Buzzard Neil A, Clark Nigel N, Guffey Steven E
Department of Mechanical and Aerospace Engineering, West Virginia University, Engineering Sciences Building, Evansdale Drive, Morgantown, WV 26506, USA.
Environ Health. 2009 Mar 30;8:13. doi: 10.1186/1476-069X-8-13.
Inhalation of diesel particulate matter (DPM) is known to have a negative impact on human health. Consequently, there are regulations and standards that limit the maximum concentrations to which persons may be exposed and the maximum concentrations allowed in the ambient air. However, these standards consider steady exposure over large spatial and time scales. Due to the nature of many vehicle exhaust systems, pedestrians in close proximity to a vehicle's tailpipe may experience events where diesel particulate matter concentrations are high enough to cause acute health effects for brief periods of time.
In order to quantify these exposure events, instruments which measure specific exhaust constituent concentrations were placed near a roadway and connected to the mouth of a mannequin used as a pedestrian surrogate. By measuring concentrations at the mannequin's mouth during drive-by events with a late model diesel truck, a representative estimate of the exhaust constituent concentrations to which a pedestrian may be exposed was obtained. Typical breathing rates were then multiplied by the measured concentrations to determine the mass of pollutant inhaled.
The average concentration of diesel particulate matter measured over the duration of a single drive-by test often exceeded the low concentrations used in human clinical studies which are known to cause acute health effects. It was also observed that higher concentrations of diesel particulate matter were measured at the height of a stroller than were measured at the mouth of a mannequin.
Diesel particulate matter concentrations during drive-by incidents easily reach or exceed the low concentrations that can cause acute health effects for brief periods of time. For the case of a particularly well-tuned late-model year vehicle, the mass of particulate matter inhaled during a drive-by incident is small compared to the mass inhaled daily at ambient conditions. On a per breath basis, however, the mass of particulate matter inhaled is large compared to the mass inhaled at ambient conditions. Finally, it was determined that children, infants, or people breathing at heights similar to that of a passing vehicle's tailpipe may be exposed to higher concentrations of particulate matter than those breathing at higher locations, such as adults standing up.
已知吸入柴油颗粒物（DPM）会对人体健康产生负面影响。因此，存在相关法规和标准来限制人员可能接触的最大浓度以及环境空气中允许的最大浓度。然而，这些标准考虑的是在大空间和时间尺度上的稳定接触。由于许多车辆排气系统的特性，靠近车辆排气管的行人可能会经历柴油颗粒物浓度高到足以在短时间内造成急性健康影响的情况。
为了量化这些接触事件，将测量特定排气成分浓度的仪器放置在道路附近，并连接到用作行人替代物的人体模型的嘴部。通过在一辆新型柴油卡车驶过期间测量人体模型嘴部的浓度，获得了行人可能接触的排气成分浓度的代表性估计值。然后将典型呼吸率乘以测量浓度，以确定吸入的污染物质量。
在单次驶过测试期间测量的柴油颗粒物平均浓度经常超过人类临床研究中已知会导致急性健康影响的低浓度。还观察到，在婴儿车高度处测量的柴油颗粒物浓度高于在人体模型嘴部测量的浓度。
驶过事件期间的柴油颗粒物浓度很容易达到或超过可能在短时间内造成急性健康影响的低浓度。对于一辆特别调校良好的新型车辆而言，驶过事件期间吸入的颗粒物质量与在环境条件下每日吸入的质量相比很小。然而，就每次呼吸而言，吸入的颗粒物质量与在环境条件下吸入的质量相比很大。最后确定，儿童、婴儿或呼吸高度与过往车辆排气管高度相似的人可能比在较高位置呼吸的人，如站立的成年人，接触到更高浓度的颗粒物。
