Over its history, the composition of Earth’s atmosphere has varied, at times quite dramatically and with consequences for life on the planet. However, since the age of humans Earth's atmospheric composition has changed in unprecedented ways. This course discusses the chemistry of atmospheric processes and how human activity in altering the composition of the atmosphere drives chemical reactions that have consequences on human and ecosystem health. Chemical principles are applied towards understanding the chemistry of acid rain, smog, and stratospheric ozone depletion. The significance of chemical research in revealing molecular-level details of atmospheric chemical transformations and helping inform regulations such as the Clean Air Act in the US and the Montreal Protocol will be discussed through primary and secondary literature. The course culminates with a final project where the class explores the intersection of air quality and environmental justice. This course satisfies the Intermediate Level requirement for the IS major. Prerequisite: LSCI 2500 Chemistry of the Environment.