The practice of releasing balloons in an act of celebration has been banned in some states in the United States because of its environmental impact.

A parent says a school's plan to release balloons to mark the end of the year sets a bad example to children around looking after the environment.

Rural Puketaha School north east of Hamilton will release the balloons at its prize giving on December 13. The post prize giving release is a tradition for students where they write a note to themselves attached to the balloon.

Hamilton parent Tracey Stirling said she was concerned the practice legitimised littering in the eyes of the students.

"It's not cool anymore to release plastic into the environment," she said.

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Stirling's child graduated from the school last year and said concerns were raised then about the tradition and she contacted the school to see if it was being repeated.

She was told by staff that it was, which surprised her.

"What comes up must come down and you're basically taking a piece of plastic, chucking it into the air and letting it go somewhere.

"I understand it's a tradition but when a tradition affects the environment, isn't that a good time to change it? We all know better now and we know that's not the thing to do."

Stirling said the deflated balloons could be eaten by animals or end up in waterways.

In a statement, principal Geoff Booth said the school had not previously received any concerns.

"However, mindful of environmental considerations we made the decision earlier this term to using biodegradable latex balloons and jute string for this celebratory tradition.

However, Stirling said those balloons still took six months to break down.

There have been moves in recent years to stop balloon releases. In 2016, Massey University stopped the practise as part of university students graduation ceremonies because of its threat to wildlife, particularly marine mammals.