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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 v11.0

Released: November 2021 (XLSB, 5.7MB)

EFT v11.0 User Guide

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


The current version of the EFT is version 11.0.

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).

Briefly, the changes between v10.1 and 11.0 are as follows:

  • EFT 11.0 allows users to define Input Years up to 2050.
    • 2031-2050 outputs are limited to England (not London) only.
    • 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.
  • Updated fleet splits for England (not London) to extend the fleet data for Motorway, Urban and Rural road types out to 2050;
  • Engine efficiency adjustment factors have been provided by DfT/NH and applied to exhaust CO2 emission outputs up to 2050; and
  • Engine efficiency adjustment factors have been provided by DfT/NH and applied to exhaust CO2 emission outputs up to 2050; and
  • When CO2 pollutant output is selected, an additional output is now provided. The ‘Output CO2 Summary’ sheet provides a summary of direct CO2 emissions from tailpipe and indirect CO2e emissions associated with the charging of the batteries of electric and plug-in hybrid cars and LGVs, in tonnes/annum. N.B. link length is now a mandatory input requirement when outputting CO2 emissions.


Please Note: The default fleet projections in EFT v11.0 are based on fleet growth assumptions which were current before the Covid-19 outbreak in the UK. In consequence, default fleet outputs from the tool do not reflect short or longer term impacts on emissions in 2020 and beyond resulting from behavioural change during the national or local lockdowns.

Previous Version


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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