Use of construction materials with radioactive substances
Member asking : HO CHUNG-TAI, RAYMOND
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.
Member asking : HO CHUNG-TAI, RAYMOND
- 主席,非常感謝今天有3位局長出席回答我的質詢。環境保護署(“環保署”)在92-93年度曾向專業人士發出一項指引,編號為PN1/99,當中指出,當局在進行廣泛調查後,發覺氡氣會對人體有害,如會引致肺癌等,而新的傢俬亦可能會釋放出例如甲醛 (formaldehyde)等有害的氣體。局長在主體答覆第(一)部分中提及“已不時測量本港樓宇的氡氣量”,請問當中的“不時”究竟是指在何時進行測試,以及是由哪個部門負責?因為環保署的有關指引,只提及在10年前曾進行過有關的測試。
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.
Member asking : LUI MING-WAH
- 主席,主體答覆的第(一)部分提及,政府不認為有需要特別檢驗本港在過去3年落成的樓宇是否使用輻射性建築材料。如果輻射不是從建築材料而來,那麼請問政府,氡氣是從哪裏來,是從空氣還是其他物質而來呢?
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
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
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.
Member asking : WU KING-CHEONG, HENRY
- 主席,我亦同意政府所說,就此問題立例作出管制是有困難的。不過,我認為政府就這項質詢作出的回覆,可以說是沒有回答一樣。如果在立法會中使用一些技術性的詞語,我相信很多人也不會明白。請問局長可否使用一些較易明的詞語,例如主體答覆第(一)部分中提及本港樓宇內的氡氣量遠低於世界衛生組織建議......
Public Officer Replying : PRESIDENT
- 胡議員,很抱歉,我要打斷你的補充質詢。我認為在質詢時間中,議員是不應該指示政府官員如何作出回應的。請你直接提出補充質詢。
胡經昌議員
- :主席,我正是就這點提出補充質詢。請問局長可否以一些簡單、容易明白的資料作出解釋,讓我們不用花時間提出跟進質詢?(眾笑)
主席
- :胡議員,很抱歉,我不覺得你的補充質詢與主體質詢有任何關連。局長有權用自己的方式作答,我們是不能要求局長如何回答質詢的。
胡經昌議員
- :主席,我想舉出一個例子,讓局長參考;但如果主席認為沒有舉例的需要,我便不舉例了。
主席
Member asking : TANG SIU-TONG
- 主席,主體答覆中只提及氡氣,但正如何鍾泰議員提到,aldehyde亦會對人體健康有影響。請問除了氡氣之外,有否其他放射性元素存在於建築材料之中而又會影響人體健康的呢?
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.
Member asking : HO CHUNG-TAI, RAYMOND
- 主席,局長剛才沒有真正回應呂明華議員的補充質詢。我想指出,我所提及的環保署指引要求專業人士在設計上,盡量減少氡氣對健康造成的影響,而局長亦表示會這樣做。在設計上,花崗岩會釋出氡氣,而混凝土中含有花崗岩,所以也會有釋出氡氣的問題,傢俬中的木材亦會釋出甲醛氣體。局長要求或希望專業人士在設計上盡量減少有害氣體的濃度,而環保署的有關指引亦提出類似的要求,請問局長,在過去10年,自環保署發出了指引後,建築物在設計上有何改變呢?
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
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.
Member asking : WONG WANG-FAT, ANDREW
- 主席,我們都知道立法會大樓是一座花崗岩建築物,請問局長曾否測量這大樓內的氡氣量是否符合標準?我亦希望當局在進行測量之後,可向我們保證,我們在這裏進行會議是相當安全的。(眾笑)
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.
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