10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
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Evaluation of Portable Instruments for Measuring Nanoparticles Exposure and Respirator Performance under Simulated Workplace Conditions
ZIQING ZHUANG, Evanly Vo, Matthew Horvatin, NIOSH
Abstract Number: 398 Working Group: Aerosol Exposure
Abstract Recent advances in aerosol instrument technology have made it possible to produce small, light, and portable format instruments for measuring aerosol particles, especially nanoparticles under laboratory conditions. Questions have emerged regarding the field use of portable instruments. These include: 1) how to wear these portable aerosol instruments while workers conduct their normal work without any interferences, 2) how to operate and perform across different body positions (bending, side-to-side reaching, and movement), and 3) how these instruments can withstand workplace environments. Thus, the aim of this study was to develop a new method of evaluation for portable instruments, including the handheld condensation particle counter (CPC), portable aerosol mobility spectrometer (PAMS), optical particle sizer (OPS), and NanoScan scanning mobility particle sizer (NanoScan SMPS) for measuring nanoparticles exposure and respirator performance under simulated workplace conditions.
The portable instruments were mounted to a tactical load bearing vest or backpack and carried on the back of the test subject while conducting simulated workplace activities. Simulated workplace protection factors (SWPFs) were measured using human subjects exposed to NaCl aerosols. Before beginning a SWPF test for a given respirator model, each of 10 subjects had to pass a quantitative fit test. Each SWPF test was performed using a protocol of five exercises for three minutes each: 1) normal breathing while standing, 2) deep breathing, 3) bending at the waist, 4) walking gently in place, and 5) a simulated laboratory-vessel cleaning motion. Two particle devices of each field portable instrument type and two SMPSs were used simultaneously to measure the upstream (outside the respirator) and downstream (inside the respirator) test aerosol. SWPF was then calculated as a ratio of the upstream and downstream particle concentrations. The results of the SWPF study show that geometric mean SWPF (GM-SWPF) was highest for the NanoScan OPS combined, followed by PAMS, and CPC.
This study demonstrated that NanoScan OPS, PAMS, and CPC could be used for measuring nanoparticle exposures under simulated workplace conditions. This study also provided the advantages and limitations of each individual portable instrument when 1) wearing it while workers conduct their normal work, 2) performing across different body positions (bending, side-to-side reaching, and movement), and 3) determining how each instrument can withstand workplace environments. Therefore, the results from this study could be used with appropriate caution, when selecting a suitable portable instrument for aerosol particle measurement and evaluation of respirator performance in nanotechnology workplaces.