In this study, vehicle plume measurements from over 27,500 vehicles were made using continuous fast-response instruments located at the curbside for nitrogen oxides (NO_x), particle number (PN), and black carbon (BC) in the city of Milan, Italy. A recently developed plume regression technique is further enhanced to calculate highly disaggregated emission factors for a wide range of vehicle classes. The data reveal a strong improvement in the emissions performance for NO_x from passenger cars on going from laboratory to on-road testing. However, for emissions of PN and BC, disaggregation by vehicle manufacturers for diesel passenger cars highlights anomalously high emissions from some manufacturers. Emissions from one manufacturer, which predate on-road testing, are up to a factor of 4 higher than the average of other manufacturers and are among those being scrutinized in several European countries through enhanced periodic technical inspections (PTI) that for the first time considered PN. Near-road concentration source apportionment reveals a broader range of vehicle types contributing to PN and BC compared to NO_x. The top three contributors to NO_x concentrations account for 57% of total NO_x but only 28–29% of total PN and BC. These findings have implications for policies such as low-emission zones of the type adopted in Milan and elsewhere in the world. The combination of curbside measurements and plume regression allows for both high-resolution emission measurements and ambient concentration source apportionment.

中文翻译：

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使用羽流回归技术分析高度分解的颗粒物和气态车辆排放因子以及环境浓度分配

在这项研究中，使用位于意大利米兰市路边的氮氧化物 （NO_x）、颗粒数 （PN） 和黑碳 （BC） 的连续快速响应仪器对 27,500 多辆汽车的车辆羽流进行了测量。最近开发的羽流回归技术得到了进一步增强，可以计算各种车辆类别的高度分解排放因子。数据显示，从实验室到道路测试，乘用车的 NO_x 排放性能有了很大的改善。然而，对于 PN 和 BC 的排放，汽车制造商对柴油乘用车的分类突出了某些制造商的异常高排放。一家制造商的排放量在道路测试之前，比其他制造商的平均水平高出 4 倍，并且是几个欧洲国家通过加强定期技术检查 （PTI） 进行审查的排放量之一，PTI 首次被视为 PN。与 NO_x 相比，近路浓度源分配揭示了导致 PN 和 BC 的车辆类型范围更广。NO_x 浓度的前三个贡献者占总 NO_x 的 57%，但仅占总 PN 和 BC 的 28-29%。这些发现对米兰和世界其他地方采用的低排放区等政策具有影响。路边测量和羽流回归相结合，可实现高分辨率排放测量和环境浓度源分配。