ASA Adjudication on Transport For London

Ad

A poster, for Transport for London, was headlined "Less road traffic emissions"; the 'c' in the word "traffic" was replaced with the congestion charge logo. A strapline stated "The Charge is helping it happen".

Issue

The complainant, who believed the Congestion Charging scheme had not helped to reduce road traffic emissions because levels of air pollution had remained broadly the same since its introduction, challenged Transport for London to substantiate their claim.

CAP Code (Edition 11)

Response

Transport for London (TfL) said the complainant seemed to have based his assertions on air pollution data, which, they maintained, was not related directly to the level of road traffic emissions (RTEs). They pointed out that the ad referred only to RTEs and not to the broader issue of air pollution. TfL sent a copy of the Congestion Charging (CC) Impacts monitoring Fourth Annual Report, June 2006. The report included emissions data compiled by the London Air Quality Network, operated by King's College London, and based on established methodologies. They pointed out that the data demonstrated that emissions had decreased because fewer vehicles were moving through the congestion zone more efficiently. More generally, vehicles tended to have better engine efficiencies due to improvements in vehicle technology.

TfL said the indirect relationship between RTEs and air pollution was shown when considering the intervening factors between the point of emission, the exhaust of a vehicle and the point of measurement - the monitoring station. For example, they pointed to other sources of emissions both within London and externally, which contributed to general air pollution. TfL also said the general climatic conditions over a particular period affected significantly the levels of air pollution. For instance, 2002 was, on average, a wet year and that reduced the level of pollutants in the air, compared with 2003, which was hot and dry and resulted in greater air pollution. They pointed out that those variations coincided with the introduction of CC and, as such, masked the beneficial effects of the charge. TfL accepted that several of the components of RTEs had a negative impact on emission levels and therefore increased air pollution. They also accepted that because the charge affected emissions only during week day hours, the effect was limited. They maintained, however, that the overall impact, as demonstrated by the data, was positive and resulted in a net reduction of RTEs.

Assessment

Not upheld

The ASA consulted The Environmental Research Group (ERG) at King's College London who carried out the monitoring and emissions modelling for the London Air Quality Network and provided emissions data to TfL. They said the level of RTEs was directly related to levels of overall air pollution only if all other factors remained constant. They pointed out that air pollution was affected by other determinants, principally meteorology, which tended to mask the effect of changes to the level of any particular source of emissions. They pointed out that the year before the introduction of CC had been a stable meteorological period, which was conducive to better air quality than the following year when CC began to affect RTEs. The ERG considered that the 'masking effect' made it very difficult to draw conclusions about RTEs from air pollution data and agreed with TfL's view that the complainant had confused RTEs with levels of general air pollution. The ERG also said the claim was based on their modelling of the emission's profile following the introduction of CC, which, they pointed out, was based on the established methodology and analytical toolkit used by government agencies and European bodies. The ERG concluded that the claim was consistent with current data.

We noted the distinction between RTE and the factors affecting overall air pollution. We understood the subject was complex, but noted TfL had focused their claim on the reduction in RTEs and made clear in the strapline that CC was "helping" it happen. We also noted the ERG's opinion that TfL had based their claim on a coherent interpretation of the available data. We considered, therefore, that it was reasonable for TfL to make the claim and concluded that the ad was unlikely to mislead.

We investigated the ad under CAP Code clauses 3.1 (Substantiation), 7.1 (Truthfulness), 49.1 and 49.3 (Environmental claims).

Action

No further action required.

Adjudication of the ASA Council (Non-broadcast)