Global Atmospheric Chemical Change

Air pollution has historically been viewed as a local or regional scale problem with attention focused on acute episodes such as the sulphur dioxide and smoke smogs of London in the 1950s and 1960s and the photochemical smogs of southern California first recognized by Haagen­ Smit in the early 1950s. In recent years, however, it has become apparent that human activity has, and still is, changing t...