Defra and the Devolved Administrations provide mapped background air pollution concentration data and an Emissions Factors Toolkit (EFT) to local authorities to support air quality assessment. The current version of the background maps use a 2010 base year and the current version of the EFT is v5.2.
As far as possible Defra and the DAs seek to ensure the data and tools are supported by the best available evidence on emissions and concentrations of air pollution. In recent years there have been ongoing research questions regarding discrepancies in trends of NOx emissions and concentrations, the real-world performance of diesel cars and LGVs and the future emissions from Euro 6/VI vehicles. Defra is in close contact with the Department for Transport and experts across the EU to benefit from the latest understanding and information.
Defra is currently undertaking a review of the underlying assumptions so it can update the information and tools made available to local authorities. It is expected that a new version of the background maps and EFT will be issued in early 2014.
The Scottish Government publishes separate background maps for Scotland and will await the outcomes of this review before issuing updated versions.