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ASA Ruling on Transport For London

Transport For London t/a Mayor of London

42-50 Victoria Street


8 April 2015


Regional press



Number of complaints:


Complaint Ref:



Summary of Council decision:

Three issues were investigated, of which one was Upheld and two were Not upheld.


A regional press ad in the Evening Standard, from the Mayor of London, for a proposed Ultra Low Emission Zone (ULEZ) in central London. Text stated, " ... To improve Londoners' health and quality of life, we are proposing an Ultra Low Emission Zone which will operate 24 hours a day, 7 days a week in central London. All cars, motorcycles, vans, minibuses and heavy vehicles will need to meet the new emission standards or pay an additional daily charge to travel within the zone. Taxis and private hire vehicles will also need to meet new emission standards and buses will need to be hybrid or zero emission when driving. Introducing the zone in 2020 will encourage the use of newer, cleaner vehicles to reduce vehicle pollution by half ...".


Clean Air in London challenged whether the following claims were misleading and could be substantiated:

1. the claim that taxis would need to meet new emission standards, because they understood that the standards would only apply to newly licensed taxis;

2. the claim "buses will need to be hybrid or zero emission when driving", because they understood that around 10% of buses would be exempt; and

3. the claim "Introducing the zone in 2020 will encourage the use of newer, cleaner vehicles to reduce vehicle pollution by half", because they understood that this was based solely on computer modelled projections of reductions in exhaust emissions only and excluded other major polluting elements.

CAP Code (Edition 12)


1. Transport For London t/a Mayor of London (TfL) said the aim of the ad was to enable owners of vehicles affected by the proposals to understand that they may be affected and to encourage them to view the detailed information on the TfL website. They said, because the consultation proposals were very detailed, the ad focused on the salient points of the proposals, but did not explain in detail the different emissions requirements for each vehicle category, because that information was published in detail on their website and in their leaflet.

TfL maintained that all vehicle types referenced in the ad would need to meet new emissions standards. They said that, as part of the proposal, all taxis would need to meet the emissions standards based on whether they were newly licensed from January 2018 or were licensed prior to that date. They said if they were newly licensed, they would need to be zero-emission capable, but that if they were licensed before January 2018, they would need to comply with a reduced age limit, going from 15 years old to ten years old from 2020.

They said that vehicle emissions had reduced with each new Euro emissions standard introduced by the European Union (EU). The standards set limits for maximum emissions of air pollutants for new vehicles sold within EU member states. They provided data which showed the stricter emission standards for Euro Standards 1 to 6, which had come into effect between 1996 and 2015. They said that not introducing the reduced age limit would have meant the emissions savings would have been far smaller, which they said demonstrated that the age limit policy constituted a new emissions standard.

They said as part of the consultation they wrote to every taxi and private hire driver licensed in London to explain the proposal in detail. They said the ULEZ proposal had been tailored to reflect the different vehicle types used as taxis and private hire vehicles, their contribution to emissions in the proposed ULEZ and the likely development of the vehicle market for each sector.

2. TfL said that the ad did not claim that all buses would be affected by the same standards. They said all of their double decker buses would be required to be hybrid and single decker buses would be required to be zero emission when driving. They said existing 'New Routemaster' buses were 'Euro V' emission standard and newer ones would be 'Euro VI'.

They understood the 10% of buses referred to by the complainant related to the New Routemasters. They said approximately 300 New Routemasters, which were already hybrid and had emissions standards closer to Euro VI than other Euro V buses, would continue to operate in the ULEZ, without modification, at 2020.

3. TfL said that, when assessing the likely impact of future schemes, they used modelled projections, given that monitoring data of actual pollution levels was only available for present and past years. They said that that was a recognised standard approach for assessing the impact of future proposals of that type. They believed the projections had been produced in a robust way using established modelling methodologies and bespoke modelling of how drivers would respond to the scheme. They said the work was undertaken by King's College London, who they said were the leading providers of air quality expertise in the UK. They said robust estimates of traffic change were incorporated into a recognised air quality assessment framework, and that the modelling took account of the pollutants that were considered harmful to human health and the environment. They said that information on the technique used to model projections was published on their website.

They said the UK Air Quality Standards Regulations 2000 set standards for a variety of pollutants that were considered harmful to human health and the environment, and that the majority of those pollutants were now, within London, at levels which did not affect human health. However, the pollutant nitrogen dioxide (NO2) was well above the European limit in London, and was subsequently their primary focus.

They said the level of NO2 and nitrogen oxide (NOx) vehicle emissions in central London were projected to reduce by 50% and 51% respectively as a result of the ULEZ proposal, which in turn would lead to a reduction in NO2 concentrations. They said there was a complex 'atmospheric chemistry' relationship between emissions of NO2 /NOx and NO2 concentrations.

They said the Supplementary Information (which was available on their website) also provided more data on the estimated change in particulate matter (PM10 and PM2.5) because that was another pollutant of concern. However, for the purposes of the press ad, they felt it was acceptable to avoid technical jargon and instead use the term 'vehicle pollution'. They provided an extract of the information contained in their Supplementary Information showing the impact of the ULEZ proposal on exhaust emissions and pollutants.


1. Not upheld

The ASA understood that 'taxis' referred to 'black cabs' licensed by TfL, which were distinguished from Private Hire Vehicles (PHVs) in the proposals. Although taxis which were newly licensed from 1 January 2018 would have to be zero emission capable, those taxis which were not newly licensed would not have to meet new standards relating specifically to their emissions. Instead, they would have to comply with a reduced maximum age limit when the zone was introduced in 2020.

We understood that, under current rules, in 2020 taxis would be able to have been manufactured as early as 2005, which would mean that they would be subject to the Euro 3 standard of emissions. However, if the zone was introduced, in 2020 taxis would only be able to have been manufactured as early as 2010, which would mean they would be subject to the stricter Euro 4 emissions standard. There were also Euro 5 standards introduced in 2012, and Euro 6 standards, which would come into effect in 2015, which would further affect the maximum emissions of taxis in subsequent years.

We considered that, because taxis were subject to Euro emissions standards based on the year they were manufactured, the introduction of the reduced age limit would mean that taxis would, in effect, have to meet new emissions standards, and therefore concluded that the claim was not misleading.

On that point, we investigated the ad under CAP Code (Edition 12) rules 3.1 and 3.3 (Misleading advertising), 3.7 (Substantiation), and 11.1 (Environmental claims), but did not find it in breach.

2. Not upheld

We noted that the ad separated the claims relating to taxis, PHVs and buses from those relating to other vehicles, which we considered gave the impression that there was a difference in how the ULEZ would apply to different categories of vehicle. The ad clarified that buses would need to be hybrid or zero emission when driving.

We understood that the ULEZ would include proposed new exhaust emission standards (ULEZ Standards) which were based on European standards that defined the limits for exhaust emissions in EU member states. Euro VI standards were the most recent standards, and were stricter than Euro V standards.

We understood that 300 New Routemasters and 400 non-New Routemasters, all 700 of which were 'Euro V' buses, made up the 10% of buses to which the complainant referred. We also understood that all 700 were hybrid buses. We noted that the ad did not include any reference to the specific standards which the ULEZ would require, and we also noted that it was made clear on TfL's website that they would seek to retrofit the 400 non-New Routemasters to make sure they reached Euro VI standards by 2020. The website also made clear that the 300 New Routemasters would not meet the standards required by the ULEZ, but would not be modified because they were much closer to Euro VI standards than other Euro V buses.

We noted that consumers who wished to seek further information could find further, qualifying details online, which would make clear the exact standards required. We considered that it was sufficient for that supporting information to appear on TfL's website.

Because we considered that consumers would understand from the ad that buses in the zone would have to be hybrid or zero emission, and because that was the case, we concluded that the claim was unlikely to mislead.

On that point, we investigated the ad under CAP Code (Edition 12) rules 3.1 and 3.3 (Misleading advertising), 3.7 (Substantiation), and 11.1 (Environmental claims), but did not find it in breach.

3. Upheld

We acknowledged that, when attempting to assess the impact of a proposal such as the ULEZ, there would be some inherent uncertainty, and that modelling was likely to be seen as an acceptable way of predicting the likely outcome. We considered that consumers would be aware that the predicted reduction of "half" would not be able to be demonstrated beyond doubt, and were likely to interpret the claim as a prediction, although we would expect to see relevant support for that outcome from the modelling. We also acknowledged TfL's intention to avoid technical jargon so the claim would be more easily understood.

Nevertheless, we considered that 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. We considered, for example, that consumers would expect carbon dioxide (CO2) to be included in the figure.

We noted that the reduction in pollution figures related to reductions within the zone only. We understood that CO2 was predicted by TfL to be reduced by 15% in the zone, and that reducing CO2 emissions from road transport was one of the stated objectives of the ULEZ. TfL provided figures showing the predicted reduction in PM10 and PM2.5 exhaust emissions as 64%. However, we understood that exhaust emissions were only a part of the overall PM10 and PM2.5 emissions, and that the figures given in TfL's supplementary information for total road transport emissions in central London had been 14% for PM10 and 21% for PM2.5.

Because the claim related only to NO2 and NOx vehicle emissions, and excluded, for example, the figures for CO2, and total PM10 and PM2.5 emissions, we concluded that the claim was misleading.

On that point, the ad breached CAP Code (Edition 12) rules 3.1 and 3.3 (Misleading advertising), 3.7 (Substantiation), and 11.1 (Environmental claims).


We told Transport For London to ensure that they made clear in future that claims about reductions in vehicle pollution referred to specific types of pollution rather than vehicle pollution as a whole.

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