During single particle analysis of aerosol in Kraków (Poland) we noticed a new component, that is, aggregates of TiO2 particles. These aggregates are from 0.5 to 4 μm and are composed of individual particles whose size typically varies from between 100 and 350 nm. Smaller particles (below 100 nm) also occur. TiO2 particles are relatively abundant in the summer. The size distribution of the particles corresponds to “pigmentary” TiO2, which indicates that they could be derived from paints and building materials. TiO2 particles were not previously identified in aerosol samples in Kraków, and therefore this phenomenon is likely to be related to the common usage of new building materials and paints. A review of the literature suggests that TiO2 particles, especially within the nanosize range, could result in health and environmental impacts; however, evaluation of the actual threat is difficult.