Executive Summary : Agreement No. CE 14/95
Consultancy Study on Indoor Air Pollution
in Offices and Public Places in Hong Kong
Panel on Environmental Affairs
Control of Indoor Air PollutionPURPOSE
This paper presents the findings and recommendations of the consultancy study commissioned by the Environmental Protection Department (EPD) on the indoor air pollution in offices and public places in Hong Kong, and proposes a framework and way forward for the control of indoor air pollution.
2. In the Second Review of the "1989 White Paper on Pollution in Hong Kong" in November 1993, the Government recognised the existence of potential health risk and problems associated with indoor air pollution. To address this issue, the EPD commissioned a consultancy study on "Indoor Air Pollution in Offices and Public Places" (the Study) in October 1995. A Steering Group, chaired by EPD, was formed to manage the consultancy study. Other members included representatives from the Planning, Environment and Lands Bureau, Architectural Services Department, Electrical and Mechanical Services Department, Labour Department, and Department of Health.
3. The Study aimed to characterise and quantify the indoor air pollution in office premises and selected public places in Hong Kong, assess the causes of the pollution problems, and recommend suitable control strategies. It comprised (a) questionnaire survey; (b) field sampling and analysis; (c) statistical analysis of the results; and (d) study on the practice of other countries. The Study was completed in September 1997. The Executive Summary of the Study is attached in Annex I
FINDINGS OF THE STUDY AND PROPOSED CONTROL OPTIONS
4. The Study has found that indoor air pollution in Hong Kong is very similar to that of other developed countries. About one-third of the occupants surveyed were dissatisfied with the indoor air quality (IAQ) of their respective buildings. Their perception of indoor air quality was found to have significant correlation with the actual measurement results including temperature, humidity, air change per hour, and levels of major air pollutants. Occasional high levels of pollutants such as carbon dioxide which exceeded internationally accepted guidelines were measured in some offices and public places. They were mainly caused by high occupancy density and inadequate ventilation.
5. The Study recognised that the approach adopted so far to control indoor air quality in Hong Kong is through implementing a series of ordinances and regulations which spread over a number of government departments. These statutory provisions can indirectly exert some controls on indoor air quality such as establishing basic ventilation requirements, imposing import and/or sale ban on certain products, and specifying designated "no smoking area" etc. A summary of responsibilities of government departments relevant to indoor air quality is given in Table 3 of Annex I.
6. The Occupational Safety and Health Ordinance enforced by Labour Department covers all workplaces including office premises, however it only covers employees. Occupational Exposure Limits are adopted by Labour Department to protect the health of employees. Whilst certain public places like cinemas and restaurants are under licensing control of existing legislation, there is no specific legislation on the control of indoor air quality in such other public places as shopping mall, karaoke, and gymnasium etc. This means that there is no enforcement body to take up complaint cases of such nature in Hong Kong at present.
7. The Study recommended that a more comprehensive management scheme with different implementation options for further consideration, and an inter-departmental Indoor Air Quality Management Group should be set up to co-ordinate the development on the control of indoor air quality. In the interim, a draft Code of Practice has been prepared by the consultant. This gives a set of indoor air quality objectives and good practices, and should be adopted by the practising professional and building management to ensure acceptable indoor air quality. The Study also recommended that the provisions of certain existing regulations should be strengthened to address the issue of indoor air pollution by making reference to the Code of Practice.
8. The Study recommended that indoor air quality at residential premises should be controlled on a voluntary basis and the Government should initiate public education to bring the issue of indoor air quality to the attention of the general public.
9. For office and public places, the Study has proposed 4 options for institutionalising the control of indoor air quality within the Administration :-
- Option A : Self-regulation;
- Option B : Making use of existing legislation and system;
- Option C : Enhancing existing legislation through amendments; and
- Option D : Developing a set of new legislation on indoor air pollution.
Other than Option D, the other options can be adopted in various combinations for implementation. The Study proposed that a more comprehensive mechanism to strengthen the control over indoor air pollution (i.e. Option D) may be warranted subject to the review of the situation by the Management Group in a period of 3 years.
10. The Study also recommended that institutions with susceptible groups including schools, hospitals and homes for the young, the aged and the sick should be further studied.
PROPOSED PRINCIPLES AND FRAMEWORK FOR THE CONTROL OF IAQ
11. Based on the findings and the recommendations of the Study, and the views of Government departments and professional bodies, a more comprehensive mechanism to strengthen the control of indoor air quality will be developed. The programme will be initiated in a progressive manner, starting with those buildings and premises where existing legislation can be used to deal with indoor air quality. This progressive control will represent a mix of Options A to C as recommended by the Study.
12. It is considered that the control of indoor air quality should be based upon the principle of self-regulation, either through administrative or statutory means. This means that building owners will need to employ suitably qualified personnel to check and certify that the indoor air quality of their buildings or premises complies with the standards set out. This will avoid the need to establish a large team of public officers to carry out inspections and surveillance. Use can also be made of the existing legislative framework or amendment of the appropriate legislation where necessary to enhance indoor air quality.
13. The Administration will review the position and consider the need to broaden the scope or introduce a set of dedicated legislation on the control of indoor air quality three years after implementation of the indoor air quality programme.
Indoor Air Quality Objectives
14. An important element for a proper indoor air quality programme is the adoption of a set of consistent indoor air quality standards by different departments and bureaux. These standards should be comparable to the international standards adopted by appropriate authorities. It is intended over the next year to develop a set of Indoor Air Quality Objectives for Hong Kong. A 3-Level approach is being considered:
- Level 1 represents very good indoor air quality that a high class and comfortable building should have. This level should be comparable to the best available indoor air quality standards.
- Level 2 represents the recommended indoor air quality standards that provide protection to the public at large including the very young, the aged and pregnant women.
- Level 3 represents the indoor air quality required to protect workers and employees.
It is expected that the 3-level Indoor Air Quality Objectives will encourage building owners and property management to pursue the best standards, as the merits of having greater prestige and higher market value for their building will serve as a major incentive to achieve a higher standard.
Code of Practices
15. In addition to the proposed 3-level Indoor Air Quality Objectives, it is also necessary to provide a comprehensive Code of Practice to define and specify the procedures, measures and methodologies that should be followed to evaluate indoor air quality as well as to achieve the Indoor Air Quality Objectives. This Code of Practice will act as a guide for the public and as the reference document for public and private sector professionals. The Study has already prepared a set of draft Code of Practice for this purpose. The draft Code of Practice will be used as the basis for consultations early next year.
16. The Government has already set up an inter-department Indoor Air Quality Management Group, chaired by the Planning, Environment and Lands Bureau and comprising relevant departments and bureaux, to co-ordinate the development on the control of indoor air quality. Subject to comments by members, the Government will proceed to consult the public, building management, relevant trade organisations and professional bodies on strengthening the existing programme or statutory provisions and on the draft Code of Practice to address the issue of indoor air pollution. Our aim is to formulate a comprehensive indoor air quality management programme for improving indoor air quality within 1999. To bring the issue of indoor air quality to the attention of the general public, the Government will launch a public education and publicity campaign to increase public awareness and understanding of the importance of indoor air quality.
17. Members are invited to note the findings and recommendations of the Study and to comment on the proposed way forward for the overall control of indoor air quality in Hong Kong as outlined above.
Planning, Environment and Lands Bureau
In the Second Review of the 1989 White Paper on Pollution issued in November 1993, the Government recognised the existence of potential health risk and problems associated with indoor air pollution. As an initial step to address the issue, an 18-month Consultancy Study on Indoor Air Pollution in Offices and Public Places was commissioned in October 1995. The Study was carried out by EHS Consultants Limited and managed by a Steering Group chaired by the Environmental Protection Department. Other members in the Steering Group included the Planning, Environment and Lands Bureau, Architectural Services Department, Electrical and Mechanical Services Department, Labour Department and Department of Health.
2. The Study
The Study was to characterize and quantify the indoor air pollution in office premises and selected public places in Hong Kong, assess the causes of the pollution problems, and recommend the most suitable control strategy. It comprised (a) questionnaire survey, (b) field sampling and laboratory analysis, (c) statistical analysis of the results, (d) study on the practice of other countries. The Study also identified the measures to mitigate indoor air pollution and prepared a draft Code of Practice on the management of IAQ, made proposal on the IAQ objectives, produced a mathematical model to predict the levels and exposures of common indoor air pollutants. It also proposed the approach and action on control of IAQ in residential premises.
2.1 Questionnaire Survey
The questionnaire survey was to gauge the indoor air quality (IAQ) situation of offices and public places in Hong Kong and the associated medical symptoms, and to facilitate subsequent correlation analysis with the characteristics of the occupants/ premises and other surveyed parameters. The questionnaire design was based on the US National Institute for Occupational Safety and Health (NIOSH) with slight modifications to suit local conditions. It consisted of two parts: a telephone survey on 2,000 respondents and an on-site survey on 1,183 occupants of 40 selected office premises. The occupants' perception of the IAQ in their workplace was gauged by expressions of satisfaction, and by calculating a Building Symptom Index (BSI) based on responses to questions about medical symptoms which would go away after leaving the workplace. Building occupants' perception is traditionally considered an important indication of sick building syndrome, given the health symptoms associated with it.
2.2 Detailed Measurements
The sampling protocol for field measurement was based on the US Environmental Protection Agency's BASE (Building Assessment Survey and Evaluation) study and modified as necessary to cope with the local constraints. Detailed monitoring and laboratory analysis of 40 offices was conducted between March and October 1996. To assess the extent to which air quality problems are due to seasonal variations, a longitudinal study covering summer and winter months for five out of the 40 office premises was made. A pilot study of IAQ in public places, which looked at selected samples of twenty restaurants, eight shopping malls, five cinemas, two wet markets and selected concourses/platforms of the Mass Transit Railway, was also conducted.
2.3 Statistical Analysis
Extensive statistical analysis was made to establish the degree of correlation between occupants' reported perceptions about IAQ and the tangible, measurable parameters. The consultants also looked into the correlation between perceptions and specific medical symptoms.
2.4 Other Countries' Practice
The Study also surveyed the relevant legislation, regulations and current practices on the control of IAQ in eight developed countries, namely Japan, United Kingdom, USA, Australia, South Korea, Singapore, Canada and Sweden. The study of the experiences in these countries provided the background information which is particularly useful in formulating the strategy to institutionalise IAQ for Hong Kong.
3. Major Findings
3.1 Questionnaire Survey
The questionnaire survey found that some 32% of the respondents were dissatisfied with the IAQ of their workplace. This figure is comparable to that reported in similar studies by the World Health Organisation (WHO).
3.2 Detailed Field Measurements
In the field measurement survey, carbon dioxide was the pollutant most often violated the international standards on IAQ: in the summer survey, 37.5% of offices had, over an 8-hour period, a mean carbon dioxide level exceeding 1,000 ppm 1. These excessively high levels of carbon dioxide were found to be caused by the high occupancy density in Hong Kong and inadequate ventilation. Indeed the fresh air content provided by the air-conditioning systems in 90% of the office buildings was found to be insufficient and well below the minimum requirement of 7.5 litres per second per occupant specified by the revised ASHRAE Standard 62-1989R of the American Standard for Heating, Refrigeration and Air-conditioning Engineering.
As a result of inadequate ventilation, the bacteria count in terms of "colony forming units per cubic meter" (cfu/m3) was higher than the recommended level of 1,000 cfu/m3 in 20% of the offices included in the summer survey. Fungal levels exceeded the recommended level (500 cfu/m3) less often but toxigenic species such as Aspergillus versicolour and Penicillium aurantiogriseum were found in over 10% of the premises. The dust collected in these premises all contained quantities of glucan and endotoxin (which cause inflammation and come from fungi and bacteria respectively) as well as dust mite allergens. These are thought to contribute to the allergic reactions experienced by many people in indoor environments.
Formaldehyde levels were also found to be above the WHO guideline of 100 mg/m3 in 32.5% of the offices in the summer survey. Formaldehyde emissions were associated mainly with chipboard, plywood using urea formaldehyde as an adhesive, and some coating polymers used to treat the surface of upholstery. Apart from formaldehyde, other volatile organic compounds were found in levels below the WHO guidelines or less than 5% of the threshold limit values (time-weighted average) used in industrial workplaces.
There were four premises where the levels of organic compounds, such as toluene, xylene (o-, m- and p-) and benzene, were exceptionally high. This was found to be due to the use of thinner in painting and woodwork during the redecoration of offices on the same floor as the offices where the sampling was taking place. This shows the importance of monitoring and controlling activities which may affect other occupants sharing the same floor and/or the same ventilation system.
3.3 Statistical Analysis
In the statistical analysis, the results showed significant correlation between the occupants' perceptions and measured parameters of IAQ including temperature, humidity, air change per hour, and levels of carbon dioxide, carbon tetrachloride, dichlorobenzene, bacteria and fungal counts. There was also a positive correlation between occupants' perceptions and 21 medical symptoms. For other parameters such as formaldehyde, toluene, xylene (o-, m- and p-) and trichloroethylene, the correlation, although significant, showed a reverse trend. These findings suggest that, while occupants are aware of environmental conditions such as the level of carbon dioxide and temperature, their sensitivity to important pollutants such as formaldehyde and organic solvents associated with thinners (decoration work), may be overshadowed by the "feel good" factor associated with newly decorated premises. This shows the importance of conducting both questionnaire surveys of occupants and sophisticated analytical tests of volatile organic compounds and formaldehyde: the former, to obtain a good indication of the general indoor environment, and the latter to ensure a thorough investigation of IAQ.
There was no significant correlation between levels of pollutant in indoor air with outdoor air except for respirable suspended particulates, with indoor air at a lower level as dust was trapped by filters in the ventilation system. Pollutants which showed higher levels indoor from outdoor had indoor emission sources, such as carbon dioxide, carbon monoxide, formaldehyde, volatile organic compounds, radon as well as bacteria and fungal counts. This demonstrates the importance of controlling the indoor air quality which can effectively reduce exposure of occupants in an indoor environment.
By carrying out a detailed survey of 40 carefully selected representative office sites and the 2,000 questionnaire surveys covering at least 800 identifiable buildings, it was possible to make a projection of the likely indoor air quality of the entire office building stock in Hong Kong within reasonable statistical confidence. The evidence of levels of indoor air pollution above international standards in many of the offices studied demonstrates the need for public guidance on how to manage the indoor air quality in these premises and recommended standards. A summary of the levels of indoor air pollutants found in the office buildings studied is provided in Table 1.
3.4 IAQ in Public Places
The pilot study of IAQ in public places found specific problems such as failure to comply with existing regulations or presence of pollutants at levels which violated internationally accepted guidelines. Table 2 provides a summary of the findings for public places.
For restaurants in general, the current smoking control measure is insufficient and efforts should be made to require segregation of ventilation systems to effectively control the entrainment of tobacco smoke to no-smoking areas. Adhering to a set of code of practice designed for this purpose or administrative requirements on smoking policy would yield positive improvement to the air quality indoor in such premises. For restaurants with naked fire in the dining area, the local exhaust provisions should be required to achieve IAQ objectives of nitrogen dioxide and carbon monoxide.
The results of the survey of the Mass Transit Railway (MTR) showed that IAQ at the MTR concourses and platforms during normal operational conditions was comparable even with the health/comfort-based IAQ objectives recommended in this Study for non-industrial and public places. The concentration of carbon dioxide inside train compartments during peak-hour period was high due to extremely crowded conditions, but it was still within the guideline for subway design in the USA.
3.5 Study on the Practice of Other Countries
The study showed that other countries are devoting resources to establishing standards, providing mitigation measures, and public education initiatives with the aim of improving indoor air quality. Of the advanced Asian countries, Japan has already introduced an indoor air quality control and monitoring requirement under the Ordinance of Office Sanitation, Singapore issued the Indoor Air Quality Guideline in 1996, and South Korea has an Indoor Air Quality Management Ordinance in the pipeline. In the west, the USA took the lead in proposing an Indoor Air Quality Bill under the Occupational Safety and Health Administration (OSHA) in 1993 but has so far failed to secure political agreement to the Bill. In the UK the issue also suffers from lack of support from political leaders. The Nordic countries, however, have been more active with Sweden and Finland adopting stringent codes to control IAQ under their respective ventilation laws.
In all these countries, there are already many regulations which in some way affect indoor air quality. That is also the situation in Hong Kong. Table 3 gives a list of existing responsibilities of government departments that are relevant to IAQ.
4. Recommended Measures for Improving IAQ
4.1 Code of Practice
The Consultants have prepared a draft Code of Practice (CoP) to help the practising professionals to ensure acceptable IAQ with reference to the established practice of other countries, including Canada, USA, Finland, Sweden, Australia and Singapore. It is recommended the final CoP should be finalized after consultation with the building developers, property managers and building professionals. It will serve as the cornerstone of the indoor air pollution control programme and should include the following essential elements:
- A clear definition of the responsibilities of the different groups of people who potentially have a direct or indirect impact on IAQ,
- A comprehensive list of technical measures to be implemented, and
- The indoor air quality guideline or objectives to be achieved and maintained.
4.2 IAQ Guidelines/Objectives
The Study recommended the use of the Finnish model of setting three levels of IAQ objectives complemented by the classification of office types according to their abilities to attain these objectives should be considered. In the system, the lowest level is to meet the basic health-based standard; and the two higher levels allow the owners to aim at optimal health outcomes when more resources and technical capabilities are available. The result of having greater prestige and higher values of the premises serves as the major incentives for the owners to pursue for better IAQ. The Study showed that the lowest level should have already been achieved in almost 65% of the office premises of Hong Kong.
4.3 Control Strategies
The Hong Kong Government's initiative to improve IAQ in Hong Kong premises will be taken forward by a special Management Group to be chaired by the Environmental Protection Department who was the convenor of the IAQ study. The main function will be to co-ordinate the implementation of a system of control based on the various options proposed; to review progress using indicators such as complaint cases; and to recommend action to make the scheme work more efficiently wherever necessary.
The Study made a very detailed evaluation of suitable systems for institutionalising the control of IAQ in Hong Kong. Four options were identified, viz.
- Option A: Self regulatory
- Option B: Making use of existing legislations
- Option C: Amendment to existing legislations
- Option D: Statutory control under new legislation
For Option A, the CoP will be issued as guidelines for the professionals and building management on a self-regulatory basis. This option has the advantages of a fast-track programme, flexible in actual implementation and with little resistance anticipated from the affected parties. The effectiveness of implementation, however, cannot be guaranteed.
Option B makes use of the provisions of certain existing regulations by administrative means such as through the drafting of Technical Memorandum, to make reference to the CoP. Amendment to those regulations is not required. Option C is to amend the existing regulations or licensing provisions of Chapters 123, 132 and 172 for the enforcement of the CoP. Both Options B and C provide the Government with the enforcement power but require certain lead time and much effort in coordinating the various control bodies. Option D involves the introduction of a new and comprehensive legislation to provide the most effective coverage for IAQ enforcement. However, the legislative process will be lengthy and that considerable resource implications and restructuring should be anticipated.
Other than Option D, the other options can be adopted in various combinations for implementation. The Management Group should determine the best option and oversee all the related activities and progress and review the situation in three years' time.
4.4 Residential Premises
The indoor air quality of residential buildings is also an important area, but, from a practical point of view, can only be controlled on a voluntary basis. The government should initiate public education to promote the importance of maintaining good practice related to indoor air quality. Public awareness campaigns are essential to bring the issue of IAQ to the attention of the general public. It would be useful to establish a contact/information centre to which questions and requirements for measurements could be addressed.
5. Recommended Further Studies
In light of the findings from this Study, the consultants recommended a more detailed study on the economic evaluation of the impacts of IAQ which may take the form of a government initiated cost-benefit analysis of improvement in IAQ. There are obviously costs in upgrading 'hardware' set up (such as ventilation) and 'software' management system in enforcement, monitoring, licensing and complaints investigation related to IAQ. However, the consultants in its preliminary economic analysis has illustrated that such cost will be more than offset by the gain made in the reduction of medical cost and regaining the loss in productivity due to 'sickness' at work.
The consultants also recommended further research into indoor air quality problems in educational institutions which carry out a variety of activities from laboratory work to physical exercise, and medical institutions where special control of gases, chemicals and micro-organisms is necessary. Institutions with susceptible groups including schools, hospitals and homes where the young, the aged and the sick are present, should also be considered as cases for further study.
6. Conclusion and Way Forward
The Study concluded that indoor air pollution in Hong Kong is very similar to that of other developed countries. The air quality in about one-third of the office buildings was perceived as unsatisfactory by the occupants and has violated WHO or relevant overseas standards.
The approach adopted so far in controlling IAQ in Hong Kong is through establishing basic air quality standards and ventilation requirements. There are already statutory provisions to require buildings, workplaces and specified public places such as restaurants and cinemas to comply with basic ventilation and air quality standards but these responsibilities are split among a number of government departments. A more comprehensive mechanism to strengthen the control over IAQ may be warranted subject to a review of the situation by the Management Group in three years' time. For the interim, a comprehensive CoP giving a set of IAQ objectives and good practices on the management and enhancement of IAQ has been developed for use by the related professionals and building management. The Study recommended that the provisions of certain existing regulations should be further utilised to address the issue of indoor air pollution by making reference to the CoP.
Improving IAQ has been shown to bring economic benefits through higher worker productivity and lower medical costs. The assurance from the Government to actively maintain acceptable IAQ standards in Hong Kong buildings is an important element for international community to decide to work and live in Hong Kong. IAQ also plays a part in Hong Kong's competitiveness as an international business centre in the region. With a concerted effort and a sound institutionalised scheme of control, the IAQ of our buildings can be made more acceptable and provide a healthy environment for people to live and work in. Government buildings should take the lead for voluntary control and that should be good news for business, public and government alike.
1. "1000 ppm" is the standard recommended by the American Standard for Heating, Refrigeration and Air-conditioning Engineering (ASHRAE) - the body responsible for setting internationally recognised standards in indoor air quality
Table 3: Summary of Responsibilities of Government Departments Relevant to IAQ
Relevance to IAQ
Building Ordinance Cap. 123
Requirement for mechanically ventilated premises to provide 5 air changes per hour.
Provisional Urban /Provisional Regional Council (PUC/PRC)
Public Health & Municipal Services Ordinance, Cap. 132
Dampers, filters & precipitators are inspected yearly by registered ventilation contractor.
Specified ventilation rates for scheduled premises.
Places of Public Entertainment Regulations, Cap.172
Requires provision of sufficient ventilation to the public places.
A fresh air supply requirement of 13m3/h/person is imposed on all entertainment machine centres.
Factories & Industrial Undertakings Ordinance, Cap.59
Requirements to protect workers (workplace safety and measures of work practice as well as medical surveillance).
Occupational Safety & Health Ordinance,
Requires the provision of safe and healthy workplace for office workers in addition to industrial workers. Provision of adequate ventilation & air within workplace should be kept free of impurities.
Health Department, Commission of Police, PUC/PRC, TV & Licensing Authority
Smoking (Public Health) (Amendment) Ordinance, Cap. 371; Code of Practice under Broadcasting Authority Ordinance
Control measures relating to prohibition of advertisements, designated "No Smoking" areas, "No Smoking" signs, etc.
Customs & Excise Department
Consumer Goods Safety Ordinance, Cap. 456
Ozone Layer Protection Ordinance, Cap. 403
Air Pollution Control Ordinance, Cap. 311
Control of import of consumer goods with focus on product safety and enforcement of import control on ozone-depleting substances & asbestos through import licensing (as authorised by EPD).
Agriculture & Fisheries Department
Pesticides Ordinance, Cap. 133
Control of import, manufacture, supply & sale of pesticides (but no control of use of registered pesticides).
Environmental Protection Department
Air Pollution Control (Amendment) Ordinance, Cap. 311
Established Air Control Zones and the associated Air Quality Objectives
Control of asbestos in environment.