For a city that has been choking in the fumes produced by its growing fleet of vehicles, any progress in reducing emissions counts. So it is heartening to learn that the trend of worsening air quality has apparently been bucked.

During the 12 months to June, the general monitoring stations recorded a 91 per cent drop in the number of hours in which the air pollution index was 'very high'. On the road side, there has been a 45 per cent reduction in Central, Mongkok and Causeway Bay, the SAR's most popular commercial districts and air pollution black spots. The improvement was attributed to the introduction of taxis running on liquefied petroleum gas (LPG) and buses using cleaner diesel. Yet much more still needs to be done to meet the goals set by Chief Executive Tung Chee-hwa in his policy address in 1999 - slashing the amount of harmful particulates that can be inhaled by 60 per cent by the end of 2003 and 80 per cent by 2005, and cutting vehicle nitrogen oxide emissions by 30 per cent by 2005.

One measure in the pipeline is phasing out diesel minibuses. Officials are considering giving grants to buyers of LPG minibuses, similar to what were offered to LPG taxi owners. But minibus owners have seized the opportunity to seek to increase seating capacity from 16 to 24 in exchange for both using cleaner fuel and installing the Octopus card payment system and seat belts. These features are good in their own rights. But haggling over how they could be introduced should not be allowed to delay the introduction of LPG minibuses to alleviate air pollution.