The variability of sulfur dioxide surface concentration in Moscow has been investigated. Two sources of data have been used: long-term measurements at stations of Hydro-Meteorological Service and Ministry of Health since 1957 and automatic every-minute measurements at the Ecological station of the Institute of Atmospheric Physics and the Geography Faculty of the Moscow State University for 2004-2007. During last half of century, the sulfur dioxide concentration in Moscow has been sharply reduced and became closer to its background estimations. The highest values are recorded in winter, the lowest ones - in summer and fall. The daily variation of SO2 in spring and summer is characterized by a morning maximum, probably connected with frequent raised inversions at this time. In fall, this maximum covers the daytime as well. A spread in monthly average values in winter is significantly larger in comparison with other seasons. A sharp asymmetry in mid-season conditions has been revealed (SO2 concentration is much higher in spring than in fall). A probable explanation of this effect is a large amount of precipitation in fall. Cases of anomalously high SO2 ground level concentrations, exceeding the maximum concentration limit, have been observed in Moscow very seldom, i.e., when using black oil in city heating during hard frosts in winter and, as a rule, in presence of low raised inversion at small heights (by the sodar data).