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Following is a question by the Hon Lui Ming Wah and an oral reply by the Secretary for the Environment, Transport and Works, Dr Sarah Liao, in the Legislative Council meeting today (February 11):

Question:

Regarding the air pollution in Hong Kong and its impact on health, will the Government inform this Council whether it has conducted studies to find out:

(a) the sources of various air pollutants in Hong Kong and the changes in the concentration of these pollutants according to the authorities' air pollution index over the past five years; if it has, of the findings;

(b) the impact of changes in the air quality of the Pearl River Delta Region on that of Hong Kong over the past five years; if it has, of the findings; and

(c) the relationship between the air pollution in Hong Kong and the local respiratory and heart diseases, and the number of persons who have contracted these diseases due to air pollution, as well as their percentage in the total number of patients who suffer from the diseases concerned; if it has, of the findings?

Reply:

Madam President,

(a) The pollutants in the air in Hong Kong come from emission sources located in Hong Kong and in the other areas of the Pearl River Delta (PRD) Region. Taking the whole of the PRD Region, the percentage shares of the four major sources in the emission of the four major pollutants in the air are as follows.

Air pollution is a relatively complicated issue, so I will try to explain it more clearly. I will talk about three major sectors - the energy sector, the industrial sector and also vehicles. First of all, let me talk about the emission of the PRD economic region, including Hong Kong, which is in the same air shed.

The energy sector accounts for 54% of the sulphur dioxide (SO2), 42% of the nitrogen oxides (NOx) and 15% of the respirable suspended particulates (RSP) emitted by all sources in the Region. The industrial sector accounts for 39% of the SO2, 13% of the NOx, 60% of the RSP and 11% of the volatile organic compounds (VOC) emissions. Motor vehicles account for 31% of the NOx, 14% of the RSP and 55% of the VOC emissions. In addition, consumer products containing VOC account for 23% of the VOC emissions. This is the emission situation of the whole PRD region including Hong Kong.

Taking only the major emission sources located in Hong Kong, their emission shares would be as follows.

The energy sector accounts for 86% of the SO2, 54% of the NOx and 35% of the RSP emitted by all local sources. The industrial sector accounts for 8% of the SO2 and 16% of the VOC emissions. Motor vehicles account for 27% of the NOx, 44% of the RSP and 25% of the VOC emissions. Consumer products containing VOC account for 53% of the VOC emissions. The figures I have just read out show that there are differences between emissions in Hong Kong and those in the rest of the PRD region because our energy sector and our industrial sector are different from those in the PRD region.

Over the past five years, the average concentrations of air pollutants recorded at the roadside air quality monitoring stations have been experiencing a downward trend: the average concentrations of SO2, NOx and RSP have dropped by 41%, 23% and 13% respectively.

As regards the situation at the general air quality monitoring stations, the average concentrations of SO2 and NOx have dropped by 6% and 11% respectively during the same period. The average concentration of RSP has risen by 4%. There is another pollutant not included among the four that I have mentioned already, and that is ozone. The average concentration of ozone has risen by 18%. Ozone is not directly emitted from any source, and is formed under photochemical reaction between NOx and VOC under sunlight.

(b) As mentioned in section (a) above, the average concentrations of the major air pollutants as recorded at the roadside air quality monitoring stations have been dropping over the past five years. If we count the time when the Air Pollution Index exceeded the level of 100, the reduction is 35% in the same period. This indicates that the measures we have been implementing to reduce motor vehicle emissions over the past few years have effectively improved air quality at the roadside.

However, there has not been much reduction in the concentrations of pollutants in the general ambient air. Taking RSP, its average concentration has been on an increasing trend. If we count the time when the Air Pollution Index exceeded the level of 100, there has been an increase of 8%. This reflects that the problem of regional air quality has not improved much in relative terms, and its impact on the air quality in Hong Kong is particularly serious under certain meteorological conditions. To improve regional air quality, the Hong Kong SAR Government and the Guangdong Provincial Government have jointly drawn up a Regional Air Quality Management Plan. I have reported the detailed contents of the Plan to the Panel on Environmental Affairs on 14 January 2004.

(c) The Environmental Protection Department, the University of Hong Kong and the Chinese University of Hong Kong carried out in 2002 a study on the correlation between air pollution in Hong Kong and its impact on health. The study made use of the air quality data between 1995 to 2000 and the data on daily admissions at 12 public hospitals of the Hospital Authority to assess the correlation between air pollution and respiratory and cardiovascular illnesses in Hong Kong. According to the findings of the study, in 2000 the admission to hospital of 3770 patients with respiratory illness and 3970 patients with cardiovascular illness could have been correlated with air pollution. The numbers account for 4.2% and 5.8% respectively of the total number of patients admitted to the hospitals for respiratory and cardiovascular illnesses.

Ends/Wednesday, February 11, 2004

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