MPhil Thesis Presentation - Indoor Air Quality in Hong Kong Residential Environments: A Study of Volatile Organic Compounds and Greenhouse Gases

People spend the majority of their daily lives indoors. Extensive research indicates that indoor environments emit significantly higher levels of air pollutants – ranging from bacteria to volatile organic compounds (VOCs) and greenhouse gases (GHGs) – compared to outdoor environments. VOCs and GHGs, which are inevitably emitted from various household chemical products and often contain toxic properties, present a ubiquitous indoor presence. Among all indoor settings, residences are where individuals spend the most time engaging in diverse activities. Consequently, homes, while serving as shelters for relaxation, paradoxically present the highest risk for prolonged indoor exposure to various airborne hazards.

To comprehensively investigate indoor air quality (IAQ) across different types of apartments in Hong Kong, a one-year sampling measurement campaign was conducted to facilitate both overall and seasonal analyses. The comprehensive analysis revealed a strong correlation between IAQ and housing types. Higher indoor pollutant concentrations were consistently observed in public and subdivided apartments, underscoring an urgent need for increased social awareness regarding environmental health disparities in lower-income housing. To further investigate seasonal variations, three specific apartments and their microenvironments (bedrooms and kitchens) were sampled across different seasons to identify temporal correlations. The results indicated weak correlations between IAQ and seasonal changes; instead, they revealed that IAQ is predominantly dependent on occupancy rates and specific indoor activities.

Additionally, this study traced potential emission sources through targeted sampling of specific activities and household products. The findings facilitated accurate source apportionment within the three monitored apartments and successfully identified the emissions of particular compounds associated with individual activities and products. This enriches the current understanding of common residential emissions and their corresponding chemical profiles. Overall, this research presents a detailed evaluation of VOC and GHG concentrations across diverse housing types in Hong Kong (including public, private, and subdivided units) on both a general and seasonal basis, while identifying common potential indoor emission sources. These results provide a deeper understanding of the complex interactions between indoor and outdoor environments, the intricate chemistry driving IAQ, and the various influential factors. Ultimately, this work contributes foundational data for future atmospheric science research and connects these findings to broader social and public health aspects, aiming to elevate societal awareness of IAQ.