Megacities are metropolitan areas with populations over 10 million, and many of them are facing significant global environmental challenges such as air pollution. Intense economic and human activities in megacities result in air pollution emissions, inducing high levels of air pollutants in the atmosphere that harm human health, cause regional haze and acid deposition, damage crops, influence regional air quality, and contribute to climate change. Since the Great London Smog and the first recognized episode of Los Angeles photochemical smog seventy years ago, substantial progress has been achieved in improving the scientific understanding of air pollution and in developing emissions reduction technologies and control measures. However, much remains to be understood about the complex processes of atmospheric transport and reaction mechanisms; the formation and evolution of secondary particles, especially those containing organic species; and the influence of emerging emissions sources and changing climate on air quality and health. Molina (DOI: 10.1039/D0FD00123F) has provided an excellent overview of the sources of emissions in megacities, atmospheric physicochemical processes, air quality trends and management, and the impacts on health and climate for the introductory lecture of this Faraday Discussion.

中文翻译：

---

结束语：关于大城市空气质量的法拉第讨论

特大城市是人口超过1000万的大都市地区，其中许多正面临着重大的全球环境挑战，例如空气污染。特大城市中激烈的经济和人类活动导致空气污染排放，导致大气中高浓度的空气污染物危害人体健康，引起区域雾霾和酸沉降，损害作物，影响区域空气质量，并助长气候变化。自从70年前的“伦敦大烟雾”和第一个公认的洛杉矶光化学烟雾事件以来，在提高对空气污染的科学认识以及开发减排技术和控制措施方面已经取得了实质性进展。但是，关于大气传输和反应机理的复杂过程，还有很多事情要理解。次生颗粒的形成和演化，尤其是含有机种的颗粒；以及新兴排放源和气候变化对空气质量和健康的影响。Molina（DOI：10.1039 / D0FD00123F）在本演讲的介绍中，对大城市的排放源，大气物理化学过程，空气质量趋势和管理以及对健康和气候的影响进行了出色的概述。法拉第讨论。