The 1x1km inventory is based on the NAEI’s national totals drawing upon detailed spatial data to derive the geographic extent of the UK’s emissions. Where reported site specific emissions are accessable through legeslative reporting and industrial collaboration we are able to locate emissions as a point source. Road transport emissions from major roads can be mapped on a link by link basis from DETR’s national dataset of annual average daily flows. Emissions from other diaperate sources such as domestic and minor roads are distributed based on surrogate statistics including population and landcover. A detailed description of the NAEI’s current emission mapping methodology may be found in Appendix A3. Information on mapping methodologies are also published on the internet: