A drastic decline of 2.4 ppbv decade −1 in the ozone mixing ratio has been measured in Santiago de Chile during the 2000s. Subsequently, in the 2010s, ozone trends stabilized in downtown and showed upward trends in eastern Santiago. The number of days with an 8-h average ozone mixing ratio above 61 ppbv, deemed harmful to health according to Chilean legislation, has declined significantly both in western and central Santiago. However, in eastern Santiago, one finds a 2010–2018 decade average of 43 days per year above recommended levels. Also, at a Receptor Site located ~ 70 km downwind from Santiago, this number rose to up to 3 months per year. A common denominator for the last two decades has been a steady increase in both gasoline and diesel-powered private cars. In the 2010s, the ozone weekend effect was frequently noted, providing evidence that the ozone formation regime in Santiago is VOC-limited. Nitrogen oxides and carbon monoxide (a proxy of anthropogenic VOCs) have increased steadily since 2014 in a relatively constant CO-to-NO x ratio. Therefore, we propose that primary emissions of NO X and VOCs from motor vehicle exhaust have remained as the main driver of the photochemical air pollution in Santiago as well as explaining the weekly variation. Santiago, like other megacities in the world, faces several challenges associated with increasing urbanization as well as the effects of climate change. An increasing population, growth in private car use, and urban sprawl have contributed to maintain high levels of ozone. New threats such as increasing temperatures observed in the central valleys of Chile, along with more frequent occurrences of heat waves, whose number has doubled in the last decade, will require a different approach to manage ozone pollution during the next decade. Santiago will not meet its own goals in the upcoming years without implementing robust, scientifically sound, and cost-effective strategies designed specifically to tackle photochemical pollution.

中文翻译：

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智利圣地亚哥 20 年的臭氧超标情况

在 2000 年代，智利圣地亚哥的臭氧混合比急剧下降了 2.4 ppbv 十年 -1。随后，在 2010 年代，市中心的臭氧趋势趋于稳定，圣地亚哥东部则呈上升趋势。根据智利法律，8 小时平均臭氧混合比高于 61 ppbv 的天数在圣地亚哥西部和中部均显着下降，根据智利立法，该天数被视为对健康有害。然而，在圣地亚哥东部，人们发现 2010 年至 2018 年的十年平均每年 43 天高于推荐水平。此外，在位于圣地亚哥下风约 70 公里处的受体站点，这一数字上升至每年 3 个月。过去二十年的一个共同点是汽油和柴油动力私家车的稳步增长。在 2010 年代，经常注意到臭氧周末效应，提供证据表明圣地亚哥的臭氧形成机制受 VOC 限制。自 2014 年以来，氮氧化物和一氧化碳（人为 VOC 的代表）以相对恒定的 CO 与 NO x 比率稳步增加。因此，我们认为机动车尾气中 NO X 和 VOCs 的主要排放仍然是圣地亚哥光化学空气污染的主要驱动因素，并解释了每周变化。圣地亚哥与世界上其他特大城市一样，面临着与城市化进程加快以及气候变化影响相关的若干挑战。不断增长的人口、私家车使用的增长和城市扩张都导致臭氧保持在高水平。新的威胁，例如在智利中部山谷观察到的温度升高，以及更频繁发生的热浪，其数量在过去十年中翻了一番，未来十年需要采用不同的方法来管理臭氧污染。如果不实施专为解决光化学污染而设计的稳健、科学合理且具有成本效益的战略，圣地亚哥将无法在未来几年实现自己的目标。