*************************************
Following is a question by the Hon Albert Chan and a written reply by the Secretary for the Environment, Transport and Works, Dr Sarah Liao, at the Legislative Council meeting today (March 3):
Question:
For several consecutive days in December last year, a number of places in Hong Kong, especially Tung Chung, were engulfed in smog. In this connection, will the Government inform this Council of:
(a) the number of days last year on which Hong Kong was engulfed in smog, as well as the concentration, composition and cause of the smog;
(b) the impact of ambient smog on human health and the number of consultations at public hospitals last year on illnesses triggered by smog; and
(c) the short, medium and long-term measures to address the smog problem and the estimated time for the problem to be completely solved?
Reply:
Madam President,
(a) Air pollution is the major cause of the smog phenomenon. When a temperature inversion is formed in the Pearl River Delta (PRD) Region, or when a weak northerly or northwesterly wind prevails, ambient air pollutants (including nitrogen oxides (NOx) and volatile organic compounds (VOC)) in the region will be trapped easily in the lower atmosphere and cannot be dispersed effectively. The above factors, if coupled with strong sunlight, will generate ozone under photochemical reaction between NOx and VOC and lead to the phenomenon of photochemical smog.
As ozone is a major component of photochemical smog, ozone concentration is used as a scientific indicator of the level of photochemical smog. Over the past year, among the 11 general air quality monitoring stations throughout the territory, the stations at Tap Mun and Tung Chung had records of incidents of ozone concentration exceeding the Air Quality Objective (AQO): the ozone concentrations recorded at the Tap Mun station exceeded the AQO by between less than 1% to 29% in 13 hours, whereas those recorded at the Tung Chung station exceeded the AQO by less than 1% to 26% in 26 hours.
(b) High concentrations of ozone have a greater impact on the respiratory system: it may irritate the mucous membrane lining of the nasal passage, the throat and the trachea, causing cough, chest pain and throat and eye irritation. It may also increase the system's susceptibility to respiratory infection. In serious cases, it may impair the normal pulmonary function and trigger inflammation of the respiratory system. Photochemical smog also contains other compounds such as peroxyacyl nitrates and formaldehyde, which may cause eye irritation when the concentrations are high.
We do not have information on the number of consultations at public hospitals last year associated with illnesses triggered by smog. However, 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 impacts on health. The study made use of air quality data 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, 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.
(c) To address the problem of photochemical smog, we have to reduce the emissions of NOx and VOC in the whole of the PRD Region. In this connection, we have since 1999 been implementing a programme of measures to reduce the emissions from motor vehicles in Hong Kong. We anticipate that, upon full implementation of the measures by the end of 2005, the NOx emissions from motor vehicles in Hong Kong will be reduced by 30%. So far, we have already reduced the NOx emissions from motor vehicles by 28%. Moreover, the Hong Kong Special Administrative Region Government and the Guangdong Provincial Government have jointly drawn up a "Regional Air Quality Management Plan" to reduce the emissions of four major air pollutants in the PRD Region, including NOx and VOC that are to be reduced by 20% and 55% respectively. When the targets are achieved, the ambient ozone concentrations in Hong Kong and in the whole of the PRD Region will fall significantly. The problem of photochemical smog will be alleviated and air quality will improve. Under the Regional Air Quality Management Plan, the two Governments will implement enhanced air pollution control measures, including those for reducing NOx and VOC emissions. The details of those measures are set out at the Annex. The two Governments are gradually implementing the measures with the objective of achieving, on a best endeavour basis, the agreed emission reduction targets by 2010.
Ends/Wednesday, March 3, 2004
NNNN
