Towards a European common protocol for receptor modelling

The identification of sources is one of the prerequisites for the implementation of the Air Quality Directive (AQD). It provides scientific support to the development and periodic revision of air quality plans and short term action plans and to the quantification of categories with special status like long range transport, natural sources and winter road salting and sanding. The suitability of receptor models (RM) for the apportionment of pollutant sources in the implementa-tion of the AQD is testified by the amount of published studies in 2005 and 2010 in correspondence with the entry into force of new provisions for PM10 and PM2,5, respectively. In recent years, Member States were requested to provide official estimations of source contribution to the Commission like the quantification of natural sources in 2006 and PM10 time extension reports in 2009 (Fragkou et al., 2011). These experiences have shown that al-though this kind of methodology is used by about 60 % of the European experts involved in source apportion-ment there is a considerable variability in the methodo-logical approaches and adopted tools. Furthermore, there are critical steps that require strict quality assurance standards and skilled practitioners (e.g. identification of the appropriate number of sources). In order to foster harmonization in this field, the JRC has promoted a number of interconnected initiatives linked to FAIRMODE. One of those was to set up a group of experts with skills in different areas to assess RM methodologies and propose common criteria and procedures for source apportionment studies. The infor-mation collected was summarized in a document which is intended to serve as a basis for a common Receptor Model Technical Protocol (RMTP). The RMTP is addressed to different kinds of us-ers: Policy makers and managers interested in the output of RMs for development of mitigation measures, air quality experts and scientists unfamiliar with these tech-niques, and RM practitioners involved in the model ex-ecution and interpretation of results. In order to address such heterogeneous readership the document was designed to be accessible at different levels. The RMTP is organized in three sections : an introduction to present the methodology to the unskilled reader, illustrating its capabilities and recom-mending when and how to use it ; a core section concerning the most common RM methodologies for source apportionment with in-depth analysis boxes for more experienced readers. The section is structured in 13 chapters following, as a check list, the logical steps to accomplish a source apportionment study. The first chapters deal with preliminary activities like the evaluation of the study area, collection of exist-ing information and experimental design. In the follow-ing chapters data collection and data treatment are dis-cussed. The section includes also chapters regarding spe-cific aspects of widely used methodologies like CMB, Factor Analysis, and PMF. The evaluation of test per-formance and reporting are discussed in the last part of this section ; the third section of the document was conceived to give an insight on the capabilities and the possible future trends in RM methodology. It consists of four chapters dealing with advanced, innovative techniques for which ready- to-use tools are already available or under development : trajectory analysis combined with RM, constrained and expanded models, AMS data processing, and the aethalometer model. The document includes a number of annexes to provide additional and practical information on specific topics, and examples.