AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
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Assessing Respirator Protection Factor with Novel Personal Devices
MARGARET SIETSEMA, Thomas Peters, Allison Persing, K.R. Farmer, University of Iowa
Abstract Number: 532 Working Group: Instrumentation and Methods
Abstract Background: Respirators are worn by medical professionals, emergency responders, construction workers and industrial workers to reduce their inhalation exposure to aerosols. A fit test is performed when a respirator is initially assigned to a worker and annually thereafter to assess the protection the respirator provides. Quantitative fit testing is typically conducted using the TSI PortaCount®, a single-channel bench-top device that uses an alcohol-based condensation particle counting system to measure the particle concentration inside and outside of the respirator.
Aim: To evaluate two new, compact (<0.8 kg, <950 cm3) and wearable dual channel particle counters that would enable real-time respirator fit evaluation. One instrument uses a dual channel optical particle counter (DC-OPC) while the other uses a dual channel water-based CPC (DC-CPC) to measure particle concentrations simultaneously inside and outside the respirator facepiece.
Methods: Respirator fit factors measured simultaneously from a PortaCount® (real-time mode), the DC-OPC, and the DC-CPC were compared for one test subject for three aerosols (ambient, sodium chloride, and smoke) over a range of protection factors and aerosol concentrations. The experiments were run using a 3M 65021HA1-C Household Multi-Purpose Respirator with P100 organic vapor cartridges. During testing, three OSHA accepted activities for determining a fit factor were performed, including normal breathing, deep breathing, and moving the head side to side.
Results: The DC-CPC correlates well with the PortaCount® over a wide range of protection factors up to at least 2000, ambient aerosol concentrations and aerosol types. Second-by-second protection factor variations due to breathing or other changes in the subject’s activity are captured by the DC-CPC and correlate well (R2>0.8) with fluctuations measured by the PortaCount®. In contrast, the DC-OPC has a limited functional range in ambient concentrations between ~10,000 and ~40,000 p/cm3 and for protection factors less than ~100.