The Development and Applications of an Improved Model for Indoor Air Chemistry

The need for good indoor air quality is imperative for healthy living. In recent years, computational models have become an important tool to aid understanding of the chemical transformations which arise following emissions of pollutants from indoor sources. Models are particularly helpful where there are experimental or logistical challenges determining the concentrations of indoor species. The aims of this thesis are, therefore, to develop and improve a detailed indoor air chemical model focusing on three key elements: indoor surfaces, indoor-outdoor exchange, and air cleaning, so developing improved understanding their impacts on indoor air quality. Modelling results showed that surface emissions were important indoors, both through formation of secondary pollutants following surface oxidation, and through influencing indoor air pollutant concentrations depending on the surface composition within a room. For instance, total secondary pollutant concentrations were found to be 6.7 ppb in a kitchen, 4.8 ppb in an office and 5.8 ppb in a bedroom. Through investigation of the impact of indoor activities on outdoor air, ventilation rates and timing and frequency of cooking and cleaning controlled the emissions of volatile organic compounds from indoors to outdoors. Total emissions following these activities were estimated to be approximately 29% of those released from traffic in the UK. Elevated ozone and radical concentrations followed simulated use of a far-UVC air cleaning device using light between 220 and 230 nm. Ozone and OH radical concentrations reached 30.3 ppb and 2.3 × 10^5 molecule cm^−3 respectively, approximately 1200 and 500% above baseline values, perturbing the subsequent chemistry. This thesis contributes to an improved understanding of indoor air chemistry through the development and use of a detailed chemical model. As outdoor air quality continues to improve in the future, indoor sources of pollution will play an increasing role in our exposure to air pollution both indoors and outdoors.