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Reply from EPD

Dear Mr Furner,

Thanks for your enquiries about PM2.5 measurement on 28 August.

PM2.5 is a major part of PM10, accounting for 60% to 70% of the total mass concentration of the latter measured in Hong Kong.  The measurement of PM10 can therefore effectively reflect the levels of PM2.5.  As the sources of PM2.5 are also common to PM10, e.g., power plants, vehicles, industrial sources, etc., the government’s efforts to reduce PM10 concentrations can effectively reduce PM2.5 levels.

To understand the nature and characteristics of the PM2.5 in HK and their correlation with PM10, we have been conducting different projects including speciation studies (analysis of the chemical composition of PM2.5) and continuous measurement at 5 sites in HK.  From time to time, the PM2.5 data from these projects are provided to and used by public members including academics and media for studies and reporting, and are included in different publications and reports.  Here are a few of them :

To enhance our monitoring of PM2.5, we are working to extend the PM2.5 continuous measurement to all stations in Hong Kong with a view to making it a regularly monitored and reported pollutant.  We are now taking steps to install and test PM2.5 samplers in all monitoring stations.  The test runs of the samplers in the network are expected to be completed by end of this year.

From our previous studies and research findings from our local academics, a very significant proportion of particulates including PM10 and PM2.5 measured in Hong Kong are contributed by regional sources.  According to a study by the Hong Kong University of Science and Technology in 2005, the contribution of particulates from regions outside Hong Kong (including Pearl River Delta Region and regions outside PRD) could be some 60% on an annual basis and even higher at 70% during winter.  To alleviate the particulates problem, we have been working with Guangdong Provincial Government on a regional air quality management plan to reduce emissions in the PRD region and making substantial efforts to reduce local emissions of these particulates, in particular those from two major sources, namely power plants and motor vehicles.  Measures implemented in the past years include:

  • Power sector – banning new coal-fired generation units since 1997, imposing stringent emission caps on power plants since 2005, requiring power plants to increase the use of natural gas for electricity generation, requiring retrofitting of advanced air pollution control equipment to existing coal-fired generation units,
  • Motor vehicles – requiring the use of cleaner motor vehicle fuels such as LPG and the virtually sulphur-free Euro V diesel and petrol, mandating the retrofit of particulate reduction devices in pre-Euro diesel vehicles, subsidizing the replacement of old commercial diesel vehicles and providing tax incentives for environment-friendly vehicles.  Franchised bus companies have also retrofitted their Euro II and III buses with diesel particulate filters, which could reduce their particulates emissions by over 80%.

The above efforts have borne fruits.  Between 2005 and 2010, the annual PM2.5 concentrations in Hong Kong reduced by 26%.  The results of our speciation studies show that, between 2001 and 2009, the levels of elemental and organic carbon compounds (which are major constituents of PM2.5 coming from motor vehicles) at the roadside have reduced by more than 50%.  This clearly reflects that our control measures implemented in the past decade have very effectively reduced the PM2.5 emissions from our local vehicle fleet.

Despite the above improvements, the Government is endeavouring to introduce more new measures for improving the air quality including cutting of particulate emissions, such as requiring the power companies to maximize the use of the existing natural gas-fired generation units, thereby increasing the share of natural gas in local electricity generation to about 50%; and to prioritize the use of those coal-fired generation units equipped or retrofitted with advanced air pollution control equipment, so as to further tighten the already very stringent emission caps by about 30 to 50% from 2015; introducing relevant regulations to promote energy efficiency for electrical appliances and buildings; proposing emission standards for non-road mobile sources; implementing a host of new measures to reduce emissions from the transport sector, such as a ban on idling vehicles with running engines, a subsidy to encourage early replacement of Euro 2 diesel commercial vehicles with new ones, a trial of retrofitting franchised buses with “Selective Catalytic Reduction” devices to reduce emissions and the Government to fund the retrofit if the trial is proved to be successful; designating pilot Low Emission Zones at busy corridors in Causeway Bay, Central and Mong Kok and setting up a Pilot Green Transport Fund to encourage introducing innovative transport technology, etc.

Best regards,
C. F. Chow, (Mr.)

Senior Environmental Protection Officer, Acting
Environmental Protection Department

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