Research and reflections on European air pollution policy support models

Sammanfattning: European emissions to air of SO2, NOx, PM2.5, NH3 and NMVOC still today cause harm to human health and the environment. These pollutants are associated with the premature death of ~400 000 people annually in the EU (25 000 perished in traffic accidents 2017). Improvements are expected but problems will persist. To abate these effects European countries are engaged in several international agreements, all dependent on interaction between science and policy. For some 15 years scientific decision support to policy-makers was based on integrated assessment models (IAM) combined with quantification of economic benefits in cost-benefit analysis (CBA) of proposed policies. However, in 2013 the European Commission changed approach and used CBA to model socio-economic optimal emission levels and used these levels as basis for a policy proposal. This new approach puts higher demand on model coverage and reliability. It can also be methodologically controversial. This thesis presents research and reflections on the robustness of air pollution policy support models used by the European Commission, with focus on IAM and CBA. Robustness over climate metrics is analysed with cost-effectiveness analysis of air pollution control options, with sensitivity analysis of metric choice. An SO2 decomposition analysis indicates if consideration of end-of-pipe control options is enough. Robustness of emission control strategies with respect to investment parameters is analysed with IAM, and CBA provides estimates of whether options to reduce emissions from international shipping should be considered in the modelling. Methodological issues are also reviewed. The results indicate that the models are robust with respect to climate metrics used and the focus on end-of-pipe SO2 options. The modelling of emission control can be sensitive to investment parameters and to the current exclusion of control options on ships. The methodological foundation of CBA is criticised but since environmental policies depend on support also from arenas outside science it remains unclear if CBA-shortcomings impairs the air pollution policy process. Regardless, there are arguments for inter alia complementing CBA with analyses based on non-economic decision rationales. Finally, the thesis provides insights and suggestions for air pollution policy modelling and research that should be considered in the future.