The only Polish municipal solid waste (MSW) incinerator has been operating within the Municipal Solid Waste Disposal Plant in Warsaw since 2000. In the paper selected results of the air quality impact assessment for this incinerator during an operating period of one year (2008) are presented. With respect to the incinerated waste amounts and emission levels, the analysed period can be considered typical for this facility. Assessment of the air quality impact was carried out by assessing air pollutant emissions in reference to the applicable emission limit values and by modeling atmospheric dispersion of these pollutants. It has been found that the MSW incineration plant in Warsaw is an insignificant air pollutant source and causes slight air pollution within its impact range. Pollutant concentrations caused in the atmosphere are many times lower than the permissible substance levels and reference values valid for a given substance. Planned as a result of the expansion of the incineration plant, the increase in its processing capacity while continuing to meet the emission standards should also not cause a significant impact on air quality.