Effects of CO<SUB align=right><SMALL>2</SMALL></SUB> emission reduction strategies on air pollution

Emission reduction strategies for air pollutants such as SO<SUB align="right"><SMALL>2</SMALL></SUB> and O<SUB align="right"><SMALL>x</SMALL></SUB> as well as for greenhouse gases (GHGs) usually do not consider the interdependencies between emission reduction measures. Taking into account the relevant energy, environmental and political framework it is the objective of this study to determine the influence of CO<SUB align="right"><SMALL>2</SMALL></SUB> emission reduction strategies for the German state of Baden-Wurttemberg on emissions of SO<SUB align="right"><SMALL>2</SMALL></SUB> and NO<SUB align="right"><SMALL>x</SMALL></SUB>. Furthermore, effects on SO<SUB align="right"><SMALL>2</SMALL></SUB> and NO<SUB align="right"><SMALL>x</SMALL></SUB> emissions in Baden-Wurttemberg resulting from the implementation of an EU-wide trading of carbon dioxide emission allowances will be analysed. Therefore, the study is based on the development and application of an energy and material flow model for Baden-Wurttemberg with the help of which future developments in different sectors (e.g. energy supply, households, industry) are analysed. Different assumptions with respect to the economic and political framework are considered. The model results show that a CO<SUB align="right"><SMALL>2</SMALL></SUB>-reduction causes a considerable reduction of the pollutant SO<SUB align="right"><SMALL>2</SMALL></SUB> and to a smaller extent of the pollutant NO<SUB align="right"><SMALL>x</SMALL></SUB>. This is due to the fact that the substantial measures necessary for a limitation of CO<SUB align="right"><SMALL>2</SMALL></SUB> emissions are the increased use of natural gas and renewable energies in the energy supply sector as well as better insulation and efficient heating systems in the household sector. Furthermore, linking the model for Baden-Wurttemberg to an international power and emissions trading model shows that pollution emitters from Baden-Wurttemberg would buy CO<SUB align="right"><SMALL>2</SMALL></SUB>-certificates, resulting in a reduction of CO<SUB align="right"><SMALL>2</SMALL></SUB> mitigation costs but also in higher emissions of CO<SUB align="right"><SMALL>2</SMALL></SUB>, SO<SUB align="right"><SMALL>2</SMALL></SUB> and NO<SUB align="right"><SMALL>x</SMALL></SUB> in Baden-Wurttemberg compared to the scenario without emission trading. Finally, model results taking into account methodologies to evaluate different GHGs show that the integration of measures for the reduction of non-CO<SUB align="right"><SMALL>2</SMALL></SUB> GHGs also results in an increase of air pollution compared to the CO<SUB align="right"><SMALL>2</SMALL></SUB> reduction scenario.