Air Pollution Data in London Does Not Support Mayor’s Claims

Yet again the Mayor of London, Sadiq Khan, has used school children to promote his policies to expand the ULEZ in a photo-shoot. He said “In central London, the world-leading Ultra Low Emission Zone has already helped cut toxic roadside nitrogen dioxide pollution by nearly half and led to reductions that are five times greater than the national average”.

But in fact a recently published report by the London Borough of Lewisham shows that air pollution has fallen dramatically in recent years even in outer London boroughs. This is clearly the result of changes to vehicles and in 2020 by Covid lockdowns reducing traffic.

This is what we have said to supporters of our campaign against the Lewisham LTNs:

There is major public concern on the impact of the road closures in the LTN on air pollution because they have diverted traffic onto surrounding roads. Such roads as Burnt Ash Road, Lee High Road, Lee Road, the South Circular and others are residential roads and there are reports of increased air pollution.

A useful report (at least to some extent) has just been published by Lewisham Council. It contains their “Air Quality Annual Status Report for 2020” (available from this page: https://tinyurl.com/pmhsu6up ).

The report contains measurements of nitrogen dioxide (NO2) and particulates (PM2.5) over the last few years up to the end of 2020 from about 50 sites across the borough. An additional 51 sites were added in September 2020, many located within the LTN such as on Manor Lane and Burnt Ash Road, but that was of course after the Lee Green road closures were instituted. It is therefore impossible to see the impact of the road closures as no proper “before and after data” has been collected and the Covid lock-down measures will also have complicated any analysis. The biggest reduction occurred in the last two years but that might be due to reduced traffic volumes.

However the data shows that there have been consistent falls in pollution since 2014 (an average decrease of 38% for the seven year period). The levels reported are now all within the National Air Quality Standards, although some people argue that those standards should be raised.

It is no doubt the case that the falls in air pollution levels that have taken place prior to 2020 and continued in that year have occurred due to cleaner vehicles. Older vehicles have been scrapped and standards for new vehicles have been raised by Government regulation – for example by the move to Euro 6 standards. 

The borough supports the Mayor of London’s commitment to reduce the PM2.5 limit but as the report says “a large percentage of PM2.5 in London comes from regional and other transboundary (non-UK) sources”. It is clear that action on particulates, which is probably more important in health terms than NO2, needs to be taken at a national or international level.  In other words, local LTNs in Lewisham are not going to have a significant impact on background levels of air pollution.

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