Evaluating Population Exposure to Indoor Volatile Organic Compounds

Volatile organic compounds (VOCs) are a major source of air pollution with diverse indoor emission sources. Poor ventilation, solvent-containing products, and personal behaviours can elevate indoor VOC levels, though real-world data is limited. This thesis examines indoor VOC dynamics, focusing on emissions from household products and real-home exposure. Using a state-of-the-art gas chromatograph mass spectrometer, VOCs at sub-part per billion levels were identified and quantified alongside building characteristics such as age, and air change rates (ACR), as well as occupant activities such as cooking and cleaning times and frequency. In the first experiment, VOC emissions from liquid electrical (LE) fragrance diffusers were measured in 60 homes. Homes with the lowest ACR had the highest exposure to VOCs originating from LEs. A controlled booth experiment showed that monoterpene emissions from up to five LEs in a 10 m\textsuperscript{3} booth were below their theoretical odour detection threshold. Moderating monoterpene content in fragrances could reduce formation of secondary air pollutants without affecting scent perception. It is possible that excessive off-label product use may be self-limiting as perceived fragrance intensity plateaued beyond two LEs operating simultaneously. A third study measured VOC concentrations in 124 homes in Bradford, UK over 12 months (2023–2024). Urban homes exhibited higher benzene, toluene, ethylbenzene and xylene (BTEX) concentrations due to outdoor pollution ingress. Acetaldehyde and carbon tetrachloride concentrations frequently exceeded lifetime cancer risk benchmarks. Scaling VOC concentrations to room volume and ACR into time-integrated emission rates revealed a seasonal trend, with rates generally peaking in summer and dipping in winter. A final chapter details a developed method to assess VOC emissions from aerosol products via gas chromatography, allowing for the analysis of potential product contamination, as well as identifying solutions to improve sampling rigour. This thesis advances understanding of indoor VOC sources, accumulation, and exposure in homes, providing contemporary real-home data to inform future research and improve indoor air quality models.