Ventilation Facilities Management for Older People in Care and Attention Homes

Abstract

Population ageing is a global trend, which is particularly pronounced in Hong Kong. The number of older people in Hong Kong has increased steadily from 0.18 million in 1971 to over 1.82 million in 2025. It is projected that by 2034 and 2069, the proportion of older people over 60 years old will reach 29% and 35% respectively. This rapid ageing imposes a substantial elderly care burden on Hong Kong, a densely populated city. Concurrently, age-related changes in older individuals profoundly affected all aspects of their lives, including physical health, psychological health, and independence. In light of these challenges, care and attention (C&A) homes have become an indispensable component of the elderly care industry in Hong Kong, aiming to ensure quality of life (QoL) for their residents in late life. However, poor indoor air environment (IAE) in C&A homes, characterized by multiple air pollutants (e.g., particulate matter (PM), formaldehyde, volatile organic compounds (VOCs), and carbon dioxide (CO2)) and thermal conditions (e.g., temperature and humidity), directly influences the QoL of older people. Respiratory diseases (e.g., asthma, chronic obstructive pulmonary disease, and lung cancer), cardiovascular diseases (e.g., heart diseases and stroke), and various health issues (e.g., mental disorders, cancer, and diabetes) are closely related to poor IAE, which are prevalent among older people, causing considerable mortality every year. These facts underscore the critical requirements for improving ventilation facilities management (VFM) and IAE in C&A homes. Nevertheless, specific guidance on VFM and IAE for the vulnerable older group in C&A homes remains lacking. Therefore, this study aims to investigate the relationships among VFM, IAE, and QoL and subsequently formulate targeted recommendations for VFM and IAE to enhance the QoL of older people residing in C&A homes.

A step-by-step research framework was designed and implemented to achieve the research objectives. Initiated with an extensive literature review on VFM, IAE, and QoL, key components and corresponding factors were identified to form the basis for a conceptual model. Specifically, the VFM construct encompassed three components, including space management (e.g., room space, layout, and orientation), heating, ventilation, and air-conditioning (HVAC) services (e.g., fans, air conditioners, and air purifiers), and supporting facilities (e.g., window, finishes, and furnishing). The IAE section comprised three main components (i.e., classic pollutants: carbon dioxide, VOCs, carbon monoxide, etc.; air flow: air velocity, air change rate, and odour; indoor thermal comfort: temperature and humidity). The QoL of older people living in C&A homes was conceptualized with multiple dimensions, such as physical health (i.e., physical pain, fatigue, injury, and sleep), psychological health (i.e., cognition and emotion), independence (i.e., activities of daily living (ADLs) and mobility), social functioning (i.e., social relationship and social interaction), and environment (i.e., senses of health, safety, and home). It was hypothesized that the VFM in C&A homes exerts both a direct influence and an indirect influence mediated by the IAE on QoL of older residents.

The large-scale questionnaire survey was adopted to investigate the interactions among VFM, IAE, and QoL. Using a designed questionnaire (i.e., including four sections: personal information, satisfaction with VFM, satisfaction with IAE, and self-reported QoL), face-to-face interviews were conducted with older people across 20 C&A homes in different districts of Hong Kong. A total of 196 valid responses were collected from those aged 60 or above who have lived in the home for over three months, passed the cognitive test without severe cognitive impairments, and consented to participate. Multiple statistical analytical methods were employed to analyze the quantitative data. The exploratory factor analysis and reliability test were used to ensure the robustness and internal consistency of the identified factors. Pearson’s correlation analysis was then performed on the validated VFM, IAE, and QoL factors to explore their bivariate relationships. Following this, a stepwise multiple linear regression further investigated the most prominent predictive relationships. Finally, structural equation modeling was applied to cross-validate the integrated relationships based on correlation and regression results. Only models that satisfied the criteria of multiple model fit indices and were significant at the 0.05 level were retained in the final model, demonstrating the VFM-IAE-QoL interactions. In addition, qualitative feedback was also collected to provide supplementary evidence for deep insights into the nature of these interactions.

To propose effective recommendations on VFM and IAE in C&A homes, a longitudinal case study was conducted to examine the seasonal variations. Three C&A homes in Hong Kong were purposely selected to represent diverse operational and architectural categories, including a self-financed home in a separate building, a private home on the first floor of a multifunctional building, and a government-subvented home occupying the ground and first floors of a residential building. On-site measurements were employed to document the current ventilation facilities in each home. Ubibot AQS1 sensors were positioned in the bedrooms of the selected C&A homes for one week per season to continuously monitor IAE parameters throughout the year. Meanwhile, the daily routine and subjective perceptions of instant IAE were repeatedly obtained from older residents across different time periods in each season. The linear mixed model was adopted to examine the main effects of season and time period, as well as their interactive effects, on both objective IAE and subjective perceptions. The recorded IAE data were compared with existing governmental guidance, revealing the specific areas requiring improvement. Current TVOC in C&A homes, especially in warm and humid seasons, and the three PM pollutants (i.e., PM1, PM2.5, and PM10) in relatively dry climates required effective control, whereas CO2 and formaldehyde remained at excellent levels throughout the year. Slightly higher temperature and relative humidity were preferred by older residents, though the cool and dry air benefited the overall IAE perceptions. The subjective perceptions served as the basis for identifying comfortable season-time period combinations, which were then used to derive recommended IAE ranges for C&A homes.

At the basis of the questionnaire survey results, an integrated VFM-IAE-QoL model was established, confirming the complex interactions among the three constructs. Specifically, room space positively influenced the uniformity of room temperature, which further reduced sleep disorders among older people. Indoor layout positively impacted the ADLs, mobility, and social support of older residents in C&A homes. Furthermore, layout also contributed to the acceptability of air movement, odor intensity, and perceived air quality, which were found to benefit emotions and social relationships, physical pain, and sleep disorders and social support, respectively. Openings in C&A homes improved the acceptability of air movement and the sense of safety for residents. Air conditioner influenced QoL directly by enhancing the sense of home, and indirectly by affecting dust and dirt to impact personal pains, fatigue, and cognition, and by improving perceived air quality to reduce physical pain and sleep disorders and improve social support. Control over ventilation facilities supported the ADLs and mobility, whereas it could increase the injuries. Regarding supporting facilities, windows were beneficial for the social functioning of older people. Finishes were found to improve cognition and ADLs and reduce injuries. Indoor finishes also positively influenced dust levels in C&A homes, which in turn affected physical pain, fatigue, and cognition among older people. Furniture in C&A homes could directly promote emotions and social relationships, while an indirect pathway through acceptable air movement was also identified. Finally, indoor cleaning practices impacted the mobility and sense of health among older residents, as well as the dust and dirt and perceived air quality in C&A homes.

The final VFM-IAE-QoL model provided a foundation for specific recommendations to enhance QoL of older people in C&A homes, such as multi-zone temperature monitoring and control to ensure unform distribution, openings on partitions to facilitate cross-ventilation and social exposure, airflow plan to avoid contaminants spread, properly matched HVAC systems with room geometrics to ensure adequate ventilation and temperature adjustment, high wall-mounted or ceiling mounted air conditioners to minimize direct airflow to beds or seats, high-efficiency filtration within in HVAC units to reduce particulate accumulation, reachable ventilation control for older people with limited mobility, integrating ventilation adjustments and window operation into daily rehabilitation, avoidance of porous finish materials and anti-static coating to reduce dust, face-to-face or circular furniture configurations to support interaction and air movement, scheduled cleaning services with low-VOCs and fast-dry agents, resident feedback mechanisms for ventilation performance, accessibility, and cleaning, etc. Furthermore, the longitudinal IAE and corresponding perceptions facilitated the development of detailed comfort zones specifically for older people living in C&A homes. For instance, the suggested temperature range should be adjusted from the current 20.0 to 25.5 ℃ to a higher interval (e.g., 23.6 to 28.5℃). Relative humidity is generally suggested to be maintained between 55% and 79%. Strict control of indoor volatile organic compounds and fine particulate matter (e.g., PM_2.5 and PM₁) is required. This study employed a mixed-method approach, combining the questionnaire survey to develop the VFM-IAE-QoL model and the longitudinal case study to investigate VFM and IAE for typical C&A homes in depth. Several research limitations have been acknowledged, combined with future research directions to address these limitations. Overall, this study provided theoretical insights to elaborate the complex VFM-IAE-QoL interactions and practical recommendations to enhance the living environment for older people residing in C&A homes.

Date of Award	12 Aug 2026
Original language	English
Awarding Institution	City University of Hong Kong
Supervisor	Mei-yung LEUNG (Supervisor)