The ASA's first ever Environmental Claims Study is part of a range of initiatives undertaken by the watchdog to prevent consumers from being duped by 'green' claims in advertising, and was prompted by a significant rise in complaints last year on the issue.
The ASA assessed 195 ads across all media and found that just 6% appeared to contravene codes of practice, all in non-broadcast media. Where breaches were identified, those advertisers were contacted and an assurance sought that they would not run the ads again in their current form.
Examples of culprits included a press ad for low fuel-consumption tyres that was deemed unclear and confusing, and a press ad for a hybrid car that referred to "zero emissions" and "emission-free motoring" but later in the ad carried the contradictory copy "near-zero C02 emissions".
The results of the study suggested that there is increased awareness among businesses of the rules governing the use of environmental claims and that better compliance has led to a "considerable fall" in the volume of consumer complaints.
Christopher Graham, director general of the ASA, said: "The compliance survey demonstrates that the ASA is making real progress in ensuring environmental claims do not mislead through exaggeration, ambiguity or omission.
"The ASA will continue to listen to consumers and work closely with advertisers to improve standards in green and ethical claims even further."