Local councils are being urged to ban releases of balloons and sky lanterns on their land after balloon litter on beaches rose by more than half in a year.
Volunteers taking apart in the Marine Conservation Society's annual Great British Beach Clean last September found litter such as latex or foil balloons and strings was up 53% from 2015 to 2016.
On beaches and in the sea, balloons, strings, lanterns and frames can have long-lasting effects on wildlife, choking or entangling creatures with harmful or even fatal consequences at the coasts and in the water.
The Marine Conservation Society (MCS) is asking the public to pledge their support for a ban by their local authority on balloon releases on council land, such as parks, sports facilities and schools.
The charity is taking its Don't Let Go campaign to a local level to persuade more councils to ban the release of both balloons and sky lanterns on their land, as part of efforts to see all intentional balloon releases stopped.
More than 50 UK local authorities, from Shetland to Cardiff and Cornwall, have already agreed to implement a ban on balloon and lantern releases.
Emma Cunningham, MCS pollution campaigns officer, said: "There's an awful lot of confusion over balloons, especially what they're made of and how they break down.
"Some people believe that because latex is natural, balloons made of it are harmless once let go. This just isn't the case.
"Latex may last for up to four years in the marine environment.
"The latest research also shows that only around 13% of balloons burst into small pieces whilst more than 80% come down intact.
"This could explain the rise in balloon litter levels we have seen on beaches, which will have a great impact on wildlife."
Sky lanterns also pose a threat to wildlife and livestock, and can be a fire hazard to crops or property, the MCS said.
Helium, the gas used to make balloons rise, is running out and should be conserved, the charity added.
Balloon or lantern bans are already in place around the world including some US states and parts of Australia, Germany, Vietnam and Spain.
:: The Marine Conservation Society is urging people to sign up to their online pledge page at http://bit.ly/2nvf8GE and help the charity create an interactive map to show support for bans around the UK.
Local Government Association environment spokesman Councillor Martin Tett said: "The potential for sky lanterns to endanger people's safety, their property and their livelihoods is considerable, and it is understandable why so many councils and other organisations have already banned their use as far as they are able.
"People should also be mindful of the potential impact on wildlife and litter from normal balloons.
"Councils, who have experienced substantial budget reductions, spend many millions every year tackling litter."