The Advertising Standards Association has upheld two out of six complaints made about recent TfL TV, radio and press adverts regarding Ulez.
One of the complaints stated that nitrogen dioxide emissions had come down by almost half since the earlier implementation of the Ulez zone.
However, the ASA said that TfL had not explained how it calculated the reduction, which was based on a modelled scenario rather than real sampling of air quality.
The regulator also found, in a second advert, that the claim “most air pollution-related deaths actually occur in outer London areas” was not substantiated and was again based on a modelled scenario.
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The ASA did not uphold further complaints regarding the statement “London has an urgent air quality problem”, as it found that figures from a Defra report last year showed that Greater London does not meet the legal limit for nitrogen dioxide, which is one of the primary problematic particulates for air pollution.
In a TfL spokesperson told the BBC that the “rulings centred around a minor technical points it some adverts”.
The ASA also upheld a complaint about a GLA advert which made the statement “According to research, one of the most polluted places in London is inside your car” — ruling that it could not be substantiated.
Ulez has long been a controversial topic, causing a huge stir at the Uxbridge byelection, with some motorists objecting to the increased charges for motorists, arguing that it disproportionately impacts small businesses.
Around 95% of cars driving in London are already ULEZ compliant.
