Comparison of EFT v11 and EFT v12: Implications for Air Quality Assessment

On Friday 24^th November, Defra issued a new version of its Emission Factor Toolkit (EFT v12). The EFT is routinely used in air quality assessments across the UK and provides estimates of how emissions from different types of vehicles, in different parts of the country will change in the future. An update to the EFT was long overdue as the previous version (EFT v11) did not account for the potential effect of the COVID-19 Pandemic and the current cost of living crisis on the renewal of the UK vehicle fleet.

This note compares the predicted changes in emissions of nitrogen oxides (NO_X) and particulate matter (PM2.5 and PM10), for the average light duty vehicle (LDV) and the average heavy-duty vehicle (HDV) in urban areas in England and in London, between EFT v11 and EFT v12. Vehicle speeds were set to 50 kph.

The analysis presented herein has immediate implications for local authorities who are reviewing air quality assessments for developments across the UK, as emissions from certain types of development may have been underpredicted and hence present a greater risk to public health.

England (urban)

Central London

Inner London

Outer London

Observations and commentary

In urban areas outside London:

• Emissions of NOx from both LDVs and HDVs were generally underestimated in EFT v11, compared to EFT v12.
• There was signficant underesitmation of NOx emissions from HDVs in EFT v11, which may have implications for air quality assessments for uses with a high proportion of HDVs (e.g. Storage and Distribution).
• Emissions of PM2.5 and PM10 from LDVs were generally underestimated in EFT v11.

In urban areas in London:

• There is generally good agreement in predicted emissions of NOx from LDVs in Central, Inner and Outer London between 2018 and 2021, and underestimation of NOx emissions from 2021 onwards in EFT v11 (the ULEZ was expanded in late 2021).
• PM10 emissions from HDV were generally overestimated in EFT v11.
• PM10 emissions from LDV were generally underestimated in EFT v11.