Los Angeles Mayor Antonio Villaraigosa was diplomatic enough to refrain from saying at a luncheon address yesterday how Hong Kong should go about cleaning up its air. After all, Sarah Liao Sau-tung, our environment secretary, sat near him as he talked of how the US city known for its heavy smog took tough measures to cut vehicle emissions. It is to be hoped that the passion displayed by Mr Villaraigosa rubbed off on Dr Liao. It is not that she has been a laggard in battling air pollution. The former environmental consultant, who helped Beijing make its clean-air pledge in bidding for the 2008 Olympics, has demonstrated that she knows how to force her way through the bureaucracy. What is not so sure, however, is whether she and Chief Executive Donald Tsang Yam-kuen have the bravado to tap the community's strong aspirations for clean air to override opposition from vested interests. On radio yesterday, Mr Tsang seemed in denial mode when he said small particulates blowing from the mainland caused haze and affected our feelings, but not what we breathed. In fact, particulates are dangerous to our health as they penetrate into our bodies. Dr Liao yesterday talked of consulting the public on introducing laws to require idling vehicle engines to be switched off, and when asked about setting up refuelling stations near the border to encourage cross-border vehicles to use cleaner fuel, said the government must consider the feasibility of such an initiative. Once again, the C words - consultation and consideration - hold sway. Combating pollution that originates in Guangdong is a difficult undertaking. But the government's reluctance to take stringent action to reduce vehicle emissions, which account for 25 per cent of local air pollution, is disappointing. On Wednesday, Mr Tsang announced a HK$3.2 billion scheme to encourage old diesel vehicles to get off the road. The first-registration tax for low-emission vehicles will also be cut by 30 per cent. These are welcome and long-overdue measures. What the government should do - but hasn't - is ride on the political appeal of these initiatives to force through other tougher measures, such as electronic road pricing and a timetable to force old vehicles off the road. Instead, what we get is another round of consultation on idling engines. Even if the government took action now, it could not be accused of doing so with indecent haste as the measure has had a long gestation period. The measure that requires thorough consultation and consideration, which the government is not undertaking, is road pricing. After Sars in 2003, Mr Tsang forced through legislation to raise the fine for littering to HK$1,500. We should not have to wait for people to start dropping dead because of foul air for stringent measures to avert a further decline in air quality. Worsening respiratory problems have already prepared people for tough action.