FOI - ULEZ expansion and expected reductions in NO2 and PM2.5 levels [Aug 2023]

Your request

What estimates of the expected reductions in ambient NO2 and PM2.5 levels in outer 
London were used to inform the Mayor’s decision to expand the ULEZ? 

Full reference details and expected reductions in percentage terms or µg/m3
please. Note this question refers to total airborne NO2 and PM2.5 levels, roadside and 
background, not just the reduction in exhaust emissions.

Our response

This information is publicly available.

Following a public consultation that ran from 20 May to 29 July 2022, the Mayor decided to 
expand the ULEZ London-wide from 29 August 2023. 

The evidence base and expected outcomes and impacts of the proposals to expand the ULEZ London-wide were set out in the key consultation documents, available on Transport for London’s consultation page.

The most relevant document is titled ‘Our proposals to help improve air quality tackle the climate emergency and reduce congestion by expanding the ULEZ London-wide and other measures’.

Section 6 of this document sets out the expected impacts of the London-wide ULEZ on 
emissions and concentrations of key pollutants. These are summarised on page 55 and 
described in more detail from page 60. Appendices C and D of this document provide more 
detail on the method used to calculate these estimates and breakdowns of these impacts across different parts of London and on a borough by borough basis.

The Mayor made the decision to expand the ULEZ London-wide after taking into account a 
detailed consultation report and integrated impact assessment. The Mayor has been clear that this was not an easy decision but a necessary one, due to the impact of air pollution on people’s health.

The Mayor’s decision (including the rationale for the decision), the information he considered, and supporting documentation can be found on the GLA website.

If you have any further questions relating to this matter, please contact us, quoting 
reference MGLA230823-4893.