A green group has renewed its call for a Hong Kong-wide ban on idling engines - rather than bans in selected districts - ahead of a consultation next month on whether to draft a law requiring motorists to switch off their engines while waiting. Phil Heung Fu-lap, chairman of Clear the Air's idling engine Committee, urged the government not to consider a limited idling ban. 'Air flows all the time. It will be of no use if the ban is a partial one. If you ban idling engines in Causeway Bay but the ban does not apply in Wan Chai, does it mean Causeway Bay will be able to avoid emission pollutants? Of course not,' Mr Heung said. His views, however, appear to differ from those of Donald Tsang Yam-kuen. In his election platform last week, the chief executive said legislation should require motorists to switch off their engines while waiting. However, he added: 'The prospective legislation may require motorists to switch off vehicle engines at particular hours and in particular zones.' The green group noted that in addition to environmental concerns, a selective ban would cause 'political mayhem'. 'What criteria do you use in picking a district in which to impose a ban and another district in which not to have such a ban? Who will make the final decision?' Mr Heung asked. 'If Causeway Bay has such a ban, but not in Wan Chai, it might cause property prices in Causeway Bay to rise while prices in Wan Chai fall because of the difference in air quality. It will be so unfair.' The group urged the government to imitate countries like Canada, the United States and Britain, where such a ban has been in place for many years. He said that in Canada, drivers must switch off their engines within one minute of stopping. In Central and Sheung Wan yesterday, the group reminded drivers that it was illegal to leave their vehicle without turning off the engine, and that a HK$2,000 fine could be imposed. 'The response was quite good. We told a few drivers parked outside City Hall that they should switch off their engines when not inside. They immediately turned the engines off,' said the group's chairwoman, Annelise Connell. 'The law is already in place that can help our environment, but not many people know that. We even spoke with four police officers and only two of them knew of such a law.'