An unplanned demolition of a building can be a result of either natural e.g. earthquake or human-made disaster e.g. terrorist attack and wars. It generates considerable amount of coarse, fine and ultrafine Particulate Matter, which are significantly associated with chronic and acute adverse health effects. Literature study attributed to few studies about the impact of planned demolition on local air quality, while the short-term bursts of pollutants and public exposure to this high pollution levels during an unplanned demolition were widely overlooked. Meanwhile, the existing research has also pointed out that the characteristics of the pollutant dispersion are highly dependent on the urban morphology. The primary objective of this research is to investigate the pattern and characteristics of pollution dispersion due to unplanned building demolition in a compact high-rise/ low rise and open high-rise/ low rise neighborhood. CFD-based microscale air quality model “ENVI-met” was used to simulate the pollution dispersion in the selected morphologies. The pollution concentration was measured at the various horizontal and vertical distance at various times and wind directions (0 and 315 deg). Thirty-six different measurement from horizontal dispersion and forty-eight different measurements from vertical dispersion for PM concentration and wind speed were measured and tabulated. LEONARDO was used to visualize the output in ENVI_met binary files and Microsoft Excel was used to plot the graphs showing a summary of relationship between the tested parameters. The results indicated that the pollution dispersion pattern depended on its neighborhood morphology which is represented by its street canyon and building height, wind flow and vegetations. These findings are followed by the design recommendations based on the observation of pollution dispersion pattern in different morphologies while suggesting a need of air quality standards for short term high pollution levels.