Keeping Hong Kong's taxi and minibus fleet clean for cleaner air

Freda Fung welcomes government efforts to ensure emission control devices in taxis and minibuses are well maintained, so as to cut pollution

PUBLISHED : Friday, 09 August, 2013, 12:00am
UPDATED : Friday, 09 August, 2013, 2:36am

Last week, the Environmental Protection Department announced details of a subsidy programme to replace catalytic converters and oxygen sensors on taxis and minibuses that are run on liquefied petroleum gas, and said that a more rigorous emission-testing regime for petrol and LPG vehicles will be implemented next April.

It is encouraging to see the government putting its money where its mouth is - taxis and minibuses are a major source of roadside pollution, contributing to 39 per cent of nitrogen oxides and 55 per cent of hydrocarbon emissions in urban corridors; and nearly all taxis and two-thirds of minibuses are powered by LPG.

Ironically, a decade ago, LPG taxis and minibuses were hailed as a clean alternative to diesel. At that time, the government offered incentives for taxi and minibus owners to replace their diesel vehicles with LPG ones. So why have these "clean" vehicles now become a source of choking pollution? Lack of maintenance is the root cause.

Taxis and minibuses typically clock over 140,000 kilometres and 100,000 kilometres a year respectively. This means they are driven, respectively, over 13 times and nine times more than an average private car. While the fuel they burn is cleaner than diesel, these vehicles still need to rely on emission control devices (such as catalytic converters and sensors) to keep emissions low. But with such high usage, their emission control devices need more frequent repairs or replacement.

The current mandatory annual emissions tests for petrol and LPG vehicles are not capable of identifying those with excessive emissions and do not measure nitrogen oxide emissions, as a recent Civic Exchange study discovered. So vehicles with defective catalytic converters (80 per cent of LPG taxis and 45 per cent of LPG minibuses) can still have their licences renewed.

The LPG story illustrates well why an inspection and maintenance programme is a critical part of Hong Kong's vehicle emissions control efforts.

For all the control measures - whether it is encouraging replacement of dirty trucks, retrofitting buses with nitrogen oxide after-treatment devices, or establishing low emissions zone for buses - the new or retrofitted vehicles need to be maintained well in order for the control devices to remain effective.

Therefore, following the good example of upgrading the petrol and LPG vehicle emissions test, the government should start developing an improved emissions-testing programme for another important pollution source: diesel trucks and buses.

And, as important as it is to keep in-use vehicles clean and well maintained, it is equally important that new vehicles become cleaner over time. To achieve that, we urge the government to set up a timetable for enforcing world-class vehicle emission standards, such as Euro 6 standards, or the world's strictest standards, adopted in California.

This would enable Hong Kong to reap the benefits of the most advanced emission-control technologies being used on the cleanest cars and trucks.

We hope that, with a concerted effort to control emissions from new and in-use vehicles, the goal of improving roadside air quality and reducing public health risks can be met by the end of the decade.

Freda Fung, a consultant with Civic Exchange, is director of Fung Research Limited



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