(Reprinted from HKCER Letters, vol.25, March-July 1994)


Letter to the Editor - HKCER Letters


We read with interest the essay entitled "Vehicular Emissions in Hong Kong: Facts and Policy Analysis" published in your January issue. However, we are concerned that the authors seem to have come up with certain policy recommendations which may not be fully justified. This concern arises from the following observations:

(a) We think that the essay does not present the whole picture and there is a need to look at the vehicle emission problem comprehensively, rather than to focus too narrowly on a specific contribution. The administration has adopted and is in the process of implementing a long-term motor vehicle emission control strategy, consisting of many elements, only some of which are touched on in this essay.

(b) There is no assessment of whether the action proposed by the writers for limiting emissions from heavy-duty vehicles will be sufficient in itself to achieve the necessary improvement in the state of Hong Kong's air. That is, there is no assessment that merely applying such controls in the face of a rapidly growing number of vehicles, and taken together with the many other air pollution sources in Hong Kong, will provide healthy air on a sustainable basis. Protection of the environment needs deeper consideration than only adopting a "low-cost" option.

(c)The statement that the government has begun to reduce the duty differential between unleaded and leaded petrol and has plans to eliminate it altogether is wrong. The government has not reduced the duty differential. In fact, the duty differential has increased progressively from 45 cents per liter to 60 cents per liter from April 1991 to April 1994, thus holding its value relative to the absolute level of leaded petrol duty constant at around 11 percent. Furthermore, the government does not have a plan to eliminate the differential altogether.

(d) The statement that "switching to petrol is more costly and less effective than adopting higher grade diesel fuel" is not supported by any cost analysis. Similarly, the statement that "a 'petrol-only' policy may well result in costs that far exceed the benefits" is also unaccompanied by a quantitative evaluation of either.

(e) The emission matrix in Table 1 is wide of the mark. It underestimates the contribution of PLBs and overestimates the contribution of private cars to particulate matter emissions. We believe that this is partly due to the selection of vehicular emission factors inappropriate to the Hong Kong vehicle fleet. Attributing only 4 percent of particulate vehicular emissions in Mongkok to PLBs and 9 percent territory-wide to private cars simply does not accord with basic data and even casual observation.

Reconsideration of the authors' work in light of the above comments would most likely lead to different conclusions on appropriate vehicle emission control policy options for Hong Kong, certainly with respect to how we deal with emissions from a fleet of public transport operators who are using highly polluting diesel technology due to a historic quirk of the low duty levied on diesel fuel. We will shortly be publishing the government's position on these issues.

Mr. Alex K.Y. Ng
For Director of Environmental Protection


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