ASA banned Brighton council's 'The cosy killer' ad over an unproven pollution claim

Brighton & Hove City Council ran a campaign to raise awareness of the damaging impact of particulate matter pollution from domestic wood burning.

A digital poster stated that harmful particle pollution near four city primary schools was 78% higher last winter than the summer before, blaming wood burners and open fires with the 'cosy killer' tagline.

The ASA banned the ad: it implied a direct causal link the authority 'had not seen evidence to substantiate', ruling it likely to mislead — while making no ruling against the campaign as a whole or its other materials.

Brighton & Hove City Council's digital poster showed a wood-burning stove emitting smoke in the shape of an adult and child, with the text: 'Harmful particle pollution near four city primary schools was 78% higher last winter compared with last summer. Wood burners and open fires. The cosy killer.'

Two complainants — one of them the owner of a chimney sweeping business — said the ad misleadingly implied wood burners and open fires caused the increase. The Advertising Standards Authority agreed: the ad implied a direct causal link between those heat sources and the claimed rise in particulate pollution nearby, and that they were its sole cause. 'We had not seen evidence to substantiate the claim. We therefore concluded the ad was likely to mislead.'

The ASA banned the ad and told the council to hold robust evidence before stating or implying such causal links. Council cabinet member Tim Rowkins responded that the city has 'clear and detailed local data' on solid-fuel burning's impact on air quality, that only one graphic lacked a sufficiently clear link to evidence, and that there was 'no ruling against the campaign as a whole'.

The 78% statistic was about one winter near four schools, but the stove graphic and 'cosy killer' framing generalized it into a single-cause claim.

The ASA's objection was to the implied causal chain, not the awareness goal — the council's data showed impact, not sole causation.

The ban shows civic campaigns get no exemption: the same substantiation rules apply to a council as to a brand.

The council kept the campaign running, arguing only one graphic was insufficiently linked to the evidence.

Public-health ads carry the same evidential burden as any claim: a true statistic plus a visual villain still misleads if the causal link between them isn't proven.

The ASA told Brighton & Hove City Council to ensure robust evidence backed any future claims of a direct causal link between wood burning and particulate pollution increases. The council, citing well-documented PM 2.5 health impacts, said it would continue working towards cleaner air and defending the rest of the campaign.