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Emissions Factors Toolkit


The Emissions Factors Toolkit (EFT) is published by Defra and the Devolved Administrations to assist local authorities in carrying out Review and Assessment of local air quality as part of their duties under the Environmental Act 1995 as amended by the Environment Act 2021.

The EFT allows users to calculate road vehicle pollutant emission rates for NOx, PM10, PM2.5 and CO2 for a specified year, road type, vehicle speed and vehicle fleet composition.

The EFT is updated periodically due to updates to underlying data including vehicle fleet composition and emissions factors. Users are therefore advised to check this page regularly to ensure they are using the most up to date version of the tool for their studies.

Current Version


EFT v12.0.1

Released: December 2023 (XLSB, 4.1MB)

EFT v12.0.1 User Guide

Released: December 2023 (PDF, 2.16MB, 47 pages)


The current version of the EFT is version 12.0.1.

The accompanying EFT User Guide explains in detail the methodology, datasets and assumptions used in the development of the EFT. It consolidates previously available information and guidance on the use of the EFT, and provides information regarding previous versions (changes and updates).

Version 12.0.1 is identical to Version 12.0 except for the following refinement:

  • Change related to NOx and CO2 emissions from hybrid vehicles at speeds greater than 50 km/h

Briefly, the changes between v11.0 and 12.0 are as follows:

  • EFT 12.0 allows users to output emission up to 2050 for all areas: England (not London), London, Northern Ireland, Scotland and Wales.
    • Detailed sources of fleet composition projection are available in the EFT User Guide.
    • Please note that different policy assumptions are assumed in the London base fleet relative to the other non-London Areas. Therefore, the emissions output by the EFT for the London Area will differ to those output for the other non-London Areas, for the same data inputs.
    • Emissions outputs for the years 2031-2050 are provided in support of climate assessments and appraisals only. Where emissions are to be used after 2030 to inform air quality assessments, the appropriate caveats around the limitations of the analysis must be included to accompany the assessment.
  • Use of the COPERT v5.6 NOx and PM speed-based emissions factors, updated from COPERT v5.3, as taken form the European Environmental Agency (EEA) emission calculation tool.
  • Update to the methodology for calculating CO2 exhaust emissions. Details please see EFT User Guide.
  • The emissions factors for PM non-exhaust emissions sources have been updated in line with information published in the EMEP/EEA Emissions Inventory Guidebook 2019.
  • Emissions for Taxis (black cabs) can now be calculated in Areas outside of London.
  • In the Traffic Format Primary Inputs section, ‘Detailed Option 3’ has been modified to allow users to define the proportion of Electric Cars within the fleet. ‘Detailed Option 4’ has been added, which allows users to define the proportion of Petrol/Diesel/Electric LGVs within the fleet. The ‘All Vehicles’ input format replaces the previous ‘Alternative Technologies’, and now allows users to define the proportions of all vehicle types currently supported by the EFT.
  • The previous ‘Euro Compositions’ and ‘Simple Entry Euro Compositions’ Advanced Options, have been replaced by the ‘Bespoke Euro Fleet’ Advanced Option.
  • The Advanced Options ‘Output % Contributions from Euro Classes’ and ‘NOx/PM10/PM2.5 Annual Emissions Euro Split’ have been removed.
  • A new Advanced Option ‘Bespoke Base Fleet’ has been added. This allows Advanced Users to input User Defined Base fleet data, which will be applied across all links entered as input. This user defined Base fleet data can be entered in formats consistent with data provided on the NAEI website and from the TAG Data Book.
  • The ‘Export Outputs’ option no longer requires the user to define a filename. When selected, an output file will be automatically created in the directory where the EFT is saved with the name ‘EFTOutput_date_time.xlsb’.
  • Other improvements to the front-end Graphical User Interface (GUI) of the ‘Input Data’ sheet. This includes removal of tick-boxes for selection of options, and re-grouping of Input/Output options into revised categories (Primary Inputs, Pollutants, Standard Outputs, Additional Outputs and Advanced Options).
  • Improvements to the architecture of the both the excel and VBA sides of the tool. This means the tool is now able to run large datasets more quickly, particularly when utilising advanced options such as the primary fraction of NO2 This streamlining of the tool also means the file size of the tool has reduced by around 40%.


Previous Version


EFT v11.0

Released: November 2021 (XLSB, 5.7MB)

EFT v11.0 User Guide

Released: November 2021 (PDF, 2.7MB, 44 pages)

EFT v10.1

Released: August 2020 (XLSB, 5.9MB)

EFT v10.1 User Guide

Released: August 2020 (PDF, 0.8MB, 41 pages)


Whilst local authorities are advised to use the latest version of the EFT for all future work, in support of ongoing work, the previous version of the EFT has been provided.

For older versions of the EFT please contact the LAQM Helpdesk for further assistance.

LAQM Helpdesk
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