Details:

Alternative Title:
Ann Occup Hyg
Personal Author:
Rengasamy, Samy ; Walbert, Gary ; Newcomb, William ; Coffey, Christopher ; Wassell, James Terrence ; ... More +
Rengasamy, Samy ; Walbert, Gary ; Newcomb, William ; Coffey, Christopher ; Wassell, James Terrence ; Szalajda, Jonathan Less -
Description:
A previous study used a PortaCount Plus to measure the ratio of particle concentrations outside (C out) to inside (C in) of filtering facepiece respirators (FFRs) worn by test subjects and calculated the total inward leakage (TIL) (C in/C out) to evaluate the reproducibility of the TIL test method between two different National Institute for Occupational Safety and Health laboratories (Laboratories 1 and 2) at the Pittsburgh Campus. The purpose of this study is to utilize the originally obtained PortaCount C out/C in ratio as a measure of protection factor (PF) and evaluate the influence of particle distribution and filter efficiency. PFs were obtained for five N95 model FFRs worn by 35 subjects for three donnings (5 models × 35 subjects × 3 donnings) for a total of 525 tests in each laboratory. The geometric mean of PFs, geometric standard deviation (GSD), and the 5th percentile values for the five N95 FFR models were calculated for the two laboratories. Filter efficiency was obtained by measuring the penetration for four models (A, B, C, and D) against Laboratory 2 aerosol using two condensation particle counters. Particle size distribution, measured using a Scanning Mobility Particle Sizer, showed a mean count median diameter (CMD) of 82 nm in Laboratory 1 and 131 nm in Laboratory 2. The smaller CMD showed relatively higher concentration of nanoparticles in Laboratory 1 than in Laboratory 2. Results showed that the PFs and 5th percentile values for two models (B and E) were larger than other three models (A, C, and D) in both laboratories. The PFs and 5th percentile values of models B and E in Laboratory 1 with a count median diameter (CMD) of 82 nm were smaller than in Laboratory 2 with a CMD of 131 nm, indicating an association between particle size distribution and PF. The three lower efficiency models (A, C, and D) showed lower PF values than the higher efficiency model B showing the influence of filter efficiency on PF value. Overall, the data show that particle size distribution and filter efficiency influence the PFs and 5th percentile values. The PFs and 5th percentile values decreased with increasing nanoparticle concentration (from CMD of 131 to 82 nm) indicating lower PFs for aerosol distribution within nanoparticle size range (<100 nm). Further studies on the relationship between particle size distribution and PF are needed to better understand the respiratory protection against nanoparticles.
Subjects:
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Aerosols Air Pollutants, Occupational Equipment Design Filtration Humans Inhalation Exposure Materials Testing N95 Respirators Nanoparticles Occupational Exposure Particle Size Reproducibility Of Results Respiratory Protective Devices
Source:
Ann Occup Hyg. 59(3):373-381
Pubmed ID:
25429023
Pubmed Central ID:
PMC4589166
Document Type:
Journal Article
Funding:
CC999999/Intramural CDC HHS/United States
Name as Subject:
National Institute for Occupational Safety and Health
Place as Subject:
United States
Collection(s):
CDC Public Access
Main Document Checksum:
[+]
urn:sha256:abdd3421bd6997bfb47eb2a4e9a233ded99cb29fe3fc58e2c68bba886cc0437d
Download URL:
https://stacks.cdc.gov/view/cdc/34632/cdc_34632_DS1.pdf
File Type:

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