<p>This article is devoted to the problem of the propagation of harmful pollutants in the atmosphere from point sources taking into account photochemical transformations. A complete list of typical atmospheric pollutants of the industrial city was determined. The fifteen most common types of harmful substances such as NO<sub>2</sub> (nitrogen dioxide), H<sub>2</sub>SO<sub>4</sub> (sulfuric acid) to examine the transformation of impurities were selected. A scheme for the conversion of pollutants by chemical reactions was created. The transfer process and the transformation of substances were described by a system of differential equations. The resulting differential equations are constructed on the basis of stoichiometric formulas and the constant of reaction rate in accordance with the law of mass conservation. To account for the influence of anthropogenic heat sources and heterogeneity of the underlying surface on the propagation of harmful substances taking into photochemical reactions, a model of atmospheric boundary layer and the transport equation and transformation of pollutants by the example of the city of Ust-Kamenogorsk was considered. The schemes of stable and convergent difference for the equations of the atmospheric boundary layer and transport and transformation of admixture of harmful substances were designed. A software package for numerical simulation of air pollution taking into account photochemical transformations and corresponding visualization of scenarios was developed. The software package allows simulating the spread of pollutants under different weather conditions. The results of the daily monitoring of distribution and dynamics of the formation of chemical substances were obtained. The results of numerical simulation of the propagation and transformation of harmful impurities on mesometeorological background processes taking into account the terrain and water surfaces were presented. The analysis of the propagation of the substance concentration taking into the transformation of harmful substances of components was carried out. The results show that the description of photochemical reactions in the mathematical model proposed in this paper allows identifying areas which are heavily contaminated with salts such as MgSO<sub>4</sub>, CaSO<sub>4</sub> and acids of H<sub>2</sub>SO<sub>4</sub> with a reasonable accuracy due to the sequantial chemical reactions taking place in the atmosphere.</p>
Numerical simulation of particle transport in the urban boundary layer with implications for SARS-CoV-2 virion distribution
