In the paper, an assessment of the compliance with air emission limit values and the impact on air quality of one of the largest medical waste incinerators in Poland, with a total capacity of about 300 kg/h (two incineration lines) is presented. The assessment took the results of continuous and periodic measurements of emissions in the plant’s installation over a period of 12 months’ operation into account. For this period, a calculation was performed for the spread of air pollutants emitted by the two operating incineration lines. According to the analysis and calculations, the analysed medical waste incineration plant does not significantly affect air quality. For the location of such facilities in the urban area, an adequate distance from residential buildings is, however, desirable to reduce the risk of elevated concentrations of certain substances in air (especially NO2).