The subject of the project is the introduction of regulation on passenger cars to limit air pollution in cities, which have been discussed in many European cities, where different models have been introduced. The complex actor-network in Copenhagen is investigated and the primary barrier for a translation is found to be the resistance from the national politicians. This can be overcome by introducing interessement devices to the network, such as an EU lawsuit, enlightenment of the citizens, and/or socioeconomic calculations and cost-benefit analyses. This could get all actants to agree to the OPP and reach the mobilisation, where it is important that all actants continue to support the translation and introduce the neccesary measures.