Stephenson Dale, Seshadri Gauri, Veranth John M
University of Utah, Rocky Mountain Center for Occupational and Environmental Health, 75 South 2000 East, Salt Lake City, UT 84112-5120, USA.
AIHA J (Fairfax, Va). 2003 Jul-Aug;64(4):516-21. doi: 10.1202/394.1.
Particle emissions from manual shielded metal arc welding of carbon steel were sampled in a typical industrial maintenance and metal fabrication workplace environment. Particle number measurements over the size range from 14 nm to 10 microm using a scanning mobility particle sizer and an optical particle counter showed that welding produced an approximately lognormal particle mode with a 120 nm count median and a geometric standard deviation of 2.07. This study produced welding particle number concentrations on the order of 2 x 10(5)/cm(3) in the building air 8.5 m away from the welding. Workplace exposure samples were below the current 8-hour American Conference of Governmental Industrial Hygienists mass concentration threshold limit value of 5 mg/m(3). Submicron particles comprised 80% of the total aerosol mass collected by a cascade impactor during welding. The concentration of larger particles was indistinguishable from indoor background. Microscopy showed that the welding emissions are dominated by clusters formed from <0.1 microm primary spheres. These data on the particles resulting from aerosol transformation by natural dilution inside an industrial building can be compared with laboratory-scale studies of welding particulate. The particle number characteristics observed in this study are significant because toxicological hypotheses suggest that number or surface area may be a better metric than mass when evaluating the health effects of fine particles.
在典型的工业维护和金属制造工作场所环境中，对碳钢手工屏蔽金属弧焊产生的颗粒排放物进行了采样。使用扫描迁移率粒径谱仪和光学粒子计数器对粒径范围从14纳米至10微米的颗粒数量进行测量，结果表明，焊接产生了一种近似对数正态分布的颗粒模式，计数中位数为120纳米，几何标准差为2.07。本研究得出，在距离焊接点8.5米处的建筑空气中，焊接产生的颗粒数浓度约为2×10⁵/cm³。工作场所暴露样本低于美国政府工业卫生学家会议当前规定的8小时质量浓度阈限值5毫克/立方米。在焊接过程中，亚微米颗粒占串联冲击器收集的总气溶胶质量的80%。较大颗粒的浓度与室内背景浓度没有区别。显微镜检查表明，焊接排放物主要由直径小于0.1微米的初级球体形成的团簇组成。这些关于工业建筑内通过自然稀释实现气溶胶转化所产生颗粒的数据，可与焊接颗粒物的实验室规模研究进行比较。本研究中观察到的颗粒数量特征具有重要意义，因为毒理学假说表明，在评估细颗粒的健康影响时，颗粒数量或表面积可能是比质量更好的衡量指标。
