Joint Submission in Response to the Government’s Consultation on the Regulatory Regime on Basic Housing Units

Clean Air Network (‘CAN’) is the only non-governmental organisation in Hong Kong focussed on air issues. CAN seeks to achieve its vision ‘Clean Air for All’ in Hong Kong through constructive dialogue and integrating various resources.

Health In Action (‘HIA’) was established in 2011 and is a registered non-governmental organisation in Hong Kong. HIA firmly believes that everyone has the right to health regardless of occupation, economic status, gender, ethnicity, living environment or education level. With this belief, HIA is committed to the development of primary care by adopting social-medical integration through collaboration and practices; promoting health as the core of different sectors, and improving the health-related social determining factors. The organisation explores and understands how social determining factors affect the health of different communities.

Summary

We welcome initiatives of the Government to improve the living conditions and health of the residents of subdivided units. There is a lack of city-wide data about the indoor air quality at subdivided units; however, research done by civil society has indicated issues with fine suspended particulates (‘PM2.5’) pollution, excessive carbon dioxide concentration and poor ventilation at subdivided units. This can harm the health of the residents of subdivided units, especially children, increasing the risk of respiratory diseases, cancer and other conditions, and contribute to healthcare costs.

To protect the health of the residents of subdivided units and achieve health equity regardless of income levels, we make the following recommendations:

• Strengthening the enforcement of existing regulations relating to ventilation in buildings;
• Collecting information on compliance of existing regulations among subdivided units;
• Collecting data on indoor air quality at subdivided units; and
• Providing accessible, affordable and available primary healthcare services.

Severity of Indoor Air Pollution at Subdivided Units

There is no comprehensive data about indoor air quality at subdivided units in Hong Kong; however, civil society has conducted studies at about 30 units.

CAN monitored carbon dioxide, PM2.5 and total volatile organic compound levels at two subdivided units in Sham Shui Po continuously for about one month and a half from September to October 2024. The results were as follows:

For comparison, the ‘good’ level of carbon dioxide under the voluntary Indoor Air Quality Certification Scheme for Offices and Public Places of the Environmental Protection Department (‘EPD’s scheme’) is 1,000ppm, averaged over eight hours. The ‘excellent’ level is 800ppm.

Figures 1 to 4 show the carbon dioxide and PM2.5 concentrations at the two subdivided units each day. The concentration levels frequently exceeded the objectives set by the Government.

Hong Kong Red Cross monitored indoor air quality at nine subdivided units in 2023, and found that the carbon dioxide levels in more than half of them were unsatisfactory [3].

Lingnan University measured PM2.5 levels at 20 subdivided units in Sham Shui Po in 2023, and found the average concentration to be 60.1µg/m3, more than four times the daily average level recommended by the World Health Organization (15µg/m3) [4].

In July 2024, members of the Legislative Council and Commission on Poverty visited a subdivided unit in Kwai Chung upon the invitation of the Anti Poverty Alliance. CAN joined the visit to give our perspective on indoor air quality. The toilet shared by the resident of that subdivided unit and those of nearby units had very severe mould problems (figure 6). The visit and the poor living conditions at the subdivided unit have been covered by the media [5].

Health Impact of the Pollution

Indoor air quality plays an important role in infection control. Carbon dioxide is an indicator of ventilation. Maintaining carbon dioxide levels below 800ppm has been found to keep the reproduction number below one (i.e. each infected person would infect less than one person and hence the outbreak would be slowed down) for highly transmissible pathogens in a classroom setting [6]. In contrast, as mentioned above, the carbon dioxide levels at the two subdivided units monitored by CAN exceeded 2,000ppm continuously repeatedly.

Prolonged exposure to excessive carbon dioxide can also lead to drowsiness, headaches, nausea and reduced cognitive performance [7].

PM2.5 has been classified as a group one carcinogen [8], and found to increase the risk of many other conditions, including poor lung function [9], reduced birth weight, early birth [10], diabetes [11].

Mould is listed as one of the indoor air quality parameters by the Government. Chronic exposure can induce allergies and asthma [12].

The School of Public Health of The University of Hong Kong estimates that PM2.5 and other air pollutants led to 3,500 premature deaths and economic loss of $41 billion in Hong Kong in 2024 [13]. Indoor air pollution at subdivided units is particularly harmful to children, as the foetal to adolescent stage is a critical window for growth, and the immune and respiratory systems are still maturing [14]. Air pollution can have a lasting impact on the health of children even after they have grown up. It may also affect the mental health [15] and cognitive ability of children [16]. Living in very poor conditions, such as the subdivided unit mentioned above with severe mould problems, can also harm the dignity of children. The health of children is protected by the International Covenant on Economic, Social and Cultural Rights (article 12) and the Convention on the Rights of the Child (article 24), both of which apply to Hong Kong. The survey commissioned by the Task Force estimated 16% of the residents of subdivided units are aged below 15 [17].

Recommendations for the Government

It is important for the Government to gain a more comprehensive understanding of the indoor air quality at subdivided units in Hong Kong, and formulate measures to improve it based on the findings. Specifically, we make the following recommendations:

1. Strengthening the Enforcement of Existing Regulations Relating to Ventilation in Buildings
(a) Under existing regulations for buildings in Hong Kong generally, not just for subdivided units, there shall be windows of an aggregate area not less than one-tenth of the floor area in every room used for habitation, and such windows shall face directly into the external air (regulation 30(2)(a), Building (Planning) Regulations, Cap. 123F). We observe that the standard for windows proposed for ‘basic housing units’ by the Housing Bureau in the consultation document is lower than the above-mentioned standard stipulated by the Building (Planning) Regulations. The minimum standard proposed for basic housing units can be met by having only one openable window facing a street, service lane, yard, re-entrant, etc, coupled with a mechanical ventilation system. There is no requirement relating to the size of such a window.

(b) Adequate ventilation, as made possible by the sizes of windows, is important for maintaining air quality and infection control. Such standards for ventilation in existing regulation should apply to subdivided units equally, from a legal standpoint and for health equity for all regardless of income levels.

(c) Currently, if a building does not meet such standards stipulated by regulation 30(2)(a)(i) Building (Planning) Regulations, the Buildings Department may require the alteration of the building (section 24(1), Buildings Ordinance, Cap. 123). We recommend that the Government, with appropriate arrangements to support tenants affected, strengthen the enforcement of the Buildings Ordinance, particularly in relation to ventilation, at subdivided units and other forms of inadequate housing.

2. Collecting Information on Compliance of Existing Regulations among Subdivided Units
While the survey of subdivided units commissioned by the Task Force covered the demographics of the residents of subdivided units and the conditions of the units, such as the proportion having openable windows, the survey did not cover the proportion of units meeting the requirement in the Building (Planning) Regulations of having windows of an area not less than one-tenth of the floor area. We recommend that the Government conduct a survey on this among subdivided units in Hong Kong to understand the situation better.

3. Collecting Data on Indoor Air Quality at Subdivided Units
In the Clean Air Plan 2035, the Government states that it would monitor indoor air quality at selected sites with micro-sensors. Given the lack of city-wide data about the indoor air quality at subdivided units and other forms of inadequate housing, we recommend that the Government conduct a study on the indoor air quality at various inadequate housing spaces in Hong Kong. Based on the findings, the Government should start formulating more rigorous measures to improve indoor air quality at subdivided units and other inadequate housing spaces.

4. Providing Accessible, Affordable and Available Primary Healthcare Services
As discussed above, the living conditions of subdivided units can jeopardise the health of the residents and lead to respiratory problems and other issues. However, the accessibility, availability and affordability of current primary healthcare services that are addressing these respiratory health issues is below expectation. Community Living Rooms subsidised by the Government do not handle health issues, while the District Health Centres do not target respiratory issues. It is not desirable for patients to resort to the accident and emergency services at hospitals while the conditions of a significant number of those affected are subtle but need long-term care. The Hospital Authority has recently proposed raising the fees for emergency services, which would increase the financial burden of low-income residents in subdivided units. We recommend that the Government expand the service covering a wide range of respiratory issues of subdivided units residents.

January 2025

Reference
[1] ‘Public consultation on Air Quality Objectives review launched,’ Hong Kong Government, 31 August 2023, https://www.info.gov.hk/gia/general/202308/31/P2023083100287.htm. This air quality objective is for ambient PM2.5, and we apply this to indoor PM2.5 in the absence of a specific objective for indoor PM2.5 in Hong Kong. As pointed out by the WHO, there is no convincing evidence of a difference in the hazardous nature of particulate matter from indoor sources as compared with those from outdoors. Therefore, its air quality guidelines for particulate matter outdoors are also applicable to indoor spaces. WHO, Guidelines for Indoor Air Quality: Selected Pollutants, 2010, https://www.who.int/publications/i/item/9789289002134.
[2] This is the threshold suggested by around 40 academics in a joint statement. Lidia Morawska et al., ‘Mandating indoor air quality for public buildings,’ Science 383, no. 6690 (2024): 1418-1420, https://www.science.org/doi/10.1126/science.adl0677.
[3] Hong Kong Red Cross, ‘Hong Kong Red Cross Column: Extreme Weather Troubles the Occupants of Inadequate Housing. Hong Kong Red Cross Launches a Project to Help Improve Living Environments,’ Ming Pao Weekly, 27 December 2023, https://www.mpweekly.com/culture/%e5%81%a5%e5%ba%b7/%e9%a6%99%e6%b8%af%e7%b4%85%e5%8d%81%e5%ad%97%e6%9c%83-%e6%a5%b5%e7%ab%af%e5%a4%a9%e6%b0%a3-%e4%b8%8d%e9%81%a9%e5%88%87%e6%88%bf%e5%b1%8b-232892 (Chinese only).
[4] Lingnan University, ‘Air Purifier Installation and Air Pollution Monitoring of Subdivided Units in Sham Shui Po Region,’ accessed 31 December 2024, https://ln.maps.arcgis.com/apps/dashboards/ae2bcd1a63a248789fd6bd1259085ce7.
[5] ‘Landlords of Subdivided Units Overcharge Tenants for Water and Electricity. Low-Income Persons Suffer from Heat and Have to Save on Air-Conditioning Costs. Groups Call for Subsidies on Electricity Costs.’ On.cc, 28 July 2024, https://hk.on.cc/hk/bkn/cnt/news/20240728/bkn-20240728142929288-0728_00822_001.html (Chinese only).
[6] Note 2 above.
[7] ‘Carbon Dioxide’, Wisconsin Department of Health Services, accessed 4 January 2025, https://www.dhs.wisconsin.gov/chemical/carbondioxide.htm.
[8] International Agency for Research on Cancer, WHO, ‘Agents classified by the IARC Monographs, Volumes 1–137,’ accessed 4 January 2025, https://monographs.iarc.who.int/list-of-classifications.
[9] Cui Guo et al., ‘Long-Term Exposure to Ambient Fine Particulate Matter (PM2.5) and Lung Function in Children, Adolescents, and Young Adults: A Longitudinal Cohort Study,’ Environ Health Perspect 127, no. 12 (2019): 127008, https://pubmed.ncbi.nlm.nih.gov/31873044/.
[10] Rakesh Gosh et al., ‘Ambient and household PM2.5 pollution and adverse perinatal outcomes: A meta-regression and analysis of attributable global burden for 204 countries and territories,’ PLoS Med 18, no. 9 (2021): e1003718, https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1003718.
[11] Yuyuan Yi et. al, ‘Life Course Associations Between Ambient Fine Particulate Matter and the Prevalence of Prediabetes and Diabetes: A Longitudinal Cohort Study in Taiwan and Hong Kong,’ Diabetes Care, 48, no. 1 (2025): 93–100, https://diabetesjournals.org/care/article-abstract/48/1/93/157458/Life-Course-Associations-Between-Ambient-Fine?redirectedFrom=fulltext.
[12] Indoor Air Quality Management Group, Guidance Notes for the Management of Indoor Air Quality in Offices and Public Places, 2019, https://www.iaq.gov.hk/wp-content/uploads/2021/04/gn_officeandpublicplace_eng-2019.pdf
[13] ‘Hedley Environmental Index,’ School of Public Health, The University of Hong Kong, accessed 14 January 2025, https://hedleyindex.hku.hk/en/historical-data. There is no index measuring the cost of indoor air pollution or PM2.5 pollution only in Hong Kong.
[14] SL Lee et. al, ‘Review of Outdoor Air Pollution and Child Health in Hong Kong’, HK J Paediatr (new series) 18, no. 2 (2013): 69-76, https://www.hkjpaed.org/pdf/2013;18;69-76.pdf.
[15] See, for example, Emily Midouhas, Theodora Kokosi and Eirini Flouri, ‘The quality of air outside and inside the home: associations with emotional and behavioural problem scores in early childhood,’ BMC Public Health 19, no. 406 (2019), https://doi.org/10.1186/s12889-019-6733-1.
[16] See, for example, Emily Midouhas, Theodora Kokosi and Eirini Flouri, ‘Outdoor and indoor air quality and cognitive ability in young children,’ Environ Res 161 (2018):321-328, https://pubmed.ncbi.nlm.nih.gov/29182908/.
[17] Housing Bureau, ‘Regulatory Regime on Basic Housing Units: Consultation Document’, 2024, https://www.hb.gov.hk/eng/policy/housing/policy/tenancy_control/pdf/BHU%20consultation%20document_eng.pdf.