Existing methods for calculating the emission rates of primary pollutants from cars are analyzed from the position of the predominance of their various emission standards in the traffic flow. These masses of substances per unit time are used in further calculations of the concentration fields of these compounds obtained during the study of dispersion processes. Emissions are considered at various flow densities and vehicle speeds during continuous movement, as well as in the area of a pedestrian crossing equipped with a traffic light. In this case, the concentrations of nitrogen oxides and reduced carbon compounds, as well as their ratios, change over a fairly wide range. The content of a more toxic secondary pollutant, ozone, is determined using the proposed mathematical model. It is built on the basis of a stiff system of differential equations, reflecting the kinetics of this process and solved by the Rosenbrock method. During numerical experiments, a search is made for the best and worst options in terms of impact on the atmosphere.