Particle Count Statistics Applied to the Penetration of a Filter Challenged with Nanoparticles

Details

• Personal Author:
  O'Shaughnessy PT ; Schmoll LH
• Description:
  Statistical confidence in a single measure of filter penetration (P) is dependent on the low number of particle counts made downstream of the filter. This article discusses methods for determining an upper confidence limit (UCL) for a single measure of penetration. The magnitude of the UCL was then compared to the P value, UCL ≤ 2P, as a penetration acceptance criterion (PAC). This statistical method was applied to penetration trials involving an N95 filtering facepiece respirator challenged with sodium chloride and four engineered nanoparticles: titanium dioxide, iron oxide, silicon dioxide, and single-walled carbon nanotubes. Ten trials were performed for each particle type with the aim of determining the most penetrating particle size (MPPS) and the maximum penetration, P max. The PAC was applied to the size channel containing the MPPS. With those P values that met the PAC for a given set of trials, an average P max and MPPS was computed together with corresponding standard deviations. Because the size distribution of the silicon dioxide aerosol was shifted toward larger particles relative to the MPPS, none of the ten trials satisfied the PAC for that aerosol. The remaining four particle types resulted in at least four trials meeting the criterion. MPPS values ranged from 35 to 53 nm with average P max values varying from 4.0% for titanium dioxide to 7.0% for iron oxide. The use of the PAC is suggested for determining the reliability of penetration measurements obtained to determine filter P max and MPPS. [Description provided by NIOSH]
• Subjects:
  Aerosols Occupational Health Particulate Matter Personal Protective Equipment Respiratory Protective Devices Safety
• Keywords:
  Aerosol Particles Aerosol Sampling Filters N95 Filtering Facepiece Respirators Nanoparticles Particle Aerodynamics Particle Counters Particle Size
• ISSN:
  0278-6826
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Journal Article
• Place as Subject:
  Iowa ; OSHA Region 7
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Volume:
  47
• Issue:
  6
• NIOSHTIC Number:
  nn:20058720
• Citation:
  Aerosol Sci Technol 2013 Jan; 47(6):616-625
• Contact Point Address:
  Patrick T. O'Shaughnessy, Department of Occupational and Environmental Health, The University of Iowa, 105 River St., S320 CPHB, Iowa City, IA 52242-5000, USA
• Email:
  patrick-oshaughnessy@uiowa.edu
• Federal Fiscal Year:
  2013
• Performing Organization:
  University of Iowa
• Peer Reviewed:
  True
• Start Date:
  20050701
• Source Full Name:
  Aerosol Science and Technology
• End Date:
  20080630
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:8cc79d5403be5e3e496e5a09733410fc1082cf31e7891db45e4964673f85b11eebc534db8c0a4e17e04200651d0a20b131e2733285d5087ddab48df7eaa91149
• Download URL:
  https://stacks.cdc.gov/view/cdc/223121/cdc_223121_DS1.pdf
• File Type:
  [PDF - 532.99 KB ]