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Air pollution is predominantly an urban problem affecting residents living in or around cities. According to the 2014 report of the World Health Organization (WHO), air pollution is now the world’s largest single environmental health risk (WHO 2016). This problem is exacerbated by rapid global population growth (Wania, Bruse et al. 2012), and densely populated urban areas are hotspots of this high risk due to outdoor air pollutant exposure, which also affects indoor air quality. Despite the advancements in urban policies necessary for curtailing air pollutant emissions, it is vital to adopt appropriate strategies in urban planning to manage and reduce outdoor air pollution to minimise the negative impact on public health (Li, Shi et al. 2020). Natural ventilation in the built environment is associated with enhancing outdoor and indoor air quality due to its air pollutant mitigation capacity (Li, Ming et al. 2021). Therefore, natural ventilation capacity deserves special attention from a fundamental perspective, resulting in novel solutions for combating this global problem. This research project focuses on the underlying wind-structure interaction mechanisms involved in the air pollutant dispersion process around buildings. The effect of building cross-section shape and air pollutant density are investigated, and a new fundamental concept of air pollutant emission regions is introduced. The effect of building cross-section shape is further investigated in an idealised generic building cluster based on the fundamental flow structure. Additionally, mean and transient features of air pollutant dispersion based on both continuous air pollutant emission and stagnant air pollutants around a generic isolated building are explored in detail. Finally, two new indices based on air pollutant exposure time in a scaled model are proposed to capture full-scale air pollutant time integrated with air pollutant concentration.