In this paper, it is shown that there are great differences in seasonal variations of concentrations of the main atmospheric pollutants in various parts of a large urban territory. The city of Krasnoyarsk is used as an example. For this, an observation method proposed by the authors is used. The detected differences in seasonal variations are a consequence of the microclimatic inhomogeneities of the city territory. They show the effects of breeze and orographic-type circulations on the space-time distribution of atmospheric pollutants. The investigation of the seasonal variability of concentrations of atmospheric pollutants in various parts of the city has made it possible to obtain some useful characteristics for the estimation of population exposure.