Air pollution is no longer just a local issue; it is a global problem. The atmosphere is a very dynamic system. Pollution not only changes in chemical composition after it is emitted, but also is transported on local and global air systems hundreds and even thousands of miles away. Some of the pollutants that are major health concerns are not even emitted, but are formed during chemical reactions within the atmosphere. Tropospheric ozone reaches unhealthy levels in many urban and even rural areas during the summer. Measurements have revealed that ozone can reach extremely high abundances in rural areas, where crop and forest damage are of concern. In this article, the author discusses a four-part lesson that he has written in which students look at real data about pollution in their own states and counties.