The regional and global air pollution problems discussed in this report are ozone formation in the troposphere, acid deposition, depletion of the stratospheric ozone layer and increasing greenhouse effect. Currently, the two most important air pollution problems related to aircraft emissions are oxidant formation and increasing greenhouse effect, in both cases mainly due to emissions of NOx. The acid deposition from aircraft emissions is not believed to be significant on global or regional scales. Depletion of the stratospheric ozone layer is neither a problem with the current fleet of aircraft. A proposed fleet of high flying aircraft in the future may however threaten the ozone layer.