Proceedings of the 10 th Int. Conf. on Harmonisation within Atmospheric Dispersion Modelling for Regulatory Purposes Page 649 MODEL BASED YEARLY AIR QUALITY EVALUATION ON PIEMONTE REGION Camillo Silibello 1 , Giuseppe Calori 1 , Giorgio Arduino 2 , Carla Contardi 2 and Franca Sordi 2 1 ARIANET s.r.l., Milano, Italy 2 Regione Piemonte – Direzione Tutela e Risanamento Ambientale, Torino, Italy INTRODUCTION The Environment Council (EC) has been introduced a series of Directives to control levels of certain pollutants and to monitor their concentrations in the air: the Framework Directive 96/62/EC on ambient air quality assessment and management and its daughter directives, which set the numerical limit values, or in the case of ozone, target values for each of the identified pollutants in ambient air. The Framework Directive and the first Daughter Directive (1999/30/EC, setting limit values for NOx, SO 2 , Pb and PM10) introduce, for the first time in European air quality directives, the combined use of monitoring data, emission inventories and modelling techniques in assessment and management of air quality. The availability of a detailed regional inventory covering anthropogenic and natural sources at the detail of individual municipalities, main road axes and relevant point sources (INEMAR 12 ) and of an adequate air monitoring network 13 has induced the Regional Authorities (Regione Piemonte and ARPA Piemonte) to implement, in cooperation with ARIANET s.r.l., a multi pollutant eulerian Atmospheric Modeling System (AMS) to support the air quality assessment and management (e.g.: production of spatial distribution maps, assessment of the contributions of various sources and source categories to exceedences of limit values from; evaluation of the effectiveness of emission control strategies on air quality levels). A similar system is also implemented and applied in the MINNI project (Integrated National Model in support to the International Negotiation on air pollution, Zanini et al. 2004) to provide to the RAINS-Italy Integrated Assessment Model the necessary atmospheric transfer matrices. In this context the AMS has been applied for the 1999 reference year to the Italian domain at an horizontal resolution of 20 km. Emissions, meteorology and pollutant (primary and secondary) concentrations hourly fields produced within the MINNI project may be used to perform nested simulations over the Piemonte region for the year 1999 (Figure 1). In the next sections a description of the AMS and the procedure adopted to perform the regional simulation from the national one are given and the main results obtained in this study are discussed. 12 http://extranet.regione.piemonte.it/ambiente/aria/ 13 http://www.sistemapiemonte.it/ambiente/srqa/ Fig. 1; Nesting from MINNI fields to Piemonte region.