Assessing ozone abatement strategies in terms of their effectiveness on the regional and urban scales

Integrated ozone abatement strategies should take into account that an emis sion intervention which is effective on the regional scale may not necessar ily be effective for a city and its surroundings. In the context of a study performed for the European Commission a methodology was developed for asse ssing ozone abatement strategies in terms of their effectiveness on both th e regional and the urban scale. Towards this aim, the assumptions made for three regional emission reduction scenarios were assumed to be valid also f or the emission situation in the urban areas of Athens and Stuttgart and th e corresponding emission inventories were compiled. The EMEP MSC-W ozone mo del was used to calculate the regional scale ozone distribution over a 6 mo nth summer period applying the 1990 meteorology. Local scale transport and chemical transformation processes were analysed with the ozone fine structu re (OFIS) model. Both the regional and the local scale simulations were per formed for the base case (1990 situation) and the three emission reduction scenarios. The significance of regional scale emission reductions was demon strated by the aid of a second series of simulations assuming that the emis sion interventions were implemented only at local scale. The results of the simulations reveal that ozone exposure in conglomerations as the ones cons idered in this study depends on both urban and regional scale influences. U rban VOC control is found to be effective in reducing ozone primarily on th e local or urban scale, whereas urban NOx control may cause an increase of urban peak ozone while contributing to an effective reduction of regional o zone. (C) 2000 Elsevier Science Ltd. All rights reserved.