EMISSIONS AND AIR QUALITY IN URBAN AREAS OF GERMANY AN ACTUAL SURVEY

More tight emission limits and higher requirements on fuel quality have led to a de-crease in traffic emissions in urban areas in Germany despite an increase in vehicle mileage. This decrease also shows up in the development of urban air quality in respect to benzene and carbon monoxide (CO) at highly exposed streets. Measured values for these pollutants al-ready comply with future EU air quality standards. For nitrogen dioxide (NO2) and particu-late matter (PM10), however, no such decrease can be observed. Today’s air quality limits for PM10 as well as future air quality limits for NO2 will therefore be exceeded at many sites. For nitrogen oxides, the development of the calculated emissions is identical with the sum of all measured nitrogen oxide concentrations. While the concentrations of nitrogen monoxide decreased very strongly, NO2 values remained almost unchanged. For the pollutant concentration, however, besides the NOx emissions also the interaction with ozone and the amount of direct NO2 traffic emissions is of importance. These complex interdependencies can lead to an increase in NO2 concentrations despite a decrease in NOx emissions. The contribution of traffic emissions to a PM10 concentration varies much depending on the local and regional environment. Furthermore, the meteorological conditions have a con-siderable influence. Besides direct exhaust emissions also emissions from traffic abrasion and resuspension as well as secondary particles contribute to PM10 concentrations. Secondary particles are formed from nitrogen oxides, sulphur dioxide and ammoniac. These complex interactions have to be considered for an effective reduction of NO2 and PM10 concentrations. The identification of appropriate measures and modelling of respective effects therefore requires broad background knowledge as well as an elaborate methodology