SG2 in relation to SG4 and other SGs SG2 to prescribe a case or certain case characteristics relevant to the impact of natural sources for SG3 and SG4 to take into account in the preparation the benchmarking infrastructure SG 2 to consider some appropriate metrics to provide to SG4 for the purposes of benchmarking of SA applications Explore the opportunities for SA to help out in the estimation of emission uncertainties (SG3)

SG2 in relation to the GDs and other business Provide a section about NO2 SA to be included in the NO2 guidance document in view of the preparation of time extension reports for NO2 Concrete guidance is desirable, putting emphasis both on methods and issues of QA and uncertainty estimation

SG2 – other business Further explore the options for MDS system update for SA model applications Continue investigating options for synergy with other projects and activities (JRC initiative, MEGAPOLI, PASODOBLE, MACC etc.) SG2 will formally notify participants of SG2 and competent authorities about the JRC initiative on receptor modelling intercomparison Review of current practices for the evaluation of models used for SA to identify limitations and needs regarding assessment of uncertainties.