The German National Academy of Sciences Leopoldina requests additional efforts to further reduce the concentration of pollutants in the air. More emphasis should be placed on particulate matter rather than nitrogen oxides. No significant relief is to be expected from short-term or small-scale measures, such as traffic bans. Rather, a nationwide cross-departmental strategy for air pollution control is required, according to the statement published in April 2019 entitled "Clean Air - Nitrogen oxides and particulate matter in the ambient air: Basic principles and recommendations". In the paper, the scientists point out that the emission of greenhouse gases is particularly problematic with regard to transportation and therefore call for a sustainable transport policy.