Public Officer Replying : SECRETARY FOR PLANNING AND LANDS
Madam President,
(a) We have not found the need to carry out specific inspections on buildings completed in the past three years in Hong Kong to check if radioactive substances have been used in building construction. We have been conducting instead periodic surveys on the concentration of radon which, if allowed to accumulate, may pose health risks. Our findings indicate that radon levels found in our buildings are substantially below the level recommended by the World Health Organization (WHO) for remedial action to be taken.
(b) We have not conducted specific researches on the health effects of people living or working in buildings constructed with materials containing radioactive substances. As I have indicated in Part (a), our survey findings indicate that radon levels found in buildings in Hong Kong are substantially below the level recommended by the WHO for remedial action to be taken.
(c) There is at present no legislation to regulate radiation levels of construction materials. We have no intention of introducing legislative control at this time because we consider that the health risks arising from radioactive substances in construction materials commonly used in Hong Kong are negligible.
Public Officer Replying : SECRETARY FOR PLANNING AND LANDS
Madam President, a number of government departments have conducted surveys on radon indoors. For example, the Electrical and Mechanical Services Department conducts surveys on a periodic basis, basically once every two years or so, on the indoor quality of public buildings. All the survey results so far are found to be satisfactory, with the radon levels substantially below the WHO level. The Environmental Protection Department conducts territory-wide indoor surveys as well. The last one was done in 95-96, and there have been updating surveys recently. Surveys are done on residential premises as well as non-residential premises. What we have found is that the radon levels in these premises are also substantially below the WHO level. We also take account of studies done by our tertiary institutions. Some recent surveys on radon release from building materials in Hong Kong have been conducted by the University of Hong Kong. These were published in Health Physics Module 67 Number 4, and the results are quite comparable to the results of the surveys conducted by the Government.
Public Officer Replying : SECRETARY FOR PLANNING AND LANDS
Madam President, as we know, everything contains radioactivity, including our bodies. Our bodies also contain traces of elements such as potassium-40 or carbon-14, and so we are all radioactive in a way. As Member said that building materials may contain traces of elements, from the air, we also get gamma rays and so forth. So radioactivity is all around us. But I do not think we need to be alarmed about that.
Member asking : LUI MING-WAH
主席,局長還未回答,如果建築材料是沒有輻射的話,那麼氡氣是從哪裏來呢?
Public Officer Replying : SECRETARY FOR PLANNING AND LANDS
Madam President, radon comes from radium, and some of the trace radium are contained in building materials. I am not saying that building materials do not contain any radioactive substances. In fact, what I am saying is that everything contains radioactive substances. People here in the Legislative Council contain radioactive substances, and we emit certain amount of radioactive substances all the time, except that the level is negligible and not harmful to health.
Member asking : CHOY SO-YUK
Madam President, part (c) of the main reply says the Government feels that it is not necessary to introduce legislative control on building materials, because survey results show that the existing materials do not contain high level of radiation. When saying that the existing materials do not contain high level of radiation, does the Secretary mean that all future construction materials will also be radioactive-free and safe? If there are new materials which are highly contaminated, how would the Government be able to stop people from using them; and how could the building concerned be decontaminated without having to cost a lot of money, or would it be necessary to have the whole building totally demolished?
Public Officer Replying : SECRETARY FOR PLANNING AND LANDS
Madam President, I think we really have to trust the good sense of our surveyors and architects in not using any highly radioactive substance to build our residences. And probably, this is not a cost-effective way of building houses anyway. But we would be looking out for reports around the world from tertiary institutions and so forth, so as to bring ourselves up-to-date on the latest findings about building materials, just to ensure that the specific activities of these materials would not cause any radioactive damage to the health of people in Hong Kong.
主席
:蔡素玉議員,你的補充質詢是否未獲答覆?
Member asking : CHOY SO-YUK
主席,局長只是回答政府會倚賴測量師,那麼政府如何確保測量師是有監察建築材料的輻射水平呢?
主席
:蔡議員,你在剛才的補充質詢中,有否問及政府如何確保不會採用輻射性高的物質作為建築材料?
蔡素玉議員
:主席,是有的。
Public Officer Replying : SECRETARY FOR PLANNING AND LANDS
Madam President, we have not resorted to testing every single building material, because it probably would be quite an inefficient way of doing things. What we have resorted to do is to test the well-being of the ambience that we are in. So we have been taking a holistic approach in testing the radon level in domestic premises, for example. This is the way that we will continue to take in testing the health effects that may have been imposed on us in the residences.
Public Officer Replying : SECRETARY FOR PLANNING AND LANDS
Madam President, I have also mentioned the studies conducted by the University of Hong Kong. They have looked at other different substances such as radium-226 and thorium-232. It is found that they are also in a range comparable to, for example, potassium-40 which is contained in our own body. So basically, there is no need to be alarmed about the different radioactive substances that are contained in different building materials commonly used in Hong Kong today.
Member asking : SHEK LAI-HIM, ABRAHAM
Madam President, to give us a level of comfort, would the Secretary please advise us on the level recommended by the WHO and also the result of surveys and studies about buildings done in Hong Kong?
Public Officer Replying : SECRETARY FOR PLANNING AND LANDS
Madam President, the WHO recommends that for anything which has a level of above 200 becquerel per gram, we should start taking remedial action. For most of the studies conducted in Hong Kong, it is found that most of the levels that we have attended are less than 70.
Public Officer Replying : SECRETARY FOR PLANNING AND LANDS
Madam President, Dr HO mentioned about granite. Granite or granite aggregate is quite commonly used in a lot of building materials. But in fact, granite contains no more than 1 becquerel per gram, which is very low. According to the Radiation Ordinance in Hong Kong, we do not define radioactive substance unless it has reached a level of 75 becquerel per gram. So I think using granite aggregates in building materials in Hong Kong is not a major concern. As I responded to an earlier question, when we have new materials or new designs coming in, I am sure that we can resort to the good sense of our builders and architects in using the proper materials.
主席
:何鍾泰議員,你的補充質詢是否未獲答覆?
Member asking : HO CHUNG-TAI, RAYMOND
主席,首先,我想指出局長所使用的單位錯了,不應是becquerel per gram,而是becquerel per cubic metre。至於局長未回答的部分為,自從環保署在10年前發出有關指引後,建築物在設計上有何改善?指引亦有說明,希望在設計上減少縫隙,以免地面或地庫有氡氣滲入,以及減少把岩石暴露於空氣中,盡量把岩石遮蓋等,這些都是在環保署的報告中提及的,我想知道建築物的設計有否根據指引進行呢?
Public Officer Replying : SECRETARY FOR PLANNING AND LANDS
Madam President, it is not wrong to say becquerel per gram, because we are talking about mass, rather than volume. In regard to the different measures which have been recommended, I am sure that all the architects and builders are quite aware of them. It is basically to improve ventilation in an enclosed space, which would be the most effective way to bring down the concentration level of radon, and I think architects would design buildings according to this sense. For a great deal of reinforced concrete structures, they would seek to apply some special plaster to seal the cracks, or avoid using a lot of spaces in basements and so forth. I think those are the common ways that builders would seek to reduce the level of radon which would be harmful to the health of human beings.
Public Officer Replying : SECRETARY FOR PLANNING AND LANDS
Madam President, I think I can assure Mr WONG that it is perfectly safe to spend a lot of time in this Chamber. As I mentioned earlier, granite contains no more than 1 becquerel per gram, and to be considered as radioactive under the Radiation Ordinance, the substance has to achieve a level of 75. So there is quite a huge order of magnitude between the two, and I think Members can be assured of that.