LCQ11: Measures to improve air quality

     Following is a question by the Hon Tanya Chan and a written reply by the Secretary for the Environment, Mr Edward Yau, in the Legislative Council meeting today (December 21):


     Regarding efforts to improve air quality and update air quality reports, will the Government inform this Council:

(a) given that most environmental protection authorities in major countries worldwide make public their air pollution control measures and the effectiveness of these measures annually (e.g. Mainland's Ministry of Environmental Protection published five brief periodic reports on emission reduction in respect of major pollutants in 2011), yet the Environmental Protection Department (EPD) in Hong Kong does not publish similar periodic reports at present, and that apart from the annual updating of the report entitled "Air Quality in Hong Kong", the latest study report on the EPD web site was compiled two years ago, of the reasons why EPD has not updated study reports on air quality in Hong Kong or on air quality improvement for a long time;

(b) given that the SAR Government and the Guangdong Provincial Government have jointly implemented the air quality improvement measures under the Pearl River Delta Regional Air Quality Management Plan with a view to meeting the targets of reducing the emission of four major air pollutants, namely sulphur dioxide, nitrogen oxides, respirable suspended particulates and volatile organic compounds by 2010, whether the two Governments have set new emission reduction targets; if they have, of the new targets; if not, the reasons for that; and

(c) given that the Chief Executive (CE) stated in the 2010-2011 Policy Address that the Government and franchised bus companies were conducting a trial to retrofit Euro II and Euro III buses with selective catalytic reduction devices to reduce emission of nitrogen oxides from these buses, and that CE also announced in the 2011-2012 Policy Address the provision of subsidies to owners of liquefied petroleum gas taxis and light buses to help them replace catalytic converters in their vehicles, yet a study report indicated that selective catalytic reduction devices might increase the level of nitrogen oxides, whether such a situation has arisen in the trial scheme of retrofitting buses with catalytic reduction devices (trial scheme); as the authorities advised at the meeting of the Panel on Environmental Affairs of this Council held in July 2010 that they would endeavour to have the initial results of the trial scheme ready by end 2011, of the progress at present; whether the authorities have any plan to submit the report on the trial scheme to this Council?



(a) The Environmental Protection Department publicises the details and effectiveness of our air pollution control measures through the annual air quality report and the bi-annual reports submitted to the Panel on Environmental Affairs of Legislative Council (LegCo) on the progress of the various air quality improvement measures implemented in Hong Kong and Pearl River Delta (PRD) region under the PRD Regional Air Quality Management Plan. We have uploaded the reports published in 2011 to the following web pages of the Department for public access:

(i) Air Quality in Hong Kong 2010:

(ii) Progress of Measures under PRD Regional Air Quality Management Plan:

     Moreover, we shall consult the LegCo and other stakeholders and upload the relevant information to the Department's website for public access whenever we have plan to launch new air quality improvement measures. The progress of these measures will also be elaborated in the reports prepared under the PRD Regional Air Quality Management Plan.

(b) To continue improving the air quality in the PRD region, the two governments are working in earnest to implement the emission reduction measures under the PRD Regional Air Quality Management Plan, which focus on power plants, motor vehicles and the more polluting industrial processes. The two governments are now conducting the final assessment on achieving the 2010 emission reduction targets.  On the basis of the final assessment, the two governments will seek to complete a joint study on the emission reduction arrangements for the next phase and set emission reduction targets to further improve regional air quality.

(c) Catalytic converters are devices making use of catalyst media used for reducing motor vehicle emissions. They come in different forms in terms of applications to different types of vehicle. "Three-way catalytic converters" are applied to petrol and LPG vehicles. This type of converter oxidises harmful carbon monoxide and hydrocarbons to carbon dioxide and water, and reduces nitric oxide and nitrogen dioxide to nitrogen and oxygen.  In general their emission reduction efficiency can be over 90%.  If vehicle owners do not replace the worn out three-way catalytic converters in time, the vehicle emissions would be increased drastically. As for the "diesel oxidation catalysts" referred to in a research report published by academics of the Chinese University of Hong Kong earlier, they reduce suspended particulates (including PM2.5), carbon monoxide and hydrocarbons emissions through an oxidisation process. During the process, it may oxidise some of the nitric oxide (NO) in the exhaust gas into nitrogen dioxide (NO2).

     In recent years, vehicle manufacturers began to use selective catalytic reduction (SCR) devices to reduce nitrogen oxides (NOx) (including NO and NO2) from the emissions of diesel vehicles. According to overseas experience, it can effectively reduce the NOx emissions by about 60%. Since NO will further oxidise to NO2 in the atmosphere after being emitted from vehicles, reducing NOx emissions from vehicles (in particular franchised buses, which make up an important part of the vehicles running in urban areas) is the key to tackling the problem of local roadside NO2 pollution.

     Regarding retrofitting Euro II and III franchised buses with SCR devices, we have retrofitted three buses (comprising two Euro II and one Euro III buses) with SCR devices for trial in September 2011. We are now retrofitting another three buses (also comprising two Euro II and one Euro III buses) for trial.  We expect that the retrofit can be completed in February 2012. We will review the initial results after the first six months of the trial to understand as soon as possible the feasibility of retrofitting these Euro II and III buses with SCR devices on a large-scale and their effectiveness in reducing air pollutants, and report the initial trial results to the Subcommittee on Improving Air Quality under the Legislative Council Panel on Environmental Affairs.

Ends/Wednesday, December 21, 2011
Issued at HKT 18:08