Abstract: Recent frequent power outages of a 400/132 kVA substation near Al-Diwaniyah city coincided with an expansion of the brick industry in the same area have called for extensive study to investigate the probable effect of stack emission from brick factories on the occurrence of high voltage insulator flashover. Experimental and theoretical investigations have been conducted to predict the dispersion and deposition of Particulate Matters (PM) released from the neighboring brick factories within the area of study. Measurements of relevant airborne pollutants; Carbon dioxide (CO₂), Volatile Organic Carbon (VOC), Total Organic Carbon (TOC) and PM at 2000 m from the boundary of the brick factories were taken in the opposite direction of the prevailing wind (upwind location) and considered as reference readings. Downwind measurements were taken each 250 m from the boundary of the brick factories up to the 400/132 kVA substation. Meteorological data were measured to evaluate its effect on the dispersion and deposition rates of PM. The Gaussian dispersion model was adopted to simulate the local air pollution and the characteristic distance for PM was determined. Obtained results show that atmospheric stability conditions play a major role in determining the values of the dispersion and deposition rates of PM on the surface of the high voltage insulators and consequently the occurrence of flashover during wet atmospheric conditions (fog and mist). Deposited layer thickness varies in order of magnitudes when atmospheric stability changes from moderate unstable conditions (class B) to stable conditions (class F).