A LIE IS halfway round the world before the truth has its boots on, they say. Most people hear only about the press release (copied and pasted by lazy journalists and presented as the news) while the truth is often buried in barely comprehensible documents through which one has to machete one’s way to arrive at proper understanding.
That’s my excuse for taking about a fortnight to tell you that London Mayor Sir Sadiq Khan’s claim that his Ultra Low Emissions Zone (ULEZ) has significantly reduced pollution levels in the outer London boroughs is all smoke and mirrors. Of course, one suspected this was the case but after the great claims made, it was necessary to read through the 220-page report supporting this nonsense to show it amounted to less than a hill of beans.
By page 10, you know you can’t take anything in it too seriously as it’s stated that ‘analysis in this report is primarily undertaken by the Greater London Authority (GLA) and Transport for London (TfL), with extensive support from an international advisory group of independent experts’. So this is primarily an exercise in Khan’s staff marking their own homework. What of the ‘independent experts’? They were selected by the GLA and paid £300 per ‘session’ (there were three sessions), with an estimated 20 hours total time required, including preparation. That’s about £360 for an eight-hour day, a nice little earner.
TfL claim that since ULEZ was introduced in 2019 it has reduced roadside nitrogen dioxide (NO2) levels by 27 per cent across London and by 24 per cent in outer London, and that since the last expansion of ULEZ in August 2023 NO2 levels have fallen by 4.8 per cent in outer London boroughs. The report states that these figures are arrived at by comparing actual NO2 levels with what ‘they would have been without the ULEZ and its expansions’. So here we have our old friend computer modelling claiming to know what the world would have been like if nothing was done. That discredited genius has told us voting Leave would lead to an immediate 18-month recession, and climate change will wipe out those of us who have not already died because we didn’t take our covid jabs and lock ourselves in our homes. We’ve heard it before and it wasn’t convincing or right the first time.
The wording of TfL’s claims itself invites suspicion; why would ‘ULEZ and its expansions’ reduce pollution in outer London so much when only the last expansion of the ULEZ affected vehicles travelling in outer London?
It’s nigh on impossible to review a statistical model without a full working copy of it, to peer into the black box and reveal the mysteries within. But it isn’t usually necessary to get into the technicalities of algorithms to know you’re being had. To justify their conclusions, TfL have to set out some of their assumptions and actual data, and that proves sufficient to undermine their own case. Below is the report’s presentation of recorded NO2 levels since 2014 in different parts of London and outside it.
ULEZ was introduced in central London in 2019, two years after its precursor the Toxicity Charge, and the trend line there suggests that it may have resulted in NO2 reductions, but the downward trend in pollution elsewhere is very similar and has only been interrupted by reduced vehicles journeys during Covid lockdowns. As pollution levels have been falling since 1970, any claim that recent reductions are due to specific local policy changes is going to be difficult to prove. Good luck separating the effects of ULEZ from, say, the introduction of Euro 6 standards for diesel engines in 2015, which reduced permissible nitrogen oxide emissions in new vehicles from 0.18g per kilometre to 0.08g per kilometre.
Only the nerds and bloody-minded (I plead guilty on both counts) will gets as far as page 191 of TfL’s report where there are tables showing monthly NO2 levels since the introduction of ULEZ in outer London, along with figures for the area just outside London. Ignore the crystal ball gazing of what would have happened without ULEZ and look at what has been recorded.
So there you have it: underlying TfL’s estimate that NO2 levels have fallen by 4.8 per cent due to the introduction of ULEZ to outer London is actual data showing that NO2 level fell more rapidly just outside London. TfL try to explain this away by arguing that there are few NO2 monitoring sites outside London so any comparison had a significant degree of uncertainty, which also makes any modelling they have done equally lacking in confidence.
TfL also claim that vehicles emissions of PM2.5 (microscopic dust particles that one would rather not have in the lungs) are estimated to be between 6-32 per cent lower across all boroughs in 2024 than when compared against a ‘No London-wide ULEZ expansion’ scenario. Here, the reductions are greatest in outer London and lowest in the centre, the exact opposite of what is claimed to have happened for NO2 levels. How is that possible? Euro 6 diesel engine emissions for particulates are the same as for Euro 5 (0.005g per kilometre), so how could penalising driving the latter vehicles lead to big decreases in PM2.5 levels?
As I pointed out at the time that the ULEZ expansion was being introduced into outer London, the report TfL commissioned as part of the consultation for that exercise forecast NO2 reductions of only 1%. So why do they now claim that the effect of ULEZ has been so much greater?
So many questions, so few journalists asking them. But until someone comes up with some convincing answers, I’m not buying this ULEZ enthusiasm and neither should you.
