Transport for London (TfL) has been ticked off by the Advertising Standards Authority (ASA) after it ruled claims made about reductions in vehicle pollution were misleading.
TfL ran an advert in the Evening Standard from the Mayor of London saying that the introduction of an Ultra Low Emission Zone (ULEZ) in central London "will encourage the use of newer, cleaner vehicles to reduce vehicle pollution by half".
However, Clear Air in London queried the claim, because it understood this was based solely on computer modelled projections of reductions in exhaust emissions only and excluded other major polluting elements.
TfL said that the modelled projections it used to make the claim are a recognised standard approach for assessing the impact of future proposals of that nature.
It added that it believed the projections had been produced "in a robust way" using established methodologies and bespoke modelling of how drivers would respond to the scheme, reports The Drum.
The ASA said that while it accepted there would be "some inherent uncertainty" when attempting to assess the impact of a proposal such as the ULEZ, the claim that vehicle pollution would be reduced by half was likely to be interpreted by consumers as relating to all types of vehicle pollution, unless it was made clear that it related only to certain types.
The ad watchdog added that because the claim related only to NO2 and NOx vehicle emissions, and excluded CO2 emissions for example, it concluded the claim was misleading.
TfL was told to ensure it makes clearer claims in future adverts.