The work presents the general requirements for the control of emissions to air from waste co-combustion (co-incineration) plants, with particular emphasis on rotary kilns used for clinker production. Air emissions from the cement kiln during co-combustion of alternative fuels and the impact assessment on air quality are also presented. The object of the study was one of the Polish cement plant, which uses significant amounts of solid waste derived fuels (with over 70% share in the cement kiln heat balance). Assessment of the impact on air quality was made based on the results of the modeling of atmospheric dispersion of selected pollutants. The relatively most burdensome was considered the emission of NOx, which, however, does not cause significant air pollution (not exceeding of permitted levels).