The initial expansion of London’s ultra low emissions zone (Ulez) for motor vehicles has brought notable benefits in reducing pollution, a study has found as the mayor prepares for a big extension to its boundaries.
The report by officials at the Greater London authority and Transport for London could help Sadiq Khan counter a political backlash to the imminent further expansion.
The report has been peer-reviewed by Dr Gary Fuller, an expert on urban pollution at Imperial College London. It calculated that since the zone was introduced four years ago, emissions of toxic nitrogen oxides, or NOx, particularly produced by diesel engines, are 23% lower across London as a whole compared with what would be their estimated level if the scheme had not been introduced, and 26% lower within the zone.
Using the same metric, emissions of dangerous fine particulate matter, or PM2.5s, were calculated to be 19% lower than they would have been without the Ulez within its boundaries, and 7% lower across the whole city.
The zone in which drivers of vehicles which fail to meet certain emissions standards must pay a daily fee, now £12.50, was first rolled out for central London in April 2019.
In October 2021 this was expanded by several miles to the edges of the north and south circular roads. At the end of August the Ulez borders are due to be extended again, covering all 32 London boroughs.
A number of Conservative MPs and some councils have objected to the new expansion, arguing that people in outer boroughs rely more heavily on motor vehicles for transport, and that it is unfair to ask those with older, non-Ulez compliant models to pay for an upgrade.
Khan has insisted the health and environmental toll of pollutants and other emissions justifies the action, saying the new report showed it was “vital” to expand the scheme.
The report offers evidence that the Ulez does not appear to, as some critics warned, simply push vehicles to drive around the edge of it, with boundary roads seeing concentrations of nitrogen dioxide, one of two contributors to NOx emissions, fall by between 19% and 27% compared with the projected case without the zone.
The study also includes figures for absolute levels of pollutants over the course of the zone’s existence, but these can be more complex to analyse given external factors such as the impact of Covid, which saw motor traffic levels in inner London and thus emissions reduce sharply for a period.
Additionally, emissions levels had been falling anyway before the Ulez was created, as newer, less-polluting vehicles emerged, meaning not all reductions can be attributed to the policy.
On the impact of the 2021 expansion specifically, the report said that, on average, 74,000 fewer heavily polluting vehicles a day were being driven within the zone, a fall of 60%.
Khan said the evidence of the zone’s effectiveness was “beyond dispute”. He said: “But there’s still more to do. Toxic air is a matter of life and death with around 4,000 deaths in London attributed to air pollution in 2019. It’s also stunting the growth of children’s lungs and causing people to develop life-changing illnesses, such as cancer, lung disease, dementia and asthma.”
Fuller said the evidence he reviewed showed both the initial, central London Ulez and the 2021 expansion had “brought about measurable and sustained improvements to air pollution from traffic”.
He said: “Many people fear that traffic will simply divert around low emission zones, worsening air pollution for those that live on the boundaries. However, data from London’s air pollution measurement network has shown that this has not happened. Instead, nitrogen dioxide alongside the North and South Circular roads has shown a strong improvement.
“Many cities in the UK and around the world are looking to follow London’s lead. I hope that the evidence here will improve the design of similar schemes more widely.”
