Results of the field studies of mercury emission from the cyanation waste dump in the oxidation zone of the Novo-Ursk pyrite polymetallic deposit (Ursk settlement, the Kemerovo Region) are presented. Mercury content in the surface atmospheric layer above the dump surface is determined to vary within the range of 20-3600 ng/m3, while the diurnal average maximum permissible concentration (MPCd) is 300 ng/m3, thus this value is exceeded in some sites by a factor of 12. The regional background above the dump surface is exceeded by a factor of 570 on average. Comparison between the morning and evening measurement results shows that mercury concentration increases in the evening. This is due to the active emission of mercury under the action of solar radiation and heating of the dump surface. Numerical models of mercury propagation are constructed using the methods of mathematical modelling. According to the model built up on the basis of the maximal measured concentrations, the whole territory of Ursk settlement is within the zone of very high mercury vapour concentrations. Calculation over the averaged concentrations shows that the safe level is achieved at a distance of 600 m from the dump, but within the boundaries of the settlement. The obtained results provide evidence of the danger of mercury action on the population of the settlement and pose the goal of more detailed investigation of air composition over old gold mining waste storage facilities.