We present data on dynamics of the ion composition of atmospheric aerosols during the period from 1996 until 2004 for four observation sites in the Western Siberia differing in natural climatic conditions and in industrial load. Two groups of ions formed from volatile and nonvolatile precursors are distinguished in the aerosol composition. Factors determining the seasonal and spatial concentration variability of the first group of ions are common for all sites and have a regional nature. For the second group of ions, their action depends on local conditions. The ratio between the contributions of ions from both of these groups determines also the level of the aerosol acidity. Influence of industrial sources of the big center (Novosibirsk) on the ion composition of aerosols is discussed in this paper.