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Press Release
Emissions of LPG taxis
In response to media reports today (November 5) about a study by the Hong Kong Polytechnic University showing that liquefied petroleum gas (LPG) taxis polluted more than diesel taxis, a spokesman for the Environmental Protection Department (EPD) said that before introducing LPG taxis into Hong Kong, vehicle manufacturers were asked to provide detailed information to prove that these LPG taxis were more environmentally friendly than diesel taxis.
Evidence shows that nitrogen oxides emitted by diesel taxis were 18 to 100 times more than those emitted by LPG taxis, the EPD spokesman said. Particulate emissions of LPG taxis were extremely low and their emissions of carbon monoxide and hydrocarbon were also lower than diesel taxis, the spokesman added.
The EPD, after examining the study report and liaising with Dr Chan Tat-leung, a key researcher in the Polytechnic University study, found that the study clearly supported the fact that the replacement of diesel taxis by LPG taxis had effectively alleviated urban street air pollution. The report also pointed out that LPG taxis needed proper maintenance as the vehicles got older.
It was also noted that a paper carried findings that at a speed of 50 kilometres per hour, LPG taxis would emit 0.07 grams of nitrogen monoxide per kilometre while diesel taxis would emit 0.05g of nitrogen monoxide per kilometre. These figures did not tally with the report. As confirmed by the Polytechnic University, findings in the report in fact showed the emission of nitrogen monoxide by diesel taxis was 0.18g per kilometre.
Dr Chan said that the study did not consider particulate emissions. It focused on the use of roadside remote sensing technology to measure emissions of LPG vehicles and the effect of maintenance on such vehicles. The emission data of diesel taxis in the study was based on estimates derived from random samplings at the roadside conducted some years ago. There were differences in location, timing, road surface and driving conditions as compared with the current study. All the diesel vehicle emission data can only be used for reference. The LPG taxi emissions should also be further studied.
The spokesman said the EPD was working on a proposal to control emissions from petrol and LPG vehicles, which involved the deployment of roadside remote sensors and chassis dynamometers to test vehicular emissions. A consultation would be carried out next January.
Ends/Monday, November 5, 2007
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