Davis Mary E, Laden Francine, Hart Jaime E, Garshick Eric, Blicharz Andrew, Smith Thomas J
Department of Urban and Environmental Policy and Planning, Tufts University, Medford, Massachusetts 02155, USA.
J Occup Environ Hyg. 2009 Jul;6(7):396-403. doi: 10.1080/15459620902914349.
This study analyzes the temporal variability of occupational and environmental exposures to fine particulate matter in the U.S. trucking industry and tests the predictive ability of a novel multilayer statistical approach to occupational exposure modeling using structural equation modeling (SEM) techniques. For these purposes, elemental carbon mass in PM<1 microm at six U.S. trucking terminals were measured twice during the same season up to 2 years apart, observing concentrations in the indoor loading dock (median EC: period 1 = 0.65 microg/m(3); period 2 = 0.94 microg/m(3)) and outdoor background location (median EC: period 1 = 0.46 microg/m(3); period 2 = 0.67 microg/m(3)), as well as in the truck cabs of local drivers while on the road (median EC: period 1 = 1.09 microg/m(3); period 2 = 1.07 microg/m(3)). There was a general trend toward higher exposures during the second sampling trips; however, these differences were statistically significant in only a few cases and were largely attributable to changes in weather patterns (wind speed, precipitation, etc.). Once accounting for systematic prediction errors in background concentrations, the SEM approach provided a strong fit for work-related exposures in this occupational setting.
本研究分析了美国运输行业职业和环境中细颗粒物暴露的时间变异性，并使用结构方程模型（SEM）技术测试了一种新型多层统计方法对职业暴露建模的预测能力。为此，在长达两年的同一季节内，对美国六个运输码头直径小于1微米颗粒物中的元素碳质量进行了两次测量，观测了室内装卸区（元素碳中位数：第1阶段 = 0.65微克/立方米；第2阶段 = 0.94微克/立方米）、室外背景位置（元素碳中位数：第1阶段 = 0.46微克/立方米；第2阶段 = 0.67微克/立方米）以及当地司机在路上时卡车驾驶室内（元素碳中位数：第1阶段 = 1.09微克/立方米；第2阶段 = 1.07微克/立方米）的浓度。在第二次采样过程中，总体上存在暴露增加的趋势；然而，这些差异仅在少数情况下具有统计学意义，并且很大程度上归因于天气模式（风速、降水量等）的变化。一旦考虑到背景浓度中的系统预测误差，SEM方法对该职业环境中与工作相关的暴露情况具有很强的拟合度。
