The regulation is so obscure that funeral directors who organise ceremonies where balloons are released in memory of the deceased said they weren't even aware of it. The law lies quietly on the books and the balloons rise quietly into the air.

But it's now coming into closer focus because the Greens party is pressing the ACT government. The Greens said it supported the regulation and wanted to know if people had been punished. It has also taken steps to ban balloons from its own campaigning events.

And they called on the other parties to match its efforts. “The ACT Greens challenge the ACT Labor and Liberal parties to stop using balloons in their political campaigning, as the ACT Greens have done," ACT Greens MLA Caroline Le Couteur said.

The answer to the Greens' query on the law is that nobody has ever been punished in the ACT. The maximum fine for breaching Environmental Protection Regulation 2005, division 2.6 clause 16 is $1600 for an individual and $8100 for a corporation, but the government said, "no enforcement has been required".

But, all the same, anti-balloon feeling has had an effect on businesses in the ACT. Sellers of balloons are very aware of the law and have bowed to it, but say business has suffered.

Specialist balloon companies have decided not to supply balloons for release into the air - only if they are to be used indoors or tied to the ground.

Adele Craven of Debonair Balloons in Tuggeranong said, "We don't condone the release of any balloons."

She said balloons were for adding the wow factor to parties but not for sending into the air. At funerals, she suggested releasing butterflies.

Another Canberra balloon seller, Kate Reeves of Balloon Brilliance, agreed but she added she thought the fuss had been overblown. The science showed that plastic bags and cigarette butts were far more of a problem for sea animals. Balloons were rubber and not plastic, but were still being caught up in the general anti-plastic movement. They were bio-degradable, she said.

But environmental activists have been raising the pressure since a campaigning film was released last year. Rubber Jellyfish was made by Carly Wilson who once worked for the RSPCA Wildlife Clinic in Canberra. It featured turtles which had eaten balloons having mistaken them for their natural prey, jellyfish.

Balloon sellers said their trade had been hit by the anti-balloon sentiment. They have formed a trade association, The Pro Environment Balloon Alliance, and its director, Chris Adamo, said mourners sometimes wanted balloons at funerals but they had to be told it couldn't happen. "I've told grieving families to their face," he said.

One Canberra balloon seller said she had seen traders called "turtle killers" on Facebook.

But in the funeral business, there was widespread ignorance of the block on balloons. Peter Dinn of Toscan Dinn Funerals said, "We weren't aware that there was a ban."

Judy Cole, director of William Cole Funerals, said she only learnt of it when she asked a supplier for balloons to be told the sale wasn't possible. "I was shocked," she said.

But funeral directors can't stop families from bringing their own and that's what happens occasionally, particularly at children's funerals.

"It's a family's choice," she said.

At weddings, balloons are not in fashion, according to Darren Roberts, a marriage celebrant in Canberra. "It is generally flowers and blowing bubbles," he said.