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Performance of Filtering Facepieces and Powered Air-purifying Respirators Challenged with Different Aerosols

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2016, PhD, University of Cincinnati, Medicine: Industrial Hygiene (Environmental Health).
The main objective of this research was to evaluate the performance of various respiratory protective devices (RPDs) against different aerosols. The tested devices included surgical masks, N95, R95, P95 and N100 filtering facepiece respirators (FFRs), and powered air-purifying respirators (PAPRs). Challenge aerosols included sodium chloride (NaCl) particles, combustion particles generated by burning of wood, paper and plastic materials, and surgical smoke generated by cutting the animal tissue. Sodium chloride particles were used as the “model” challenge aerosols, and the RPD performance data collected were compared to those obtained with real workplace aerosols. The effects of multiple factors such as challenge aerosol type, breathing flow rates including constant inhalation flow and cyclic flow, particle size, relative humidity of the ambient air, and respirator type on the RPDs’ performance were evaluated. This dissertation describes four related studies (A-D). In study A (Chapter 1), the filter samples of N95, R95 and P95 FFRs were challenged against NaCl particles and combustion particles generated by burning of wood, paper and plastic materials. The study revealed that the penetration of combustion particles was significantly higher than that of NaCl particles. However, this result was not observed for R95 and P95 FFR filters. Challenge aerosol type, constant inhalation flow rate, and particle size were significant factors on the filter performance of N95 FFR. In study B (Chapter 2), two models of N95 FFRs fully sealed on the manikin headform were tested against NaCl particles and plastic combustion particles. The tests were performed under two relative humidities, RH &asymp 20% and &asymp 80%, representing dry and moderately humid air conditions, respectively. Filter penetration decreased significantly with increasing RH. Challenge aerosol type, mean inspiratory flowrate (MIF), RH and respirator model have significant effect on the performance of tested N95 FFRs. The effect of particle size varied depending on the challenge aerosol and respirator model. In study C (Chapter 3), different RPD types including two surgical masks, two N95 FFRs, and two N100 FFRs were tested on ten human subjects exposed to surgical smoke. Simulated workplace protection factor (SWPF) was measured for each subject wearing an RPD. The study revealed that N95 FFRs and N100 FFRs offer much higher protection level than that of surgical masks while challenging with surgical smoke. Particle size was a significant factor only for the N100 FFRs. In study D (Chapter 4), improperly sized and stretched-out loose-fitting powered air-purifying respirators (PAPRs) donned on the manikin headform were challenged with NaCl particles. Results showed that the facepiece type and breathing flow rate were significant factors affecting the PAPR performance. Manikin fit factor (mFF) decreased with increasing breathing flows. The protection level of the stretched-out loose-fitting PAPR was significantly lower than the level offered by the other two improperly sized loose-fitting PAPR. Overall, our results could assist the manufacturers in designing better respirators. Additionally, the work provides database to regulatory agencies and respiratory protection researchers, which is important for developing guidelines for the selection of appropriate respirators at a workplace.
Sergey Grinshpun, Ph.D. (Committee Chair)
Pramod Kulkarni, D.Sc. (Committee Member)
Roy Mckay, Ph.D. (Committee Member)
Marepalli Rao, Ph.D. (Committee Member)
Tiina Reponen, Ph.D. (Committee Member)
222 p.

Recommended Citations

Citations

  • Gao, S. (2016). Performance of Filtering Facepieces and Powered Air-purifying Respirators Challenged with Different Aerosols [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1459155521

    APA Style (7th edition)

  • Gao, Shuang. Performance of Filtering Facepieces and Powered Air-purifying Respirators Challenged with Different Aerosols. 2016. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1459155521.

    MLA Style (8th edition)

  • Gao, Shuang. "Performance of Filtering Facepieces and Powered Air-purifying Respirators Challenged with Different Aerosols." Doctoral dissertation, University of Cincinnati, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1459155521

    Chicago Manual of Style (17th edition)