This report describes the current regulatory framework and technical evidence on proposed work items. The purpose of this document is to identify knowledge gaps in the subject area of RAPTOR - Research of Aviation PM Technologies, mOdelling and Regulation – and where outcomes from RAPTOR may help fill some of these knowledge gaps. Finally, the report aims to identify and articulate further future research needs in this area and will set out a road map for future work and help establish a co-ordinated action to bring together the regulatory community and associate stakeholders. (This report is a joint deliverable for D3.1, D3.2 and D3.5) RAPTOR contributes to the following areas related to aviation PM emissions: measurement uncertainties and regulation at engine exit plane (WP4); modelling transport, dispersion and transformation of engine emissions (WP5); and health impacts (WP6). WP3 aims to coordinate, communicate and provide a regulatory overview of these technical work packages.