Development of an Animatronic Headform Test Method for the Evaluation of Fit and Total Filtration Efficiency of Barrier Face Coverings

Details

• Personal Author:
  Armistead MK
• Description:
  The COVID-19 pandemic has had widespread implications. Early supply shortages made it difficult to obtain traditional respiratory protection. The general public was advised to instead wear medical masks or barrier face coverings as a method of source control. These products offer variable efficacy depending on their material, fit to the face, and the environment in which they are worn. Recent studies and standards tend to evaluate these products at the material level or as a sealed product which does not account for leakage around the perimeter of the barrier due to poor fit when worn. This research focused on developing a system-level method to realistically assess the performance of these products that are not designed to seal to the face. An advanced animatronic headform with breathing and movement capabilities was used to evaluate the total filtration efficiency of several respiratory devices, medical masks, and barrier face coverings. The baseline headform method was able to clinically and statistically differentiate between samples. The respiratory flow rate, testing duration, and operator were shown to significantly impact filtration while the influence of movement was less conclusive. The variance component estimates confirmed that the method had good repeatability and reproducibility. A closer analysis across particle sizes was able to compare the fit to the headform. The filtration efficiency measured with the baseline method was compared to the recent ASTM F3502-21 Standard Specification for Barrier Face Coverings. This standard evaluated the samples as a sealed product which eliminated leakage from the measurement. There was a notable decrease in filtration efficiency on the headform compared to the ASTM method due to the incorporation of fit into the measurement that offered a more realistic assessment of daily wear. However, both methods generally agreed on the product classification levels for a large percentage of the samples suggesting similarities between the two measurements. From this analysis, an optimized headform method was developed to reduce the variability within samples. The animatronic headform was moved into an environmental chamber that allowed for temperature and humidity control. The condensed protocol was still able to statistically differentiate between samples across the three product groups. The measured total filtration efficiency was significantly lower with the optimized method for each sample along with their coefficient of variation from the mean. The variance component estimates demonstrated that the new method improved repeatability. This study offered an alternative method to traditional material and system-level evaluations that was able to realistically evaluate the performance of barrier face coverings and other products on a headform. [Description provided by NIOSH]
• Subjects:
  Communicable Diseases Filtration Laboratories Occupational Health Personal Protective Equipment Respiratory System Safety
• Keywords:
  COVID-19 Filter Materials Fit Testing Laboratory Techniques Respiratory Equipment
• Publisher:
  North Carolina State University
• Document Type:
  Text
• Funding:
  Contract
• Genre:
  Thesis
• Place as Subject:
  North Carolina ; OSHA Region 4
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  1-163
• NIOSHTIC Number:
  nn:20068693
• Citation:
  Raleigh, NC: North Carolina State University, 2023 Jan; :1-163
• Federal Fiscal Year:
  2023
• Performing Organization:
  North Carolina State University
• Peer Reviewed:
  False
• Start Date:
  20210315
• Source Full Name:
  Development of an animatronic headform test method for the evaluation of fit and total filtration efficiency of barrier face coverings
• End Date:
  20230514
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:9407f226fa69a923557ca8c73e9c49a76625d371dfdfafadb19fb9692228b38f3d0101dcd22094e9f3c6ee9639463e44007d227584da65a54b2bcf57b7f27812
• Download URL:
  https://stacks.cdc.gov/view/cdc/207283/cdc_207283_DS1.pdf
• File Type:
  [PDF - 5.56 MB ]