At Wageningen University, Maarten Krol is employed as a professor Air Quality and Atmospheric Chemistry at the department Meteorology and Air Quality (MAQ). Focus is on the modeling of the atmospheric composition on different spatial and temporal scales. Air quality is determined not only by the emission of pollutants, but also by atmospheric transformation, geographical location, and atmospheric transport. The research of Maarten Krol tries to understand and quantify different factors that determine the quality of the air. For city environments, it is often difficult to combine large economic activity with clean air. For Amsterdam, favorably located close to the North Sea, focus should be on clean transportation systems such as bike lines and good public transport.