Emissions down and compliance up since ULEZ extended to outer London, says GLA

Nitogen oxide (NOX) emissions from cars and vans in outer London have fallen by 13% and 7% respectively since the Ultra Low Emission Zone (ULEZ) was extended across the capital. Meanwhile, PM2.5 particulate emissions from cars and vans in outer London were 20% lower than they would have been had ULEZ not been expanded. These are among the findings in a new report from the Greater London Authority (GLA) assessing the first six months of the extended ULEZ.

“This Six Month Report shows a reduction in PM2.5 concentrations, which is bringing important health benefits to Londoners,” says GLA. “PM2.5 reductions are associated with reduced acute respiratory and cardiovascular hospital admissions, incidence of heart disease and stroke and reduced levels of all-cause mortality.”

NOX emissions from cars and vans are 11%, and 6% lower, respectively, than would have been expected without the ULEZ expansion, the GLA estimates. This equates to a total NOX emissions saving of 456 tonnes London-wide.

In the first six months of operation, roadside nitrogen dioxide (NO2) concentrations in outer London were up to 4.4% lower than would have been expected without the London-wide ULEZ expansion, states the GLA.

Roadside NO2 concentrations are estimated to be 21% lower in outer London than they would have been and 53% lower in central London than they would have been without ULEZ and its expansions.

NO2 was 24% per cent lower in inner London than it would have been without ULEZ and its expansions, according to GLA data.

The expansion of ULEZ across all London boroughs in August 2023 has disincentivised the use of older, more polluting vehicles within the city through applying a daily charge to vehicles that do not meet certain emissions criteria, says the GLA report.

“Long term trends indicate that average concentrations in all London zones improved at a faster rate than the rest of England average over the same time period. This is particularly notable in outer London where concentrations have improved more rapidly over recent years and are now similar to the rest of England average, which has historically been lower.”

Areas outside the capital are also seeing the impacts of the ULEZ, with roadside NO2 concentrations within 5km of the Greater London boundary on average 9% lower in 2023 than a ‘No ULEZ’ scenario, the report suggests. “As this is an average for the whole boundary zone, this means that some roads will be seeing even greater reductions.”

Compliance within the extended ULEZ is rising, GLA notes, stating that ULEZ vehicle compliance is now 96%, up from 90.9% in June 2023. This is nearly the same level of compliance as seen in inner and central London, with 96.5% and 96% respectively.

Compliance rates have increased for both cars and vans; 97.1% of cars and 88.9% of vans seen driving in the extended ULEZ met the standards after six months of operation, up from 93% and 80.2% in June 2023 and 44% and 12% in February 2017.

On an average day, there were 90,000 fewer non-compliant vehicles detected in the London-wide ULEZ in February 2024 compared with June 2023, analysis shows.

The biggest impacts on emissions from cars and vans have occurred in the outer London zone as a result of the London-wide expansion of the ULEZ, says GLA.

“This equates to a saving of 424 tonnes of NOX in outer London in 2023 and the NOX emissions savings in outer London represent over 90% of the total emission reductions seen in London as a result of the London-wide expansion.”

GLA says that a fuller analysis of both emissions and concentrations within ULEZ will be reported in the One Year Report. “However, this initial analysis indicates that the London-wide ULEZ expansion has had a positive impact on air quality in London.”

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