Reconstruction of Past and Prediction of Future Benzo[a]pyrene Concentrations Over Europe


Benzo[a]pyrene (BaP) is a highly carcinogenic substance that is created as an unintentional byproduct of combustion processes. In order to simulate the development of European BaP concentrations between 1980 and 2020 a consistent emission dataset for the time span 1980–2010 was created using the SMOKE-EU emission model. Moreover, a variety of different emission scenarios for the year 2020 was created to estimate the future development of BaP emissions. The emission datasets have been used as input for a modified version of the Chemistry Transport Model (CTM) CMAQ. This CMAQ version is to our knowledge the only regional CTM to include the heterogeneous reaction of particulate BaP with ozone which, besides wet deposition, is the main sink of atmospheric BaP. It was found that BaP concentrations have been decreasing strongly between 1980 and 2000. This is due to the large reduction of primary BaP emissions from industrial processes, residential wood and coal burning, and vehicle exhausts. Depending on the emission scenario, simulated BaP concentrations over Europe between 2000 and 2020 are changing by −25 to +5 %. Because further reduction of industrial BaP emissions is supposed to be low, the future development depends mainly on the amount of wood used for heat production. Also changes of emissions of ozone precursors showed to impact the degradation of BaP. Finally, several regions were identified in which the annual BaP target value of 1 ng/m3 was exceeded. In 1980 this was the case for the Po-valley, the Paris metropolitan area, the Rhine-Ruhr area, Vienna, and Madrid. Predictions for 2020 lead to exceedances in the Po-valley, the Paris metropolitan area, and Vienna.
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