The researchers said the introduction of the Lez helped to reduce particulate matter (PM10) in Greater London by 13% between 2008 and 2013, compared to between 2003 and 2007.
Nitrogen dioxide levels had also fallen by 18.4% in 2019 following the launch of Ulez in central London, compared to the period between 2016 and 2018, according to the analysis.
More evidence that low emissions zones work!
The article partly addresses this.