South Australia's Department for Transport and Infrastructure has been told to take down bus ads that falsely called natural gas 'clean and green'. These ads, on some Adelaide Metro buses since the early 2000s, claimed compressed natural gas (CNG) was environmentally friendly. The advertising regulator, Ad Standards, ruled the claims misleading after a complaint from Comms Declare, a non-profit. Comms Declare said gas is mainly methane, a strong fossil fuel harmful to the climate. Their complaint said the ads suggested gas was better for the environment, which is false. The Ad Standards panel agreed, saying the ads broke three parts of its environmental code. The panel noted that while CNG buses were once seen as cleaner than diesel, better options like electric, hydrogen, and hybrid buses exist today. Studies show CNG buses emit almost as much greenhouse gas as diesel buses. Adelaide Metro is now switching to electric buses described as "better for the environment". Belinda Noble, Comms Declare’s founder, said the decision warned advertisers against falsely promoting gas. She added, "Methane gas creates toxic pollution at all stages of its production and use and is a major cause of global heating." This comes after similar rulings against Hancock Prospecting and Australian Gas Networks ads. Ad Standards confirmed the Department for Transport will "take the appropriate action to remedy the issue" soon. A department spokesperson said only a "small number" of buses carry the ads. They claimed CNG is a "cleaner burning alternative to diesel" with about 13% lower greenhouse gas emissions and "considerable reduction in harmful emissions" of pollutants like carbon monoxide and nitrous oxide.