Effectiveness of London’s Ultra Low Emission Zone in Reducing Air Pollution: A Pre- and Post-Comparison of NO2 and PM10 Levels


Air pollution has a detrimental effect on public health. Several policies have been proposed in European cities to tackle emissions, including transport policies. The Ultra Low Emission Zone (ULEZ) was introduced in April 2019 and is an area in London where a fee is charged for polluting vehicles that drive through that area. Our study examined the effects of the ULEZ on local NO2 and PM10 levels. Using secondary data recorded at 16 permanent monitoring stations by continuous ambient air monitoring systems and gathered by London Air, we conducted descriptive analyses of historical trends and inferential pre- and post-comparisons of seasonal levels of emissions. Results show statistically significant reductions of NO2 levels in every site between spring 2018 and spring 2019, while reductions of PM10 levels reached statistical significance in 3 out of 5 sites. Control sites outside the ULEZ did not show statistically significant reductions of NO2 and PM10. Findings indicate that the ULEZ contributed to a decrease of air pollution and is an effective policy for reducing air pollution, which can also lead to public health benefits. Emission levels remain, however, above European Union legal limits in specific instances and thus further action is needed. Additional research is required to assess these changes in the long term.


Speaker / Author: 
Hannen Fredrick John Bishop, Centre for Public Health and Wellbeing, University of the West of England
Anna Bornioli, MA, PhD, Erasmus Centre for Urban, Port, and Transport Economics, Erasmus University Rotterdam
Month Year: 
July 2022
Page #: 
Publication Month: 
July/August 2022
EH Topics: