Recently 'Chinese' lanterns or sky lanterns have become popular at birthdays, weddings and other celebrations. Although we cannot state that you should not use them, they do pose risks. Some issues are:
The paper can degrade in about six to eight weeks. But the wire in them can last nine months and is of a fine gauge with sharp ends. There are some without wire that use cane, wool or string – but these still take time to degrade and could cause issues for livestock and littering.
There is evidence that their use has caused moorland or forest fires at certain times of year when vegetation and weather conditions have made sites vulnerable to fire.
There have been examples of cattle and sheep eating the lanterns and wire. This has caused injury to stomachs and mouths. There are recorded cases in the UK of death from internal injury.
Farmers cutting grass for stock feed or bedding can gather wire and other lantern parts in the grass, which in turn is fed or used as bedding for stock.
Even though some parts are biodegradable they do remain on view either on the ground, in trees and hedges, which is an eyesore.
The UK Coastguard has been called out on false alarms when lanterns have been confused with distress flares.
All the suppliers have disclaimer that they have no responsibility for accidents or injury caused and that releasers of lanterns could be liable.
These safety instructions are provided for guidance and are not exclusive. It is entirely the responsibility of the persons lighting and launching a sky lantern to take due care.