Niu Jianjun, Rasmussen Pat E, Magee Robert, Nilsson Gregory
Environmental Health Science and Research Bureau, HECSB, Health Canada, Ottawa, Ontario K1A 0K9, Canada.
Environ Sci Process Impacts. 2015 Jan;17(1):98-109. doi: 10.1039/c4em00478g. Epub 2014 Nov 20.
This study deployed a suite of direct-reading instruments in six locations inside one building to characterize variability of the background aerosol, including incidental nanoparticles (NP), over a six month period. The instrument suite consisted of a portable Condensation Particle Counter (CPC) and a Scanning Mobility Particle Sizer (SMPS) for assessing particle number concentrations and size distributions in the nano-scale range; an Aerodynamic Particle Sizer (APS) for assessing micron-scale particle number concentrations and size distributions; plus a desktop Aerosol Monitor (DustTrak DRX) and a Diffusion Charger (DC2000CE) for assessing total particle mass and surface area concentrations respectively. In terms of number concentration, NPs (<100 nm) were the dominant particles observed in the background aerosol, contributing up to 53-93% of the total particle number concentrations. The particle size distributions were bimodal with maxima around 19-79 nm and 50-136 nm, respectively, depending on workplace locations. The average detected background particle number, surface area and total mass concentrations were below 7.1 × 10(3) # cm(-3), 22.9 μm(2) cm(-3) and 33.5 μg m(-3), respectively in spring samples and below 1.8 × 10(3) # cm(-3), 10.1 μm(2) cm(-3) and 12.0 μg m(-3), respectively in winter samples. A point source study using an older model laser printer as the emission source indicated that NPs emitted from the investigated printer were distinguishable from background. However, more recent low emitting printers are likely to be indistinguishable from background, and chemical characterization (e.g. VOCs, metals) would be required to help identify emission sources.
本研究在一栋建筑内的六个地点部署了一套直读仪器，以表征背景气溶胶（包括偶发纳米颗粒（NP））在六个月期间的变异性。该仪器套件包括一台便携式冷凝粒子计数器（CPC）和一台扫描迁移率粒径谱仪（SMPS），用于评估纳米尺度范围内的粒子数浓度和粒径分布；一台空气动力学粒径谱仪（APS），用于评估微米尺度的粒子数浓度和粒径分布；另外还有一台台式气溶胶监测仪（DustTrak DRX）和一台扩散充电器（DC2000CE），分别用于评估总粒子质量和表面积浓度。就数浓度而言，NP（<100 nm）是背景气溶胶中观测到的主要粒子，占总粒子数浓度的比例高达53 - 93%。粒径分布呈双峰型，最大值分别约为19 - 79 nm和50 - 136 nm，具体取决于工作场所位置。春季样本中检测到的背景粒子数、表面积和总质量浓度平均值分别低于7.1×10³ # cm⁻³、22.9 μm² cm⁻³和33.5 μg m⁻³，冬季样本中则分别低于1.8×10³ # cm⁻³、10.1 μm² cm⁻³和12.0 μg m⁻³。一项以一台较旧型号激光打印机作为排放源的点源研究表明，所研究打印机排放的NP与背景有明显区别。然而，最近的低排放打印机可能与背景难以区分，可能需要进行化学表征（例如挥发性有机化合物、金属）来帮助识别排放源。
