National Personal Protective Technology Laboratory, National Institute for Occupational Safety and Health, Pittsburgh, Pennsylvania.
AECOM, Amentum, Management Services, Aiken, South Carolina.
J Occup Environ Hyg. 2020 May;17(5):231-242. doi: 10.1080/15459624.2020.1735640. Epub 2020 Apr 3.
The aim of this study was to develop a new method to measure respirator protection factors for aerosol particles using portable instruments while workers conduct their normal work. The portable instruments, including a set of two handheld condensation particle counters (CPCs) and two portable aerosol mobility spectrometers (PAMSs), were evaluated with a set of two reference scanning mobility particle sizers (SMPSs). The portable instruments were mounted to a tactical load-bearing vest or backpack and worn by the test subject while conducting their simulated workplace activities. Simulated workplace protection factors (SWPFs) were measured using human subjects exposed to sodium chloride aerosols at three different steady state concentration levels: low (8x10 particles/cm), medium (5x10 particles/cm), and high (1x10 particles/cm). Eight subjects were required to pass a quantitative fit test before beginning a SWPF test for the respirators. Each SWPF test was performed using a protocol of five exercises for 3 min each: (1) normal breathing while standing; (2) bending at the waist; (3) a simulated laboratory-vessel cleaning motion; (4) slow walking in place; and (5) deep breathing. Two instrument sets (one portable instrument {CPC or PAMS} and one reference SMPS for each set) were used to simultaneously measure the aerosol concentrations outside and inside the respirator. The SWPF was calculated as a ratio of the outside and inside particles. Generally, the overall SWPFs measured with the handheld CPCs had a relatively good agreement with those measured with the reference SMPSs, followed by the PAMSs. Under simulated workplace activities, all handheld CPCs, PAMSs, and the reference SMPSs showed a similar GM SWPF trend, and their GM SWPFs decreased when simulated workplace movements increased. This study demonstrated that the new design of mounting two handheld CPCs in the tactical load-bearing vest or mounting one PAMS unit in the backpack permitted subjects to wear it while performing the simulated workplace activities. The CPC shows potential for measuring SWPFs based on its light weight and lack of major instrument malfunctions.
本研究旨在开发一种新方法，使用便携式仪器在工人进行正常工作时测量气溶胶粒子的呼吸器保护因数。便携式仪器包括一组两个手持式凝结核计数器 (CPC) 和两个便携式气溶胶迁移率光谱仪 (PAMS)，并用一组两个参考扫描迁移率粒子粒径仪 (SMPS) 进行了评估。便携式仪器安装在战术负重背心或背包上，由测试对象在进行模拟工作场所活动时佩戴。使用暴露于氯化钠气溶胶的人体受试者在三个不同的稳态浓度水平下测量模拟工作场所保护因数 (SWPF)：低 (8x10 个/厘米)、中 (5x10 个/厘米) 和高 (1x10 个/厘米)。在开始进行呼吸器的 SWPF 测试之前，需要有 8 位受试者通过定量拟合测试。每个 SWPF 测试使用五个练习进行协议，每个练习持续 3 分钟：(1) 站立时正常呼吸；(2) 弯腰；(3) 模拟实验室容器清洁动作；(4) 原地慢走；和 (5) 深呼吸。两组仪器 (每组一组便携式仪器 {CPC 或 PAMS} 和一组参考 SMPS) 用于同时测量呼吸器内外的气溶胶浓度。SWPF 计算为外部和内部粒子的比值。通常，手持式 CPC 测量的总体 SWPF 与参考 SMPS 测量的 SWPF 具有相对较好的一致性，其次是 PAMS。在模拟工作场所活动下，所有手持式 CPC、PAMS 和参考 SMPS 都显示出相似的 GM SWPF 趋势，随着模拟工作场所运动的增加，其 GM SWPF 降低。本研究表明，在战术负重背心内安装两个手持式 CPC 或在背包内安装一个 PAMS 单元的新设计允许受试者在进行模拟工作场所活动时佩戴它。CPC 具有测量 SWPF 的潜力，因为它重量轻且没有重大仪器故障。
