The sustainable development of public transport is inseparable from its key elements, transport. In recent years, reflections on green public transport have been steadily intensifying and setting new guidelines for its development focused on the environment. Gas-powered, more environmentally friendly diesel buses are used for this purpose. Part of such a transport fleet in Vilnius consists of such buses. Pollution from mobile sources is predominant in cities, so particulate matter from different gas buses (powered by CNG) was identified in this study. In this study, particle concentration measurements were performed, in which the dependence of the particle concentration on the mileage of the buses was determined.