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A spokesman for the Environmental Protection Department said today (March 22) that respirable suspended particulates (RSP) and Nitrogen Dioxide (NO2) are the major causes of roadside air pollution problem. Both pollutants affect human health. To improve roadside air quality, the Government installed particulate reduction devices on old diesel vehicles which helped reduce substantially the level of RSP concentration at roadside. In addition, the Government is also implementing measures to reduce emission of nitrogen oxide (including NO2) by vehicles.
To reduce the impact of RSP emitted from diesel vehicles on the public, the Government has been progressively tightening the emission standards of new vehicles (which includes the early introduction of Euro V emission standard) and mandated the installation of particulate reduction device (e.g. oxidation catalysts) on pre-Euro vehicles. Franchised buses companies also retrofitted Diesel Oxidation Catalysts (DOC) on their Euro I buses and diesel particulate filters (DPF) on their Euro II and III buses. DOC can reduce about 30% of RSP emitted from Pre-Euro and Euro I vehicles, while the DPF can reduce about 80% of RSP emission. Hong Kong's roadside RSP concentration has been reduced by 34% when compared to 1999. Other modern cities also adopted similar measures to reduce the impact of RSP emission from diesel vehicles.
In addition to direct emissions from vehicles, roadside NO2 also arises from the photochemical reaction of Nitric Oxide (NO) from vehicles with Ozone (O3) or Votalile Organic Carbon (VOC). As such, the increase of roadside NO2 level is caused by a number of factors including improper vehicle maintenance and high ambient O3 level, etc.
To further improve the roadside air quality, we agree that it is necessary to reduce Nitrogen Dioxide emissions. The Policy Address last year already announced that we would introduce a trial scheme of retrofitting on Euro II and III franchised buses with "Selective Catalytic Reduction" devices to reduce nitrogen oxides emissions to a level comparable to Euro IV buses. The Government undertook to fully subsidise the installation cost if the trial was successful. We also proposed to set up low emission zones at busy corridors in Causeway Bay, Central and Mong Kok. We are also preparing a proposal to strengthen the control of emissions from petrol and LPG vehicles (including the use of roadside remote sensing equipment and the use of dynamometers for emission testings). We will consult relevant stakeholders when the proposal is ready.
"We believe the implementation of these measures will help tackle roadside air pollution problem caused by NO2," the spokesman said.
Ends/Tuesday, March 22, 2011
Issued at HKT 20:22
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