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August 3rd, 2011:

Curious contradiction between the model and the reality

South China Morning Post – 3 Aug 2011

A recent report by the think tank Civic Exchange, “Roadside Air Pollution in Hong Kong: Why is it still so bad?”, draws attention to the curious contradiction in the government’s figures on polluting emissions. The Environment Bureau’s public consultation document – “Air Quality Objectives Review” – trumpets the success of what the bureau likes to call the “series of stringent measures” it has put in place since 1990 to reduce emissions from various sources, such as power stations and vehicles.

By 2007, it said, these measures had led to a decline by roughly half in the pollutants sulphur dioxide, nitrogen oxides, respiratory suspended particulates, volatile organic compounds and carbon monoxide. These figures are derived by modelling, rather than by actual measurement.

That is, the government creates a model, based on the theoretical performance of these sources. However the bureau’s report also contains another set of data, showing the concentrations of the same pollutants as either flat or increasing. This data is based on empirical monitoring of the air.

The bureau notes this contradiction somewhat obliquely, in terms that could have come straight out of the British television programme Yes Minister’s guide to bureaucratic language: “It is apparent that the extent of the air quality improvement is not commensurate with the extent of emission reduction achieved over the past two decades …”

Firstly, one has to wonder why the bureau chose to play up the data derived from its model, rather than the data measuring the actual state of the air.

Secondly, Civic Exchange’s paper, by Dr Michael Edesess, a visiting fellow at the Hong Kong Advanced Institute for Cross-Disciplinary Studies, argues that the government’s model is flawed, in that it depends on the different sources performing at optimal level. In theory, a bus with a Euro V-standard engine produces six times less polluting emissions than a bus with a Euro I-standard engine. But if the Euro V bus is poorly maintained, then its emissions can be up to 20 times greater then its theoretical design. Edesess says that the difference in emissions between well and poorly maintained vehicles can be enormous. He notes that studies in the US city of Denver showed that “since 1999, one automobile in 20 emits more than the other 19 combined”.

He says the bureau’s model does not take account of poorly maintained vehicles. Edesess concludes that there needs to be more stringent inspection of vehicles and penalties for poorly maintained vehicles.

However, as a number of groups have been saying for some time, the government needs to introduce a more attractive scheme of accelerated depreciation and give subsidies to bus companies and truck owners to scrap their old vehicles. This is money that would be well-spent, but it’s not a programme the government shows any sign of taking any interest in, despite paying lip service to its concern for public health