LEGISLATORS voted against the proposal based on the wrong premise. They wanted evidence that petrol is more 'environmentally friendly' than diesel. Neither are environmental-friendly because both emit harmful pollutants. Also, the exhaust emissions of the two types of vehicles are inherently different. Comparing their relative environmental-friendliness is misguided.
A more useful way to assess the public health benefits of the scheme is to start by examining Hong Kong's air quality objectives. These are the air quality standards which should be met.
The one standard which Hong Kong consistently fails to meet by a substantial margin is the level of respiratory suspended particulates (RSP). Its adverse effect on health includes serious respiratory and cardiovascular illnesses, with the elderly and children being most susceptible.
It is accepted that the biggest culprit for the emission of RSP in Hong Kong right now is the diesel fleet. It is for this reason that we need to address RSP quickly and efficiently.
The administration's proposed scheme targets diesel vehicles below four tonnes. This includes taxis, public light buses, school buses and light goods vehicles. There is enough available data to assess reasonably accurately how much RSP levels would be reduced.
Opponents argue that while RSP can be brought down, other pollutants such as carbon monoxide and dioxide, plus benzene levels would increase. This is true, but the expected increases are relatively small and, most importantly, the air quality objectives for them can still be met comfortably.
For some reason, many legislators prefer to ignore this and instead argue that they do not trust the Environmental Protection Department's (EPD) data. Having said that, it was frustrating that officials were not more aggressive in countering many groundless arguments. Perhaps technocrats are not trained for such combat, when they need to be in such an assertive political environment.
