he expansion of the ultra-low emission zone to the edge of the North and South Circular roads resulted in an astonishing 60 per cent reduction in the number of non-compliant vehicles being driven in inner London.
This included a 63 per cent reduction in the number of “dirty” diesel cars – those which break the Ulez rules and would have to pay the £12.50-a-day levy.
Their number reduced from 79,000 to 29,000 a day in the 12 months after the Ulez was expanded to the suburbs in October 2021.
A report by Transport for London, analysing the impact of the first year of the Ulez expansion, said the “significant” fall in the dirtiest diesels was a “key metric of success for the policy in removing harmful emissions from the city”.
But the 96-page report also revealed that levels of nitrogen dioxide (NO2) in central London – the same area as the congestion charge zone, covering the West End and City of London financial district – had risen since the Ulez was expanded.
The Ulez was credited with reducing NO2 levels in central London by 56 per cent in central London and 22 per cent in inner London between October and December 2021.
But by October last year, this had fallen to 46 per cent and 21 per cent – a finding likely to be seized upon by opponents of expanding the Ulez for a second time to the Greater London boundary.
The report said: “Central London roadside concentrations have risen slightly since the end of the pandemic as traffic returns to central London. As the concentrations have risen the Ulez impact has therefore reduced.”
But it said NO2 remained below pre-pandemic levels – showing the Ulez’s “sustained and positive impacts on pollution” by encouraging drivers to switch to cleaner vehicles.
The Ulez expansion to the inner boundaries of the North and South Circulars increased the zone’s size by 18 times and means it now covers four million Londoners.
Mayor Sadiq Khan has decided to extend the zone across all 33 boroughs on August 29, which he says will deliver cleaner air for five million more Londoners.
The first-year report said 94.4 per cent of vehicles driving within the current zone complied with the rules and did not have to pay the levy.
Prior to the zone’s widening, only 86.9 per cent of vehicles met the exhaust emission standards.
The total number of vehicles seen within the zone on an average day has fallen by 4.9 per cent, from 950,000 to 903,000.
Of these, the number of non-compliant vehicles has reduced from 124,000 to 50,000 – a drop of 74,000, or 59.7 per cent.
But this means TfL is raising less cash – about £400,000 a day. More than a quarter of non-compliant vehicles are exempt from paying the levy or the £180 penalty fines.
The Ulez has encouraged motorists to switch to cleaner vehicles – there has been a 3.1 per cent increase in compliant vehicles, up from 826,000 to 852,000.
Mr Khan said: “The evidence from this landmark report is clear – the Ulez works. This is beyond dispute.
“With the majority of deaths attributable to air pollution in outer London, it’s vital that we expand the Ulez London-wide.”
But Nick Rogers, City Hall Conservatives transport spokesperson, said: “Sadiq Khan’s Ulez expansion will have a negligible effect on air quality in outer London, while hitting low income and vulnerable families hardest.
“Sadiq Khan needs to listen to Londoners, scrap his expansion, and spend the money on policies that actually reduce air pollution.”
The report also reveals the biggest cut in emissions has been seen in the bus fleet – which is not subject to the Ulez rules.
There has been a 75 per cent reduction in NO2 emissions from London buses since 2019, following the retro-fitting of cleaner engines and replacement of old vehicles with electric buses.