Government suggestions to control light pollution, contained in six pages of voluntary guidelines issued yesterday, have been criticised as weak and ineffective.
The measures are aimed at commercial operators' external lighting.
The Environment Bureau's advice includes switching off lights after business hours, installing timer switches and choosing energy- saving devices.
'These guidelines are too broad-brush and some are just common sense,' said Edwin Lau Che-fun, a member of an external lighting task force set up last year and a director of Friends of the Earth HK.
The task force is creating technical standards for possible regulation of external lighting.
These would be considered only after a three-year trial of the guidelines, the bureau said.
The task force had proposed dividing the city into three zones - rural, residential and mixed - to which different standards would apply, Lau said.
Most on the task force also agree that lighting should be dimmed or switched off from 11pm to 7am, but these suggestions are not in the guidelines.