Abstract Many European cities suffer from poor air quality and still exceed the European standards prescribed by the Air Quality Directive, and the guidelines recommended by the World Health Organization (WHO). This is especially the case for PM2.5, focus of this work. While international, national and local level actions to reduce air pollution have undoubtedly resulted in an overall improvement of the air quality over the years, there are still problems, which are localised in specific regions and many cities. A key issue is to determine at which scale to act in order to abate these remaining air pollution problems most effectively. Central to this, for cities, is a quantitative assessment of the different origins of air pollution (urban, regional, national and transboundary) to support the design of efficient, effective air quality plans, which are a legal obligation for countries and regions whenever exceedances occur. The “Screening for High Emission Reduction Potentials for Air quality” tool (SHERPA) is used in this work to quantify the origins of air pollution in cities and regions, both from a spatial (urban, country…) and sectoral (transport, residential, agriculture…) perspectives. For PM2.5 we conclude that (1) for many cities, local actions at the city scale are an effective means of improving air quality in that city; (2) the target sectors and scales to abate air pollution are city specific, even for cities that are located in the same country. Consequently, it is important to take into account these city-specific circumstances when designing air quality plans and (3) for many cities, sectoral measures addressing agriculture at country or EU scale would have a clear benefit on urban air quality.

中文翻译：

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欧洲城市 PM 2.5 来源分配：SHERPA 建模研究

摘要 欧洲许多城市空气质量不佳，仍然超过空气质量指令规定的欧洲标准和世界卫生组织（WHO）推荐的指南。对于 PM2.5 尤其如此，这是这项工作的重点。虽然多年来国际、国家和地方各级减少空气污染的行动无疑使空气质量得到了整体改善，但仍然存在一些问题，这些问题存在于特定地区和许多城市。一个关键问题是确定采取何种规模的行动以最有效地减轻这些剩余的空气污染问题。对于城市而言，其核心是对空气污染的不同来源（城市、区域、国家和跨界）进行定量评估，以支持设计高效、有效的空气质量计划，每当发生超标时，这是国家和地区的法律义务。“筛选空气质量的高减排潜力”工具 (SHERPA) 用于从空间（城市、国家……）和部门（交通、住宅、农业……）观点。对于 PM2.5，我们得出以下结论：（1）对于许多城市而言，城市规模的地方行动是改善该城市空气质量的有效手段；(2) 减少空气污染的目标部门和规模是特定于城市的，即使是位于同一国家的城市。因此，在设计空气质量计划时考虑这些城市特定情况很重要，并且 (3) 对于许多城市，