The design of most cities prioritizes the use of motorized vehicles, having a negative effect on urban health. A major concern in the European Union (EU) is air pollution, especially nitrogen dioxide (NO2), which causes many inhabitants health problems and decreases the quality of life. A non-expensive way to reduce pollutants is implementing road restriction policies, as the creation of low emission zones. In this work, we analyze the case of Madrid Central, a low emission zone deployed in Madrid, Spain. We evaluate if it was effective to reduce air pollutants and if there were a side effect, as pollution displacement, during its application. Drawing on open data, we analyze air quality at different points of the city, before and during the application of this measure. Taking into account the EU directives in terms of what healthy air means, we consider three metrics: (a) the trend of NO2 concentration in the air in both periods, (b) the difference between the NO2 concentration during both periods, and (c) the percentage of time in which the population is exposed to air with NO2 concentration under a specific threshold (healthy air as defined by the EU). According to the results, Madrid Central significantly reduces the NO2 concentration in the air and does not produce pollution displacement. Thus, the population breathes healthy air during more time, and there is a positive effect on the whole city.

中文翻译：

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改善城市健康的汽车限制政策：西班牙马德里的低排放区

大多数城市的设计优先使用机动车辆，对城市健康产生负面影响。欧盟 (EU) 的一个主要问题是空气污染，尤其是二氧化氮 (NO2)，它会导致许多居民的健康问题并降低生活质量。减少污染物的一种非昂贵方法是实施道路限制政策，如创建低排放区。在这项工作中，我们分析了马德里中心的案例，这是一个部署在西班牙马德里的低排放区。我们评估它在减少空气污染物方面是否有效，以及在其应用过程中是否有副作用，如污染置换。利用开放数据，我们分析了该措施实施之前和实施期间城市不同地点的空气质量。考虑到欧盟关于健康空气意味着什么的指令，我们考虑三个指标：(a) 两个时期空气中 NO2 浓度的趋势，(b) 两个时期 NO2 浓度之间的差异，以及 (c) 人口暴露于空气中的时间百分比NO2 浓度低于特定阈值（欧盟定义的健康空气）。根据结果​​，马德里中央显着降低了空气中的二氧化氮浓度，并且不会产生污染置换。因此，人们可以在更长的时间内呼吸健康的空气，对整个城市产生积极影响。(c) 人口暴露于 NO2 浓度低于特定阈值（欧盟定义的健康空气）的空气中的时间百分比。根据结果​​，马德里中央显着降低了空气中的二氧化氮浓度，并且不会产生污染置换。因此，人们可以在更长的时间内呼吸健康的空气，对整个城市产生积极影响。(c) 人口暴露于 NO2 浓度低于特定阈值（欧盟定义的健康空气）的空气中的时间百分比。根据结果​​，马德里中央显着降低了空气中的二氧化氮浓度，并且不会产生污染置换。因此，人们可以在更长的时间内呼吸健康的空气，对整个城市产生积极影响。