London’s Ultra Low Emission Zone (ULEZ) policy – described as “the world’s most stringent” – has resulted in only small improvements in air quality, new research has found.
ULEZ was introduced by London Mayor Sadiq Khan in 2019 and expanded in October this year, drivers charge £ 12.50 a day if they traveled in vehicles that did not meet specific emission standards – but its efficiency is now being called into question.
Similar policies have been introduced in other British cities, including Bath, Birmingham and Glasgow, where several others have plans to implement clear air zones, and the new research may affect how these policies are developed.
A scientific study of the impact of London’s ULEZ has found that it is marginal, according to scientists at Imperial College London (ICL), but other policies mean that air quality in the city has nevertheless been significantly improved.
Between 2016 and 2020, the number of people living in London living in areas with illegally high levels of nitrogen dioxide fell by 94% as policies such as Low Emission Zone, Low Emission Bus Zones and bus and taxi electrification came into force.
Air pollution causes thousands of deaths a year in the UK due to conditions such as stroke, heart disease, lung cancer and both acute and chronic respiratory diseases, of which an estimated 40,000 occurred in 2019 – of which 4,000 were in Greater London.
Compared to the overall decrease in air pollution in the capital, ULEZ achieved only very small improvements in air quality according to the Imperial College London study.
The researchers found that this resulted in an average reduction of less than 3% for nitrogen dioxide concentrations and negligible effects on ozone and particulate matter concentrations (PM2.5).
The biggest pollution changes all took place before ULEZ came into force.
Dr. Marc Stettler of the ICL said: “Our research suggests that a ULEZ in itself is not an effective strategy to improve air quality.
“The case of London shows us that it works best when combined with a broader set of policies that reduce emissions across sectors such as retrofitting buses and taxis, supporting active and public transport and other taxes on polluting vehicles.”
He continued: “Cities considering air pollution policies should not expect ULEZs to solve the problem alone, as they contribute only marginally to cleaner air. This is especially true for pollutants that can come from elsewhere and be blown into the city of winds, such as particles of matter and ozone. “