Environment officials opted to introduce voluntary guidelines rather than laws to combat light pollution, saying enforcement would be difficult and unsuitable.
According to a paper on light pollution submitted to the legislature yesterday, the guidelines would recommend switching off outdoor displays after 11pm and avoiding or minimising flashing lights. A task force might give further guidance next year.
Friends of the Earth, which pushed for legislative control, condemned the government's move.
Hahn Chu Hon-keung, the group's environmental affairs manager, said officials were shrugging off their responsibility.
'It is irresponsible for them to delay as much as they can by introducing voluntary guidelines that, for sure, will not be abided by,' he said.
However, a spokeswoman for the Environmental Protection Department said officials had not ruled out statutory control on external lighting, even though no consultant studies commissioned by the department recommended it.
'Transplanting overseas legislation on light pollution might not be suitable to unique local circumstances,' she said.
The guidelines would cover areas such as operating hours of external lighting, automatic controls, lighting designs, glare affecting pedestrians, light-control measures, and energy efficiency. The department will consult the public for three months on the guidelines.
A task force on external lighting will be set up this year to examine technical standards and advise on ways to tackle lighting nuisances and energy wastage. The government will take the lead by switching off all its commercial outdoor lighting after 11pm, after the existing contract period expires.
Apart from the difficulties of defining light pollution and related nuisances, the department spokeswoman said high building density and mixed commercial and residential uses made it hard to regulate.
She added that high ambient brightness in Hong Kong created a disincentive for advertisers to dim their lights.
'Our ambient brightness level is already high and people erecting signboards might fear their installation is too dim to stand out,' she said.
Another thorny issue with legislation was enforcement, especially when light pollution came from multiple sources. 'It would be difficult to pinpoint who and to what extent they should be responsible,' she said.
Last year, there were 226 complaints on light pollution. A luxury property owner at The Masterpiece in Tsim Sha Tsui also threatened to take legal action to force lights to be dimmed on the roof of The One shopping mall.
The latest policy on light pollution is the result of a series of consultant studies commissioned by the government to address mounting complaints. The studies found light pollution was a localised problem and more acute in busy shopping districts such as Mong Kok and Causeway Bay.