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Following is a question by the Hon Albert Chan and a written reply by the Secretary for the Environment, Mr Wong Kam-sing, in the Legislative Council today (January 20):
Question:
In reply to my oral question raised on January 7 last year, the authorities indicated that the air quality in Tung Chung had been improving progressively in the past five years from 2010 to 2014. However, quite a number of Tung Chung residents have relayed to me that the air pollution problem in Tung Chung has not been alleviated in recent years and has shown signs of deterioration instead, with the problem being more acute in summer time. In this connection, will the Government inform this Council:
(1) of the respective numbers of times, as recorded by the air quality monitoring station in Tung Chung last year, in which the concentrations of fine suspended particulates (i.e. PM 2.5), ozone, sulphur dioxide, nitrogen dioxide and carbon monoxide exceeded the Air Quality Objectives or other relevant objectives, and the details of the exceedance of each type of pollutants, including the respective average and maximum extent of exceedance and concentrations;
(2) whether the authorities analysed the major sources of air pollutants in Tung Chung last year; if they did, of the outcome, including the percentage of aircraft emissions in the pollutants; if not, the reasons for that; and
(3) whether it has formulated targeted measures to improve the air quality in Tung Chung; if it has, of the details; if not, the reasons for that?
Reply:
President,
(1) We are still validating the air quality monitoring data for 2015 as the year has just come to an end. According to the preliminary analysis conducted by the Environmental Protection Department on the data recorded at the Tung Chung Air Quality Monitoring Station, the air quality in Tung Chung improved gradually between 2011 and 2015. The annual average concentration of respirable suspended particulates (PM10), fine suspended particulates (PM2.5), nitrogen dioxide, sulphur dioxide and carbon monoxide dropped 23 per cent, 31 per cent, 20 per cent, 38 per cent and 11 per cent respectively, while that of ozone increased by two per cent over the same period. Please refer to Annex 1 for details.
Except for nitrogen dioxide and ozone, the air quality in Tung Chung in 2015 attained the current Air Quality Objectives (AQOs). For nitrogen dioxide, the hourly average concentration limit was met but the annual average concentration limit was exceeded by about 1 ¦Ìg/m3 (i.e. three per cent). For ozone, the number of times exceeding the 8-hour average concentration limit was 19 (more than "9 times" as allowed under the AQOs), with the highest level at 242 ¦Ìg/m3, which was 82 ¦Ìg/m3 (i.e., 51 per cent) more than the concentration limit of 160 ¦Ìg/m3. Please refer to Annex 2 for details.
(2) Ozone and nitrogen dioxide are the major air pollutants in Tung Chung. Ozone is a regional secondary air pollutant which is not released directly from pollution sources. Its formation is related to the photochemical activities among nitrogen oxides and volatile organic compounds (VOCs) emitted in the Pearl River Delta (PRD) region. Air pollutants can be accumulated when the conditions for dispersing them turn poor in the PRD Region. When coupled with light northerly to north-westerly wind, the concentration of ozone could be raised to a significant level in Tung Chung.
Nitrogen dioxide mainly comes from nitrogen oxides emitted from vehicles. The relatively high ozone concentration will also facilitate the conversion of nitrogen oxides into nitrogen dioxide.
As aircraft are flying at high altitudes most of the time except during landing, take-off and taxiing that are close to the ground, emissions from aircraft have little impact on the air quality in Tung Chung.
(3) Ozone and nitrogen dioxide are the major air pollution problems in Hong Kong. To improve air quality, we have been collaborating with the Guangdong Provincial Government to reduce the emissions of four major air pollutants (namely sulphur dioxide, nitrogen oxides, respirable suspended particulates and VOCs) in the PRD region and set emission reduction targets for these pollutants for 2015 and 2020. Both governments are implementing measures to reduce the emissions from power plants, factories, vehicles and vessels in the region. These measures will improve the air quality and alleviate the ozone problem in the PRD region.
In recent years, we have also launched various emission reduction measures to control local emissions. The key measures targeting the emission of nitrogen oxides are as follows:
* We have adopted an incentive-cum-regulatory approach to phase out some 82 000 pre-Euro IV diesel commercial vehicles by late 2019. An ex-gratia payment scheme was launched on March 1, 2014 to assist the affected vehicle owners. As at end 2015, about 39 000 vehicles, representing 47 per cent of the pre-Euro IV diesel commercial vehicles, took part in the scheme and were retired;
* We have deployed roadside remote sensing equipment since September 1, 2014 to strengthen the emission control of petrol and liquefied petroleum gas vehicles. We have issued Emission Testing Notices to owners of about 4 900 vehicles with excessive emissions and requested for proper maintenance;
* We have subsidised franchised bus companies to progressively retrofit their Euro II and III buses with selective catalytic reduction devices to upgrade their emission performance to a level comparable to Euro IV or above;
* We issued the Fifth Technical Memorandum at the end of last year to further tighten the emission caps of three key air pollutants from power plants from 2020 onwards. The tightened emission caps are 50 per cent to 69 per cent lower than the levels in 2010 (i.e., the First Technical Memorandum); and
* Starting from June 1, 2015, new non-road mobile machinery supplied for local use must comply with the statutory air pollution emission standards.
Ends/Wednesday, January 20, 2016
Issued at HKT 14:42
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