSH) existing adult manikin fit evaluation method can be used to assess new or decontaminated N95 respirators; Medical Device Reports (MDRs) submitted to FDA have suggested a possible need for modification of the NIOSH method to allow for the measurement of fit factor for re-used and/or decontaminated N95 respirators. 

Intended Purpose 

This tool can be used by medical device manufacturers or facilities that decontaminate N95 respirators prior to reuse to determine a quantitative ‘manikin fit-factor’ of FDA-cleared surgical respirators (product code MSH) when they are re-used and/or decontaminated. The user of this tool should have some level of familiarity with respiratory protection programs within their organizations, and should be familiar with Occupational Safety and Health Administration’s (OSHA) fit testing procedures given the complexity of fit-testing measurements. 

Testing

The following testing has been conducted as part of the development  of the test method as outlined in the supporting documentation1: 

  1. Testing of manikin fit matches that of fit testing performed on human subjects with multiple (up to 5 times) consecutive donning and doffings. 
  2. Comparison of percentage of fit tests with fit factor > 100 between manikin fit test and compared with human fit tests up to 20 times. 
  3. Testing of manikin fit compared to human fit with 1 cycle of moist heat microwave decontamination with three brands of N95 respirators. 
  4. Testing of manikin fit compared to human fit with 1 cycle of autoclave decontamination with two brands of N95 respirators. 

Limitations

  • Different factors (e.g., facial dimensions) can impact the fit and seal of a respirator on different individuals. The use of a medium headform provides a standardized approach for evaluating respirator fit and allows for comparisons across different models and brands. 
  • Biocompatibility, filtration and breathability of the N95 respirators were outside the scope of this tool.  

Supporting Documentation

The tool is described in the following peer reviewed article: 

  1. Hasani, A., Dawson, J., Fogarasi M., Snodderly, K., Porter, D., Guha, S. Modifying NIOSH’s Manikin Fit Evaluation Method to Match Fit Testing with Human Subjects. Journal of International Society for Respiratory Protection, 2023; 40(2): 1-14. https://pmc.ncbi.nlm.nih.gov/articles/PMC11478269/ 
  2. Please refer to the User Manual and STL files for further instructions on how to print the headform and perform manikin fit-testing. The STL files can be accessed here – doi.org/10.6084/m9.figshare.25330738 

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