Traffic-related activities are widely acknowledged as a primary source of urban ambient ultrafine particles (UFPs). However, a notable gap exists in quantifying the contributions of road and air traffic to size-resolved and total UFPs in urban areas. This study aims to delineate and quantify the traffic's contributions to size-resolved and total UFPs in two urban communities. To achieve this, stationary sampling was conducted at near-road and near-airport communities in Seattle, Washington State, to monitor UFP number concentrations during 2018–2020. Comprehensive correlation analyses among all variables were performed. Furthermore, a fully adjusted generalized additive model, incorporating meteorological factors, was developed to quantify the contributions of road and air traffic to size-resolved and total UFPs. The study found that vehicle emissions accounted for 29% of total UFPs at the near-road site and 13% at the near-airport site. Aircraft emissions contributed 14% of total UFPs at the near-airport site. Notably, aircraft predominantly emitted UFP sizes below 20 nm, while vehicles mainly emitted UFP sizes below 50 nm. These findings reveal the variability in road and air traffic contributions to UFPs in distinct areas. Our study emphasizes the pivotal role of traffic layout in shaping urban UFP exposure.

中文翻译：

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量化两个城市社区道路和空中交通对环境超细颗粒的贡献

交通相关活动被广泛认为是城市环境超细颗粒物 (UFP) 的主要来源。然而，在量化道路和空中交通对城市地区尺寸解析和总 UFP 的贡献方面存在显着差距。本研究旨在描述和量化两个城市社区中交通对尺寸分辨和总 UFP 的贡献。为了实现这一目标，我们在华盛顿州西雅图的公路附近和机场附近的社区进行了固定采样，以监测 2018 年至 2020 年期间的 UFP 数量浓度。对所有变量进行综合相关分析。此外，还开发了一个包含气象因素的完全调整的广义加性模型，以量化道路和空中交通对尺寸分辨和总 UFP 的贡献。研究发现，在靠近道路的地点，车辆排放占 UFP 总量的 29%，在靠近机场的地点，占 13%。飞机排放占机场附近 UFP 总量的 14%。值得注意的是，飞机主要发射 20 nm 以下的 UFP 尺寸，而车辆主要发射 50 nm 以下的 UFP 尺寸。这些发现揭示了不同地区道路和空中交通对 UFP 的贡献存在差异。我们的研究强调了交通布局在塑造城市 UFP 暴露方面的关键作用。