Just as with cutting the use of plastic shopping bags and banning vehicles from parking with their engines idling, introducing energy-saving light bulbs should be a no-brainer. They cost more, but are more efficient, last longer, lead to lower electricity bills and, most importantly, reduce pollution. The government has launched a campaign to phase out Hong Kong's estimated 6.8 million old-fashioned incandescent bulbs, kick-starting the process with a three-month public consultation on whether their sale should be restricted. Of course, that should be the case - and such a decision should be backed by legislation.

The government wants to outlaw the sale and supply of incandescent bulbs starting with ones of 25 watts or more that fail a minimum energy-efficiency standard. It contends that if all were replaced with compact fluorescent and light-emitting diode bulbs, electricity bills would be HK$390 million less a year and our two power stations would emit 273,000 tonnes less carbon. Put in more digestible terms, saving 1 kilowatt hour a day, the amount burned by a 100-watt bulb over 10 hours, could mean paying HK$365 less over a year. The newer bulbs cost at least three times more, but the savings are not only worthwhile but, for the sake of sustainability, necessary.

Those are persuasive arguments, but common sense does not always prevail. Chief Executive Donald Tsang Yam-kuen's 2009 policy address announcement of a HK$100 voucher scheme for the purchase of low-energy bulbs was derailed by revelations that one of his in-laws was a major light-bulb supplier. Pressure from pro-business legislators and powerful lobby groups can also lead to watered-down policies that lack teeth and meaning. The idling engine law was 10 years in the making and the 20 exemptions are so far-reaching that what was such a worthy idea when first raised is unlikely to have much impact on roadside pollution levels when it finally takes effect next month.