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    Following is a question by the Hon Emily Lau and a written reply by the Secretary for the Environment, Transport and Works, Dr Sarah Liao, at the Legislative Council meeting today (May 4):

Question:

    Regarding the Air Quality Objectives ("AQOs"), will the Executive Authorities inform this Council:

(a)  given that the Secretary for the Environment, Transport and Works advised this Council on November 10 last year that "considerations such as the prevailing exposure levels, technical feasibility, source control measures, abatement strategies, and social, economic and cultural conditions should be taken into account when setting air quality standards for a particular place", whether the Administration will review the AQOs, adopted since 1987, based on such considerations; if so, of the scope and timetable of the review; if not, the difficulties in carrying out a review based on such considerations (particularly social, economic and cultural conditions);

(b)  given that the percentages of time at which Hong Kong air complied with the short-term AQOs were 94% and 86% in 2003 and 2004 respectively, whereas those which complied with the long-term AQOs during the same periods were 62% and 15% respectively, of the reasons for the discrepancies between the percentages of time which complied with short-term AQOs and those complied with long-term AQOs;

(c)  of the measures to help members of the public to distinguish between long-term and short-term AQOs; and

(d)  of the respective total numbers of times in 2003 and 2004 at which "the hourly average concentration of sulphur dioxide" and "the daily average concentration of respirable suspended particulates", as recorded by the monitoring stations of the Environmental Protection Department, exceeded the relevant standards set by the AQOs, as well as the follow-up actions taken when such standards were exceeded?

Reply:

Madam President,

(a)  The Government has been closely monitoring the reviews of air quality standards conducted elsewhere. We will make reference to the results of the reviews in the United States (US), European Union (EU) and other developed countries, in conjunction with information obtained from on-going local studies, when considering the need for revising Hong Kong's Air Quality Objectives (AQOs) from a scientific perspective. Due consideration will be given to all relevant factors, including the prevailing exposure levels, technical feasibility of new objectives, effectiveness of source control measures, progress in the implementation of abatement strategies, and economic and social implications. According to the latest information, the EU review and the US review are expected to be completed in the latter half of 2005 and by the end of 2007 respectively. We will draw up a concrete timetable for reviewing the local AQOs after considering the results of these reviews.

(b)  Long-term AQOs refer to the permissible limits on the annual average concentrations of pollutants, whereas short-term AQOs are the permissible limits on the 1-hour and 24-hour average concentrations of pollutants.

    The low compliance rate with the long-term AQOs at air quality monitoring stations in 2004 was chiefly attributable to worsening regional air pollution. As the background concentrations of pollutants in the region increased, the readings at many monitoring stations exceeded the long-term AQOs. As for short-term AQOs, they were exceeded mainly when the wind was weak or the meteorological conditions favoured the formation of photochemical smog. As such weather conditions only occurred occasionally, the percentage time in the year that the short-term AQOs were met was higher than the compliance rate with the long-term AQOs.  

(c)  On its website, the Environmental Protection Department has explained in detail the AQOs, the computation of Air Pollution Indices and their health implications. The information includes the different implications of the long-term and short-term AQOs and the compliance status of these AQOs at monitoring stations. Members of the public may visit the following website:

    http://www.epd.gov.hk/epd/english/environmentinhk/air/air_quality/air_quality.html

(d)  In 2003 and 2004, the hourly average concentrations of sulphur dioxide recorded by all monitoring stations in Hong Kong were within the permissible limit. No exceedance was recorded.

    As for respirable suspended particulates (RSP), statistics on the exceedances of the daily average limit are as follows:

Year            Number of Monitoring Stations Recording Exceedances
                              of RSP Daily Average Limit
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       Never    One Day    Two Days    Three Days   Four Days or above
       *****    *******    *******    *********    *******************
2003    2           4          6            2               0
2004    5           2          5            2               0

    Although weather conditions play a part in causing exceedances of the AQOs, the ultimate solution to our air pollution problem is to reduce emissions of pollutants. To address the problem, the Government has taken measures to control local emissions and strengthened its co-operation with the Guangdong Provincial Government in reducing air pollutant emissions in the Pearl River Delta Region with the aim of achieving good air quality in Hong Kong as soon as possible.

Ends/Wednesday, May 4, 2005

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