REALTY HARVEST LTD AND OTHER v. GOLD MARGIN DEVELOPMENT LTD AND ANOTHER

HCA 11197/98

IN THE HIGH COURT OF THE

HONG KONG SPECIAL ADMINISTRATIVE REGION

COURT OF FIRST INSTANCE

ACTION NO. 11197 OF 1998

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J U D G M E N T

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1. In this action, the plaintiffs claim against the 1st defendant in nuisance for the noise and vibration emitted from its machinery. The claim against the 2nd defendant is in breach of deed of mutual covenants.

The Background

2. The 1st plaintiff is the registered owner of the premises known as 2/F. Yue Fung Industrial Building situated at 35-43 Chai Wan Kok Street, Tsuen Wan, New Territories ("the plaintiffs' premises'). The 2nd and 3rd plaintiffs are respectively the tenant and sub-tenant of the 1st plaintiff in respect of the plaintiffs' premises.

3. The 2nd defendant is the registered owner of unit 12, 3/F. of the same Yue Fung Industrial Building ("the defendants' unit'). The 1st defendant has been the tenant of the defendants' unit since 2 March 1998. The defendants' unit is situated one floor above the plaintiffs' premises.

4. The 2nd plaintiff is a contractor in electrical installation work whereas the 3rd plaintiff is a supplier of materials for electrical installation work. Part of the plaintiffs' premises is used as godown and the other part as office. The office area is situated immediately below the defendants' unit.

5. The 2nd defendant is in the business of manufacturing woven labels by the use of 2 sets of weaving machine, each of about 10 feet in height.

6. It is the plaintiffs' case that since early March 1998, the employees of the 2nd and 3rd plaintiffs have heard loud noises and felt serious vibrations coming from the ceilings of the office area on the plaintiffs' premises. It is not in dispute that the noise and vibrations were generated by the 2 sets of weaving machine on the defendants' premises. The employees of the 2nd and 3rd plaintiffs were so affected and disturbed in their work that they had to be re-located to other area on the plaintiffs' premises.

7. The plaintiffs had since lodged complaints with the management authority of Yue Fung Building ("the Building"), Environmental Protection Department, Buildings Department and Labour Department. The management company was reluctant to take action to enforce the terms of the deed of mutual covenants of the Building ("the DMC") as requested by the plaintiffs. The Environmental Protection Department declined intervention on the basis that the matter complained of is not within the ambit of the existing legislation on control of noise pollution. As for the Buildings Department and the Labour Department, they also did not take up the complaints for they said the matter falls outside their scope of responsibilities.

8. The plaintiff says that in April 1998, additional false ceiling with insulation material had to be installed on the plaintiffs' premises to reduce the noise and vibration. It is also the defendants' case that they had in April and July 1998 and after consulting the supplier of the 2 sets of weaving machine, taken abatement action by placing rubber padding beneath the 2 sets of machinery to reduce the noise and vibration.

9. It is the plaintiffs' case that, throughout the period, the employees of the 2nd and 3rd plaintiffs had measured the noise levels with a digital sound level meter (exhibit P1) and recorded the readings. It is also not in dispute that on 22 July 1998, shortly after the Writ herein was issued, the 1st defendant brought 2 technicians to the plaintiffs' premises and in their presence, the noise level was measured and recorded. The readings were 60 db(A) for the office area and 70 db(A) for the godown area when one machine was running, and were 64 db(A) and 77 db(A) for the respective areas when both machines were operating.

10. On 5 August 1998, the 2nd defendant advised that better vibration isolators had been fitted to the machinery.

11. The plaintiffs commenced these proceedings in July 1998. In March 1999, the plaintiffs engaged expert to measure the level of sound and vibrations. A report was subsequently compiled. In June 1999, the 1st defendant also commissioned expert to examine the situation and a report was also compiled.

Issues

12. The defendants do not deny that the 2 weaving machines of the 1st defendant have produced noises and vibrations. They, however, deny that the noises and vibrations are excessive or such as to constitute nuisance and/or breach of the DMC. In particular, the defendants contend that regards must be paid to the fact that the Building is an industrial building situated in an industrial area. Accordingly, the major issue between the parties is whether the level of noise and vibration emitted from the defendant's premises is excessive or of such level as to constitute nuisance. For the 2nd defendant, there is a further issue of whether he has been in breach of his obligations under the DMC, even if the first issue is answered in the plaintiffs' favour.

The Evidence

(1) Witnesses of Facts

13. The plaintiffs had called 5 factual witnesses, who are all employees of the 2nd and/or 3rd plaintiffs. They are Mr Fung Kwai Kin, Mr Lai Ming, Mr Lo Ting, Jim, Miss Liu Yee Tung and Mr Chu Hon San, Sam. Mr Fung is the managing director of the 2nd plaintiff and Mr Lai is the administration manager. Both Mr Lo and Mr Chu are sales engineers whereas Miss Liu is an invoicing clerk. They all started working on the plaintiff's premises before March 1998. For Mr Fung and Mr Lai, they have been working on the plaintiff's premises since 1991 when the 2nd and 3rd plaintiffs moved in.

14. In March 1998, the working areas of Mr Lo, Mr Chu and Miss Liu were directly below the defendant's premises. They testified that one day in March 1998, they heard continuous loud noise coming through the ceiling of their working areas. They described the noise as being of low pitch or frequency and similar to that of an engine or of the piling machine. The witnesses also felt strong and continuous vibrations. They said that the vibrations were so strong that the air grilles and fluorescent light troughs in the false ceiling as well as their working desks shook. According to them, the disturbance was intolerable and they, except Miss Liu, had to move to another part of the plaintiff's premises where they have remained working since then. Miss Liu had not moved to another working area because her desk is at the fringe of the affected area and there is no alternative space available. The 3 witnesses said the noise and vibrations run for most part of their working hours with very brief stops occasionally. Their mood, concentration and efficiency are affected and they cannot communicate effectively with customers over the telephone. They testified that after attempts by the plaintiffs and defendants to reduce the noise and vibration, the level of disturbance was slightly reduced. The situation however fluctuates widely, and on the whole it remains intolerable. The witnesses all indicated that they do not wish to move back to work at the former office area.

15. Mr Fung and Mr Lai, although not working in the same area as the other witnesses, confirmed that they also heard the noise and experienced the vibrations when they went over to the affected area upon receiving complaints from the other witnesses. Mr Lai said that the affected area, which measures about 800 sq. ft., has not been used since March 1998. Both Mr Fung and Mr Lai, aided by Mr Chu, had measured and recorded the noise level by means of a digital sound level meter. The equipment is part of the working tools of the plaintiffs and was not specially acquired for the litigation. Mr Fung, who is a qualified engineer, is accustomed with the use of the meter as he has to use it in connection with clients' projects. As for Mr Lai and Mr Chu, they only learnt to use the meter in March 1998. Mr Lai said he had received instructions from Mr Fung on the use of the meter while Mr Chu said he had, in learning to operate the meter, read the instruction manual. It is Mr Lai's evidence that the meter is calibrated annually to ensure its accuracy.

16. The readings recorded by these witnesses during the month of March 1998 ranged between 68.5 db(A) and 80 db(A). In the month of July 1998, the readings were between 63 db(A) and 73.5 db(A). On 22 July 1998, after the 2nd defendant had arranged for rubber padding to be placed beneath 1 set of machine, the reading when only 1 set of machine was turned on was 60 db(A) for the office area and 70 db(A) for the godown area. When both sets of machine were turned on, the readings recorded were 64 db(A) and 77 db(A) for the respective areas. On 5 August 1998 after better quality rubber padding was fitted to the machines, the readings recorded were 65 db(A) and 70 db(A) for the office and godown. Between February and April 1999, the readings recorded fluctuated between 58 db(A) and 73 db(A).

17. All the 5 witnesses accepted that as the plaintiff's premises are located in an industrial building and the building is within an industrial area, the surroundings are bound to be noisy. They also agreed that there were noises even before March 1998. However, they all maintained that the noises and vibrations they have experienced since March 1998 are much more serious than what they had before that.

18. As for the 1st defendant, Mr Pang Pui Hung, one of its directors, had given evidence. He stated that, shortly after the 1st defendant started operation, the 1st defendant did receive complaints from the plaintiffs. He accepted that the 1st defendant's machinery did produce noise and vibration, but disagreed that they are excessive. Nevertheless, Mr Pang said, as good neighbours, the 1st defendant had twice added noise and vibration isolators to the 2 sets of machinery. According to Mr Pang, the 1st defendant had used all its best endeavours to reduce the noise and vibration and that it is unreasonable for the plaintiffs to expect an office environment in an industrial setting.

19. The 2nd defendant had also testified. He gave evidence that the defendant's premises were let to the 1st defendant for a term of 2 years. Upon the expiration in March 2000, the tenancy had been renewed for another 2 years. He said that he came to know of the plaintiffs' complaints in about July 1998. He then took steps to improve the situation, including arranging for and paying for the costs of adding better quality padding to the machinery in August 1998. The 2nd defendant pointed out that the Building has always been a noisy one because of the industrial undertakings situated inside it. He also said that the Building has a noisy surrounding. According to the 2nd defendant, no other occupants of the Building, save the plaintiffs, have ever complained about the noises and vibration coming from the 1st defendant's operation.

20. Much of the factual evidence in this case is not in dispute. The only areas of dispute turn on the events during the inspection by the plaintiffs' expert and the accuracy of the readings of the digital sound level meter recorded by the plaintiffs' witnesses.

21. It is the evidence of Mr Lai that when the plaintiffs' expert carried out the inspection on 8 March 1999, Mr Fung had requested the persons in charge of the 1st defendant to turn on both sets of machinery, but the request was declined. Hence, the inspection was conducted with only 1 set of machine being turned on. The plaintiffs' expert, Mr Sam Tsoi, confirmed this in his report and evidence. When Mr Pang gave evidence, he said that because there was no work, both sets of machine were not in operation when the plaintiffs' expert came. It is Mr Pang's evidence that the plaintiffs only requested for one set of machine to be turned on and no one had ever asked for both sets of machine to be operated.

22. On this point, I prefer the evidence of the plaintiffs' witnesses to that of Mr Pang. Mr Pang was contradicting himself when he said the 2 machines were not under operation during the inspection because there was no work when it is also his evidence that March is the peak season for the 1st defendant's business. It is to be noted that neither Mr Lai nor Mr Tsoi was cross-examined on this point. Mr Pang did not mention in his witness statement that the reason for running only one set of machine during the inspection was as what he testified in court. In my view, it is inherently improbable that Mr Tsoi would not have asked for both sets of machine to be turned on during his inspection, having regard to the purpose of his visit and the meticulous way in which he carried out the inspection and testing.

23. As to the noise level measured and recorded by Mr Fung, Mr Lai and Mr Chu of the plaintiffs, the defendants' challenge is twofold. First, it was said that the measurement was not carried out in the presence of independent witnesses. Secondly, the reliability of the digital meter was doubted on the basis that it was not calibrated on each occasion when it was used.

24. For my part, I do not consider the fact that the absence of the so-called independent witnesses is per se of significance. It has not been suggested that the plaintiffs' witnesses are untruthful in their evidence or have any reason to fabricate or falsely report the readings. As a matter of fact, all the plaintiffs' witnesses strike me as honest and straightforward witnesses. I do not believe that they would exaggerate or distort the readings. The witnesses had been cross-examined on their familiarity with the use of the digital meter. I have no doubt that Mr Fung is well familiar with the operation of the meter as he had to use it regularly in his work. In the case of Mr Chu, I do not think that, being an assistant engineer, he would have any difficulty understanding the operation manual and handling the meter. As for Mr Lai, I also accept his evidence that he knew how to operate the meter correctly, having been trained by Mr Fung.

25. On the question of calibration, Mr Lai's evidence clearly shows that the digital meter in question was subject to annual calibrations. The relevant certificates had also been produced. The calibration results show that the meter operated within the manufacturer's specification. The plaintiffs, however, accepted that, because the plaintiffs do not have the calibrator, the meter was not calibrated every time it was used. I accept that, on that basis, it is open to doubt whether the readings recorded are absolutely accurate and without marginal error. The readings recorded ought therefore to be approached with caution.

(2) Expert witnesses

26. Both the plaintiffs and the 1st defendant had commissioned experts to test the level of noise and vibrations emitted by the 2 sets of machine. For the plaintiffs, they had engaged the firm called Arup Acoustics. Mr Sam Tsoi of the firm, who was in charge of the measurement and analysis, had compiled a report and had also given evidence in Court. As for the 1st defendant, the firm of Daniel Chan & Associates was engaged. Dr Tony Chan of the firm, who carried out the inspection and took the measurement at the plaintiffs' premises, compiled the expert report. Dr Chan, however, was not called to testify. The expert witness called by the 1st defendant is the proprietor of the firm, Professor Daniel Chan, who had endorsed and approved the expert report.

27. Mr Tsoi is a chartered engineer and holds academic qualifications in relation to vibration and noise controls. Since 1995, he has been leading the Hong Kong office of Arup Acoustics, a specialist group within Ove Arup & Partners Hong Kong. According to the curriculum vitae provided by him, Mr Tsoi has extensive experience in the design, manufacture and installation of noise control treatment and assessment projects, including the new airport at Chek Lap Kok and other projects locally and overseas. Counsel for the 1st defendant had indicated that the competence of Mr Tsoi as an expert witness was not challenged. Despite that, in examining her own expert, Professor Chan, she endeavoured to lead evidence that Mr Tsoi had sought to become a fellow of the Hong Kong Institute of Acoustics but failed. That in my view is both inappropriate and irrelevant, given that the status and competence of Mr Tsoi as an expert is not disputed. At any rate, from the qualifications and working experience of Mr Tsoi and judging from his evidence in Court, I have no hesitation in accepting him as an expert competent and knowledgeable in the areas of noise and vibration assessment and controls.

28. In the case of Professor Chan, he is the managing director of Daniel Chan & Associates and also a part-time associate professor with the department of architecture of the Chinese University of Hong Kong. He has been involved with work on environmental noise pollution and building services in the past 20 years and has issued publications and given presentations on these areas. Similar to Mr Tsoi, I am prepared to accept Professor as an expert witness.

29. According to Mr Tsoi, he, together with 2 staff members of his firm, went to the plaintiffs' and defendant's premises on 8 March 1999 to carry out measurement of the noise and vibration levels. He gave an account of the equipments they brought along on the occasion and also explained the procedure and steps adopted to check the equipment and carry out the measurement. The results recorded on the equipment were produced as attachments to his report.

30. In the case of Professor Chan, as previously mentioned, he did not attend the premises in question. According to him, he designed the methodology and specified the raw data to be collected. He then instructed his assistants, including Dr Tony Chan, about the measurement and tests to be done. His assistants made the first visit on 22 June 1999. That however was an aborted attempt because it was discovered afterwards that a wire of one of the equipments was broken. The second visit was made on 30 June 1999. Professor Chan also described the equipments used, but, as he was not involved in the process of taking measurement, he was not in a position to describe the procedure and steps adopted by his assistants. The results of the measurements were either recorded by digital recorder or noted down by his assistants. Analysis on the data collected was then carried out and the report was compiled.

31. Counsel for the plaintiff had complained that Dr Tony Chan was not called and not all the raw data he collected was available for the purpose of verification. No explanation had been advanced as to why Dr Tony Chan was not called. I agree that it is unusual not to call the person responsible for the measurement and compilation of the report. It is also unsatisfactory in that those parts of the expert report on site observations and the process of taking measurements become hearsay, since Professor Chan was not present at the inspection. The Court is in fact being asked to infer from Professor Chan's evidence, namely, his assistants had been trained and fully instructed, that the equipment had been properly operated, the measurements correctly carried out and the readings accurately recorded. That is clearly inappropriate. And the Court is also clearly in no position to draw such inference.

32. In my view, no weight can be placed on the part of the defendant's expert report dealing with site observation, as that is plainly hearsay. As to the results of the measurements contained in the report, little weight can be attached to it, as their reliability has not been properly proved.

33. The main point of contest between the parties' 2 experts, however, does not rest with the results of the measurements, but with the standards or methods of assessment to be adopted for the purpose of determining whether the noise and vibration level is excessive or acceptable. In assessing the noise level, Mr Tsoi had applied the British Standard BS 4142: 1997 ("BS4142"). BS4142 is a method for determining the level of a noise of an industrial nature by assessing whether the noise in question is likely to give rise to complaints by people living in the vicinity. This method involves measuring the background noise level and the noise level after the noise in question was added to the background noise, and then calculating the difference between these 2 noise levels. Corrections may have to be done to the difference ascertained by adding certain weightings where the noise in question carries certain characteristics. The difference thus established will then be used to assess the likelihood of complaints based on the table set out in BS4142.

34. In the present case, from the measurements made at 5 locations on the plaintiffs' premises, the difference between the background noise level and the noise level when one machine was turned on ranges between 9dbB to 14dbB. As Mr Tsoi considered the nature of the noise omplained of was of fast repeated cycles with tonal and impulsive characteristics, he therefore followed the recommendations of BS4142 and added a 5dbB weighting to the difference. The difference thus established is therefore between 14dbB and 19dbB. This falls within the "complaints likely" category under BS4142, which is defined as "a reasonable person when exposed to such noise level and/or characteristics would be dissatisfied or even annoyed, and this will probably lead to a complaint".

35. Professor Chan, on the other hand, had chosen speech intelligibility as the factor for assessment. He referred to the International Standard Organization (ISO) technical report TR3352-1974 ("ISO Report"), which prescribes a survey method for assessing the influence of noise on intelligibility of speech in direct communication. Under this method, the band pressure levels in the 4 octave bands whose centre frequencies are 500, 1000, 2000 and 4000 Hz are measured. The average value of these 4 octave bands will give the level of the disturbing noise. The level, known as the speech interference level, is then judged by a table which sets out the maximum distance at which normal conversation is considered to be satisfactorily intelligible, and that at which conversation at a raised voice is considered to be satisfactorily intelligible.

36. In this case, Professor Chan's assistants measured the band pressure levels in the 3 octave bands centered on 500, 1000 and 2000 Hz at 3 chosen locations on the plaintiffs' premises when, firstly, only one machine was turned on and, secondly, when both machines were operating. The speech interference level thus calculated was 50.8db, which is right within the acceptable range of the table in the ISO Report. Professor Chan therefore concluded that the noise level was acceptable since face to face communication is possible.

37. As for vibration assessment, Mr Tsoi adopted the British Standard BS 6472: 1992 ("BS6472") which is a standard providing guidance on human response to building vibration. The major feature of BS6742 is that it takes into account the effect of duration in assessing the likely human response. The assessment method involves measuring the vibration dose value (VDV) or the r.m.s. (i.e. root mean square) value of the frequency-weighed acceleration. Based on the measurements, the estimated vibration dose value (eVDV) is then calculated, which involves the use of a constant or multiplying factor. The constant or multiplying factor is determined by reference to the time of the day and the duration of exposure to continuous vibration as well as the use made of the building, whether it is a workshop or office and so on. The result is then judged in accordance with the prescribed complaint assessment-rating table.

38. Based on this method, the calculated eVDV for 3 of the 5 chosen locations on the plaintiffs' premises exceed the recommended limit for offices under BD6742. For one of these 3 locations, the result falls within the "adverse comment probable" category of the assessment-rating table. "Adverse comment probable" is defined as "a reasonable person when exposed to such vibration levels would be dissatisfied or even annoyed, and this will probably lead to a possible complaint". As for the other 2 locations, they fall within the "adverse comment possible" category of the assessment-rating table. "Adverse comment possible" is defined as "a reasonable person when exposed to such vibration levels would probably be dissatisfied or even annoyed, and this leads to a possible complaint".

39. As for Professor Chan, he preferred to use what he referred to as the European Commission Directive ("EC Directive") published in 1993 as the criteria for assessing the vibration. According to Professor Chan, the EC Directive provides criteria on the risk to health and safety of workers resulting from their exposure to vibration. It involves measuring the r.m.s. acceleration level and comparing it to 2 criteria called "threshold level" and "ceiling level". Vibration above the threshold level (i.e. 0.25m/s2) may cause back morbidity and trauma of the spine as well as severe discomfort. As for vibration above the ceiling level (i.e. 0.7 m/s2), it is said to be dangerous and systematic health surveillance is required.

40. The r.m.s. acceleration values obtained by Professor Chan's assistants at the 3 chosen locations on the plaintiff's premises produce a level below 0.25 m/s2. On this basis, Professor Chan concluded that the overall vibration level was acceptable.

41. In deciding which of the 2 expert opinions to adopt, I have regard not only to the reports prepared or endorsed by them and their oral testimony, but also to the contents of the authorities they relied upon, namely, the 2 British Standards and ISO Reports. I am of the view that the evidence and methods adopted by Mr Tsoi is to be preferred to those of Professor Chan.

42. In the area of noise assessment, BS4142 clearly prescribes a more relevant and appropriate standard and method than the speech intelligibility or interference criteria set by the ISO Report. Firstly, BS4142 relates to an industrial setting and noise of an industrial nature. Secondly, the criteria contained in the ISO Report is only applicable to face to face communication and not to telephone conversation. It therefore does not address one of the major complaints of the plaintiffs' employees, namely, the noise complained of have prevented effective telephone communications. Thirdly, the ISO Report published in 1974 contains the following opening remarks : "It was decided to publish the document in the form of a Technical Report as this is a subject that cannot yet be considered as suitable for an International Standard. The subject is still under study and it may be found necessary to make changes in the levels of mean speech power in the future." Further in the Introduction section, it says that the mean speech power levels "may be subject to future modifications according to the results of the studies that are in the programme of work of WG 12 of ISO/TC43/SC 1". Plainly, the method or criteria described in the ISO Report was still being developed after 1974. In answer to my queries, Professor Chan stated that he was not aware of the subsequent development. Purely on this point alone, it would not be appropriate or safe to rely on the ISO Report when its subsequent development is unknown. By contrast, BS4142, being a third revised edition published in 1997, must be more reliable.

43. Even if the Court is to adopt the criteria prescribed by the ISO Report, the reliability of the results and the related conclusions contained in the report endorsed by Professor Chan are open to doubts. This is because instead of measuring the band pressure levels in the 4 octave bands prescribed in the ISO Report, only the band pressure levels in 3 of the octave bands had been measured. Professor Chan explained that this was because 4000 Hz is not among the common bands for intelligibility, and that this octave band was included only for cautious sake. That may well be the case, but if we were to adopt the ISO Report as an assessment guideline, we would have to follow fully the prescribed method of measurement. It is to be noted that in the ISO report, speech interference level is represented by the average values of the 4 recommended octave bands. The average figure of 3 of the recommended octave bands therefore cannot give the speech interference level for the purpose of the assessment. Indeed, if the 4000 Hz octave band is included for cautious sake, it is all the more important that measurement in this octave band be obtained so as to ensure that the average value is accurate.

44. Apart from the ISO Report, the expert report endorsed by Professor Chan also made reference to the level of 85 db(A) prescribed in section 2 of the Factories and Industrial Undertakings (Noise at Work) Regulation, Cap. 59. As counsel for the plaintiffs observed, this statutory level has no application here in that it is a standard to govern the duties of proprietors of factories and industrial undertakings vis-à-vis their employees. It is also a standard for criminal prosecution under the legislation.

45. Professor Chan had commented in his oral evidence that he considered BS4142 unsuitable in that it had not taken into account the local conditions. Professor Chan, however, did not elaborate on what aspects of the local conditions have rendered the British standard inapplicable. This comment is therefore of no assistance to the Court. Professor Chan also observed that the terms of "complaint likely" and "probably" too imprecise. But as he repeatedly emphasized in his evidence, we are not dealing with an absolute science. Relativity and certain degree of subjectivity are therefore inevitable in assessing the levels of noise and vibration. Professor Chan is also critical of the addition of a 5dbB weighting by Mr Tsoi to reflect certain characteristics of the noise of the machines. He considered it too subjective. The method of adding weighting to reflect the characteristics of the noise under investigation is not unique to BS4142. As Mr Tsoi's report shows, the Technical Memorandum published by the Environmental Protection Department in connection with the Noise Control Ordinance also recommends the adoption of this correction method in appropriate cases. No doubt, the decision whether to add any weighting is a subjective one, but it is the subjective decision of an expert in the field. In the present case, Mr Tsoi had personally visited the premises in question and experienced the noise complained of. In his expert opinion, he considered the noise tonal and impulsive in nature. There is thus no basis to doubt his decision to add the weighting recommended by BS4142.

46. In the area of vibration assessment, I am also of the view that BS6472 is an appropriate means of assessment. In the first place, it gives a general standard for ascertaining human response to vibrations in a building. Unlike, for instance, the EC Directive or another standard referred to by Professor Chan, i.e. ISO2631, it is not confined to specific category of people and situations. In the case of the EC Directive, it is reportedly dealing with assessing hazards and injuries to the health of workers, hence addressing the issue of industrial safety. As for ISO2631, it is apparent from the report itself that it is dealing with the health and comfort of passengers travelling on public transportation. Further, by taking into account such elements as the nature of the location in question and the duration of the exposure to vibration, the assessment method described by BS6472 is more comprehensive.

47. Professor Chan had criticized BS6472 as being too complicated. I agree that, because of the employment of various technical terms and measuring units, the text of BS6472 is not easy to read. However, the method and the theories involved are not difficult to apply or understand. The former is essentially a matter of arithmetic calculations. Professor Chan also questioned the use of vibration dose value (VDV) on the basis that it ignores frequency. This cannot be right because the publication on BS6472 clearly states that "the vibration dose value is given by the fourth root of the integral of the fourth power of the acceleration after it has been frequency-weighted": see Appendix B. Frequency is therefore a component and element taken into account by BS6472.

48. On the other hand, I have reservations on the current status of the EC Directive much relied on by Professor Chan as an internationally accepted standard. Mr Tsoi testified that the EC Directive first appeared in a draft form, and he is not aware of a finalized version being produced. Professor Chan also accepted that he came across it when it was circulated as a draft in 1993 for comments. He is unable to say whether it has eventually been approved and adopted by the European Commission or whether it remains in draft form. There is one curious feature about this EC Directive. It is that, despite requests from the plaintiffs' solicitors, the 1st defendant has not provided nor produced in evidence a copy of the EC Directive. Professor Chan said that he had not been able to trace the full text of the EC Directive, but he had supplied an extract of it to the 1st defendant's solicitors. I find this all very strange. According to Professor Chan, he had on a number of occasions used this EC Directive for other cases or projects. One would therefore expect a copy of it to be readily available to him. One would also expect him to be well familiar with its development, including whether it has been finalized and passed by the European Commission. Given the state of the evidence, there must be a grave doubt as to whether the EC Directive described in the 1st defendant's expert report can be regarded as affording an internationally recognized or approved standard for assessing the effect of vibrations.

49. Even assuming that the EC Directive is an internationally approved standard, its applicability to the present case is not without doubt. As mentioned above, it is a standard reportedly dealing with industrial safety. That understandably is not quite the same as the standard for assessing the disturbance and discomfort caused by vibration in a building to its occupants.

50. In support of his use of the standard in the EC Directive, Professor Chan referred to an earlier decision of Deputy Judge Yeung (as he then was) in the case of Samfit Limited v. Hoi Tung Computer Label Industrial Company Limited (unreported) HCA10291 of 1993. Professor Chan suggested that the Court in that case had approved the threshold level of 0.25m/s² as the criteria for evaluating whether vibration was excessive. It appears from the judgment that Professor Chan was one of the 2 experts for the plaintiff in that action. Both he and the other plaintiff's expert were of the opinion that the noise and vibration were excessive and should be reduced. Professor Chan was said to have considered that the vibration could be reduced to 0.25m/s² while the defendant's expert had reservation about it. The Judge took the view that some allowance should be given to the defendant, and he therefore granted an injunction restraining the operation of the defendant's machines unless the vibration level be reduced to no more than 0.3m/s².

51. I do not read the judgment of the Deputy Judge as approving or establishing 0.25m/s² as the standard for determining whether any vibration is excessive or otherwise. It does not appear from the judgment that the Deputy Judge had been called upon to adjudicate on which standards should be adopted for vibration assessment. The judgment therefore cannot be regarded as approving the adoption of the EC Directive.

52. It is also of interest to note that in the Samfit Limited case, Professor Chan had in his report set out 3 vibration limits based on an exposure time of 8 hours per day, and 0.25m/s² is but one of them. This shows that he had also acknowledged the relevance and importance of the duration of exposure to vibrations, which is a major feature of BS6472. As a matter of fact, Professor Chan had in his report in the Samfit Limited case placed reliance on the standard in BS6472, which in his words "is frequency dependent": see pp.7-8 of the judgment.

53. Having regard to the matters aforesaid, I am of the conclusion that the evidence and views expressed by Mr Tsoi is to be adopted as the basis for determining whether the gravity of the level of noise and vibration in question.

Nuisance

54. There can be no doubt that noise and/or vibration can constitute the tort of nuisance. The question is whether the noise and/or vibration amount to a material interference with ordinary comfort. This is a question of degree to be answered by reference to the facts of each case: per Lord Halsbury in Colls v. Home and Colonial Stores [1904] A.C. 179, at 185. It also involves balancing the right of a defendant to use his property for his own lawful purpose and the right of the plaintiff to the undisturbed enjoyment of his property.

55. On the basis of Mr Tsoi's findings and analysis, the noise detected at the plaintiffs' premises is of a level that a reasonable man will be dissatisfied or annoyed. This is so even when only one machine is in operation. Similarly, in relation to the vibration detected at the godown area of the plaintiffs' premises, the level is such that a reasonable man will be dissatisfied or annoyed. As for the office area directly below the defendant's premises, the vibration detected is one that a reasonable man will probably be dissatisfied or annoyed. Again, this is when only one of the machines is in operation. Accordingly, the combined effect of the noise and vibration when both sets of machine are operated is clearly substantial and serious as will materially interfere with the work efficiency and ordinary comfort of the people working on the plaintiff's premises.

56. Indeed, it is the evidence of the plaintiffs' employees that they found the noise and vibration intolerable, and that their mood, concentration and efficiency have been adversely affected. There is also the evidence that the 2nd and 3rd plaintiffs had to provide earmuffs for their staff when they work in the godown areas. It is evident from the evidence of the plaintiffs' employees and expert that the level of noise and vibration is serious and excessive.

57. In this case, the defendants argued heavily that because the Building and its surroundings are noisy, the noise and vibration arising from the operation of the 1st defendant's machines should not be regarded as exceeding the reasonably acceptable level.

58. In the case of Rushmer v. Polsue & Alfieri Limited [1906] 1 Ch. 234 (approved by the House of Lords in [1907] A.C. 121), Cozens-Hardy L.J. rejected the argument that a resident of a district specially devoted to a particular trade cannot complained of nuisance by noise caused by the carrying on of a branch of that trade short of proving carelessness and unreasonable use. His Lordship was of the opinion that a resident in a noisy district must put up with a certain amount of noise, and the standard of ordinary comfort will differ according to the situation of the property and the class of people who inhabit it. The approach is therefore whether "the addition of a fresh noise caused by the defendant's works may be so substantial as to create a legal nuisance". But "if a substantial addition is found as a fact in any particular case, it is no answer to say that the neighbourhood is noisy": at pp.250-251.

59. Accordingly, the facts that the Building is an industrial building with noisy undertakings and that it is situated in a busy industrial area do not per se prevent the plaintiffs from having a cause of action. However, these are relevant considerations in deciding whether the situation gives rise to a claim. The plaintiffs will have no cause of action unless they can establish that the noise and vibrations generated by the1st defendant's operation have brought substantial additional noise and vibrations over and above those already in existence before the 1st defendant commenced its operation in March 1998.

60. In this regard, there is the evidence of the plaintiffs' employees that the noise and vibration introduced by the 1st defendant are far in excess of what they had experienced from the other undertakings in the Building and from the surroundings of the Building before March 1998. The 2nd defendant had vaguely suggested that the plaintiffs had previously complained of noise from another undertaking in the Building, but the plaintiffs' witnesses had denied that. No evidence had been introduced to make good this suggestion. There is no evidence to contradict the evidence of the plaintiffs' employees that the noise level prior to March 1998 was not as serious as that generated by the 1st defendant's operation. This demonstrates that the 1st defendant's operation have added fresh noise and vibration that are substantial in nature. That being the case, it is no defence to say that the plaintiffs' premises is situated in a noisy building with noisy surrounding.

61. The defendants have also argued that the Building is an industrial building and is not intended to be used as office premises. It is therefore unreasonable for the plaintiffs to expect an office setting in an industrial setting. In the Samfit Limited case (at pp.12-14), Deputy Judge Yeung, in rejecting an argument that using an industrial unit as an office is a breach of the occupation permit, observed that it is a common feature in industrial buildings in Hong Kong that part of the unit is being used as an office. The Deputy Judge further pointed out that it matters not whether the premises are sued as a warehouse, an office or a factory because the occupants cannot be involuntarily subject to excessive noise and vibration.

62. Having regard to the evidence in this case, I have come to the conclusion that the noise and vibration produced by the 1st defendant's machines have exceeded the reasonably acceptable limit having regard to all the circumstances of the case. They have interfered with the proper enjoyment by the plaintiffs of their premises. The 1st defendant's wrongful acts therefore constitute an actionable nuisance. Accordingly, the 1st defendant is liable to the plaintiffs in nuisance.

Breach of DMC

63. Paragraph 9 of Section IV of the DMC provides, inter alia, that no owner shall do or permit or suffer to be done and each owner will take all possible steps to prevent his tenants, occupiers or licensees from doing any act, deed, matter or thing which in any way interferes with or affects or which is likely to interfere with or affect the proper use and enjoyment of the Building or any part or parts thereof by other owners or occupiers of the Building.

64. Paragraph 33 of the same section further provides, inter alia, that no owner shall do anything in any unit whereby excessive noise or vibration or other form of disturbance is created to the detriment to other persons in the Building, and that in the event of a breach thereto by the owner, such owner shall immediately rectify the default and make good any damage caused to the occupants of the Building.

65. Having found that the noise and vibrations emitted from the 1st defendant's machines are excessive and have affected the proper use and enjoyment of the plaintiffs' premises, the question that arises for determination in relation to the 2nd defendant is whether the 2nd defendant has permitted or suffered to be done and whether he has take all possible steps to prevent the 1st defendant from emitting the noise and vibration complained of.

66. The undisputed evidence shows that the 2nd defendant had as early as July 1998 taken step to try to reduce the level of noise and vibration from the 1st defendant's machines. The 2nd defendant therefore argued that he had done all that he could possibly do. Counsel for the plaintiffs however submitted that the 2nd defendant has not taken all possible steps in that the steps he took did not produce the desired or required results of isolating and reducing the noise and vibration. It was submitted that the 2nd defendant should have imposed conditions on the manner in which the 1st defendant operated the machines.

67. I agree that the 2nd defendant has not been totally inactive or irresponsible in tackling the nuisance created by the 1st defendant's operation. I, however, agree with counsel for the plaintiff that the 2nd defendant has not taken all possible steps to prevent the 1st defendant from continuing with the nuisance. It is the 2nd defendant's evidence that he had recently renewed the 1st defendant's tenancy. He could have and should have ensured that the noise and vibration emitting from the 1st defendant's machines be brought within the acceptable level before agreeing to the renewal. Alternatively, as counsel for the plaintiff suggested, he could have made this as a covenant in the new tenancy agreement.

68. In the circumstances, the 2nd defendant should be held liable to the plaintiffs in breach of the DMC.

The Relief

69. In the Amended Statement of Claim, the plaintiffs seek against the 1st defendant a prohibitive injunction and damages for nuisance. As for the 2nd defendant, the plaintiffs seek a mandatory injunction and also damages for breach of the DMC.

(1) Injunctions

70. Counsel for the 1st defendant submitted that no injunction should be made against the 1st defendant because it would put an end to the 1st defendant's business and create serious hardship to him.

71. In Shelfer v. City of London Electric Lighting Company and Meux's Brewery Company v. City of London Electric Lighting Company [1894] 1 Ch. 287, the judge, having found that the defendants had created a continuing nuisance, held that the plaintiffs were entitled to relief by way of damages, but not of injunction. On the plaintiffs' appeals against the refusal of injunction, both Lord Halsbury and Lindley L.J. in their judgments approved the principle that once a plaintiff has established his right or the fact of violation, unless there is something special in the case, he is entitled as of course to an injunction to prevent the recurrence of the violation.

72. As to what constitutes special circumstances, A.L. Smith L.J. said (at p.322) that :

"It may be stated as a good working rule that damages may be given in substitution for an injunction in cases where there are found in combination the four following requirements, viz., where the injury to the plaintiff's legal rights is (1) small, (2) capable of being estimated in money, (3) can be adequately compensated by a small money payment, and (4) where the case is one in which it would be oppressive to the defendant to grant an injunction."

73. It is further observed by Lindley L.J. (at p.313) that it is for the defendant to prove that it is impossible for him to carry on his business without creating a nuisance.

74. In this case, despite the submission of counsel, the 1st defendant has adduced no evidence to support the assertion that it would encounter hardship if an injunction is granted against it. There is no evidence showing that the 1st defendant cannot operate its business if it is retrained from producing excessive noise and vibration. Quite the contrary, Professor Chan had, in the report endorsed by him, made proposals as to how the situation can be improved. Indeed, it is Professor Chan's evidence that improvement can always be made to reduce the noise and vibration even when the level is already within the acceptable limit.

75. In my view, there is nothing special in the circumstances of this case as to warrant the refusal of the injunction sought against the 1st defendant.

76. The same is true of the injunction sought against the 2nd defendant. Although the injunction sought is mandatory in nature, that is justified by the fact that the 2nd defendant is found to be in breach of a restrictive covenant in the DMC.

77. In connection with the precise terms of the injunction orders, counsel for the plaintiffs submitted that the defendants should be asked to reduce the noise level to no more than 10 db(B) above the background noise level and the vibration level to not more than 0.4m/s 1.75. These are the acceptable standards under BS4142 and 6472. Counsel also suggested that the restrictions be confined to the normal working house on working days, and that the defendants be allowed a period of 2 months to meet these prescribed standards. I agree that these terms are appropriate.

(2) Damages

78. The plaintiffs had not particularized the damages sought in the pleading. In his opening submission, counsel for the plaintiffs indicated that the damages claimed relate to (a) the costs of installing additional false ceiling in the amount of $13000, and (b) the loss of use of part of the plaintiffs' premises. Counsel expressly stated that the plaintiffs do not peruse a claim in loss of amenities.

79. On the claim relating to the costs of installing an addition false ceiling, I have no hesitation that the evidence establishes that the 2nd plaintiff had incurred the expenses and that this is as a direct result of the nuisance created by the 1st defendant and/or the breach of the DMC by the 2nd defendant. The 2nd plaintiff is therefore entitled to recover the sum of $13,000 against the 1st and 2nd defendants by way of damages.

80. As to the claim for loss of use of the part of the office area on the plaintiffs' premises, I agree that this is a head of loss that may be recovered. I am, however, of the view that the evidence adduced in this case is insufficient to arrive at a proper assessment of the quantum. There is evidence from Mr Lai that the office where Mr Lo and Mr Chu used to work is about 800 sq. ft. Mr Lai further testified that the 3rd plaintiff had been paying $120,000 per month to the 2nd defendant as rent for the use of the plaintiffs' premises. It is unclear from the evidence as to what is the total size of the areas of the plaintiffs' premises that are sub-let to the 3rd plaintiff. Without knowing this, it is not possible to work out what portion of the monthly rental represents the area where the 3rd plaintiff's employees used to work. Further, although it has been said by Mr Lai that the area remained unoccupied because Mr Lo and Mr Chu refused to move back to their previous working area, the evidence does not show that the area has been left completely vacant and not used, for example, for storing files and records. It is the evidence of Mr Lo that there are filing cabinets and shelves within this area for holding customers' documents and records, and that because he is now working from a different area, he finds it inconvenient and difficult at times to lay hands on these documents and records.

81. Having regard to the state of evidence on the size and present use or otherwise of the affected area, I am not prepared to award damages for loss of use of this part of the plaintiffs' premises.

Conclusion

82. For the reasons aforesaid, there will be judgment for all the plaintiffs :

(1) For an order restraining the 1st defendant by itself, its servants or agents or otherwise howsoever from producing and emitting noises whose level is more than 10 db(B) above the background noise level and vibrations whose level exceeds 0.4m/s 1.75 between the hours of 9a.m. and 5p.m. on Mondays to Saturdays, but excluding holidays.

(2) For an order requiring the 2nd defendant to forthwith take steps to prevent the emission from the defendant's premises between the hours of 9a.m. and 5p.m. on Mondays to Saturdays, but excluding holidays, noises whose level is more than 10 db(B) above the background noise level and vibrations whose level exceeds 0.4m/s 1.75.

83. In order that the defendants can arrange for and carry out the necessary improvement work, the injunction orders are not to take effect until after 2 months from the date of the handing down of this Judgment. There is liberty to the parties to apply in connection with the implementation of the injunction orders.

84. There will also be judgment for the 2nd plaintiff against the 1st and/or 2nd defendants for damages in the sum of $13,000.

85. I also make an order nisi that the plaintiffs shall have the costs of the action to be taxed if not agreed. The order nisi to be made absolute after the expiration of 14 days from the handing down of this Judgment.