[en] The success of PIXE methods for resarch on chemical processes in the natural atmosphere depends on the identification of significant problems in air chemistry where the PIXE methods can be applied to advantage. In order to facilitate these applications in the future, the present state of knowledge is reviewed with respect to terrestrial dust, radioactive aerosols, sea spray, volcanic emmisions, biosphere emanations, biomass burning, and sulfur oxides in clean air. Some of this research has already been conducted using PIXE methods. (orig.)