A Need for School Indoor Air Quality Management in Hong Kong

Indoor air quality (IAQ) in the workplace and residential environments has caught the attention of scientists, entrepreneurs, and the public in recent years. Many studies have found indoor pollutant levels greater than outdoor levels. Good IAQ is very important to our health because people usually spend 70% of their time indoors. Air pollutants generated by outdoor sources affect the environment as well as health. Poor IAQ can lead to discomfort, ill health (e.g., headache, itchy eyes, respiratory difficulties, skin irritation, nausea, and fatigue), absenteeism, and reduced productivity in the workplace. Children, elderly, and people with existing respiratory or heart problems are susceptible to the effects of poor IAQ. By contrast, good IAQ safeguards the health of the building occupants and contributes to their comfort and wellbeing. Good air quality is important for everyone, and especially more important for certain vulnerable members of the household, including babies, children, pregnant women and their unborn babies, the elderly, and those who suffer from respiratory or allergic diseases, such as asthma.


Most people in Hong Kong spend the majority of their time at home, in the office, and other indoor environments. Research has found that many indoor air pollutants may cause adverse health effects and illnesses. In 1998, IAQ Management Group was established by the Environmental Protection Department (EPD) to coordinate actions on the control of IAQ to implement the IAQ Management Programme. In September 2003, the EPD (i) issued the Guidance Notes for the Management of Indoor Air Quality in Offices and Public Places, (ii) launched the voluntary IAQ Certification Scheme for enclosed offices and public places served by mechanical ventilation and air conditioning (MVAC) systems, and (iii) established the IAQ Objectives for Office Buildings and Public Places (IAQ Objectives). The new IAQ Objectives, comprising 13 parameters (including a new parameter of mould added in 2019), are used to evaluate and to assess IAQ in offices and public places served by MVAC systems for human comfort. The assessment has two classes of achievement, namely, Excellent Class and Good Class. In 2011, the Audit Commission (Audit) reviewed the initiatives for the government to improve IAQ with a focus on the implementation of the IAQ Management Programme. Audit noted that Guidance Notes only included office buildings and some public places, but not schools, whereas some countries, such as the U.S., extend their IAQ programmes to cover schools. Hence, Audit recommended to consider publishing IAQ guidance notes for childcare centres, kindergartens, and schools.


The IAQ of kindergarten and primary school premises in Hong Kong is unknown as research on this subject is limited. Studies around the world have revealed that IAQ has a more significant effect on children than on adults because children breathe greater volumes of air compared to adults (1). In addition, the effects of IAQ on the health of children may be delayed until they are much older, such that identifying poor IAQ as the source of the problem is more difficult (2). Attention is necessary towards IAQ levels inside schools, especially kindergartens, as the Canadian Lung Association CLA (2002) reports that 25% of school absenteeism is caused by asthma. In addition, school absenteeism and medication for asthmatic children increased proportionately with the deterioration of their respiratory systems, which was caused by the high amount of particulate matter inside the schools (3).


Another study found that schools have four times the number of occupants per square foot as offices. Therefore, when children breathing high amounts of polluted air, it will produce more polluted air than fresh air intake. VOC concentrations were relatively high at high temperature, and the concentration of respirable dust was found to be high in classrooms with low ventilation rates and high humidity.  A 20% reduction in absenteeism was observed when the indoor relative humidity increased from 22% to 35%. The reduction in absenteeism was due to the reduction in the survival rate of airborne microorganisms at elevated relative humidity. In addition, poor outdoor air quality has prompted schools to convert naturally ventilated classrooms into air-conditioned classrooms. A Swedish study involving the examination of total volatile organic compounds (TVOC) and CO2 in 185 schools (4) revealed that outdoor contamination sources significantly affected IAQ, and cleaning products and floor polish temporarily added to the pollution content in classrooms. Other important factors that influenced IAQ is the extent of human activities (number of students, length of lessons, breaks) on the premises.


Poor IAQ in schools can negatively affect the health, productivity, and attendance of children. Failure to prevent indoor air pollution in the classrooms can increase the risk of long- and short-term health problems for both students and staff, reduce the productivity of teachers, and degrade the student learning environment and comfort. Substandard environmental conditions in schools, such as insufficient cleaning or inadequate ventilation, can cause serious health problems for children. Maintenance issues in schools, such as mould and moisture, or excessive use of cleaning chemicals, have been shown to trigger asthma and allergies. According to the Centers for Disease Control and Prevention (CDC), asthma is one of the leading causes of school absenteeism (5). Multiple studies have also indicated that the overall performance of children decreases with illnesses or absences from school (6, 7).


Reports indicated that schools could initiate measures to improve IAQ to advance the health and performance of students and school staff. For example, health, attendance, and academic performance can improve with increased maintenance (8-9). Schools with better physical conditions also showed improved academic performance of children, whereas schools with few janitorial staff and high maintenance backlogs showed poor academic performance. Since the ventilation rates in most schools are below the recommended levels, ensuring adequate air ventilation rates in all classrooms can reduce student absenteeism and the transmission of infectious diseases, improve the overall health and productivity of teachers, and improve test scores and student performance in mental tasks (10–13).


In the U.S, studies revealed that half of their 115,000 schools have problems associated with IAQ. Students are at greater risk because of the long hours they spend in school facilities and their susceptibility to pollutants. If students and teachers are not healthy and comfortable, then the learning and teaching effectiveness may suffer, which consequently affects the academic achievement of students and the overall performance of teachers. Therefore, IAQ has become an increasingly important issue in American schools, which have implemented IAQ programme(s) since 2000s. The Environmental Protection Agency (EPA) developed the Indoor Air Quality Tools for Schools Program to help schools prevent, identify, and resolve their IAQ problems. Nowadays, many effective school IAQ management programmes have been implemented includes moisture management, integrated pest management, and adequate ventilation, and controls of environmental triggers that are linked with asthma and other health initiatives.


In reality, indoor air can be 10 times as polluted as outdoor air. Failure to identify and establish indoor air pollution status can increase the risk of long- and short-term health problems. Therefore, guidelines should be provided to schools in Hong Kong for the implementation of IAQ improvement measures. In the long term, how to improve existing Hong Kong IAQ policies and standards in school or other learning environments should be implemented.


1.     Torres, V. M. (2000) Indoor air quality in schools. Austin, TX: University of Texas, Texas Institute for the Indoor Environment.

2.     USEPA (1996) Indoor Air Quality Basics for Schools. United States Environment Protection Agency, U.S.

3.     Peters A, Dockery DW, Heinrich J, Wichmann HE., (1997) Short-term effects of particulate air pollution on

respiratory morbidity in asthmatic children. European Respiratory Journal. Vol. 10:4, pp. 872–879.

4.     J. Gusten, O. Strindehag Experiences of measures taken to improve the air quality in schools Air Infiltration Review, 16 (1995), pp. 5–8

5.     Centers for Disease Control and Prevention. National Center for Chronic Disease Prevention and Health Promotion. Healthy Youth! Retrieved July 14, 2009, from CDC’s Asthma Health Topics Web site: http://www.cdc.gov/HealthyYouth/ Asthma/ Also see Akinbami, L.J. 2006. The State of Childhood Asthma. United States, 1980-2005. Advance Data from Vital and Health Statistics: no 381, Revised December 29, 2006. Hyattsville, MD: National Center for Health Statistics.

6.     Silverstein, M.D., J.E. Mair, et al. 2001. "School attendance and school performance: A population-based study of children with asthma.” Journal of Pediatrics 139(2):278-283.

7.     Moonie, S., D.A. Sterling, et al. 2008. "The relationship between school absence, academic performance, and asthma status.” Journal of School Health 78:140-148.

8.     For a summary of the impact of indoor environmental quality on work and school performance, as well as other IAQ research findings, see the IAQ Scientific Findings Resource Bank (SFRB) established as a cooperative venture between EPA and the Lawrence Berkeley National Laboratory: Accessible at http://www. iaqscience.lbl.gov/performance-summary.html.

9.     Schneider, M. 2002. "Public school facilities and teaching: Washington, DC and Chicago.” 21st Century School Fund, Washington, D.C.

10.  Branham, D. 2004. "The wise man builds his house upon the rock: The effects of inadequate school building infrastructure on student attendance.” Social Science Quarterly (85)5.

11.  Apte, M., W. Fisk, and J. Daisey. 2000. "Associations between indoor CO2 concentrations and sick building syndrome symptoms in U.S. Office buildings: An analysis of the 1994-1996 BASE study data.” Indoor Air 10(4):246-257.

12.  Shendell, D. G., R. Prill, et al. 2004. "Associations between classroom CO2 concentrations and student attendance in Washington and Idaho.” Indoor Air 14(5): 331-41.

13.  Sundell, J., H. Levin, et al. 2011. "Ventilation rates and health: multidisciplinary review of the scientific literature.” Indoor Air 21: 191-204. http://onlinelibrary. wiley.com/doi/10.1111/j.1600-0668.2010.00703.x/pdf

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