Boilers working with light oil are popular in Polish heating systems and the amount of pollutants emitted during their work should be controlled. This paper shows the impact of nozzle parameters on pollutant emissions. The tests were conducted on a typical low-power burner used in houses and small public buildings. The pollution measurements were done for several oil nozzles fitting to a burner in the range of oil pressure from 0.8 to 1.5 MPa. The results show the high impact of oil pressure and nozzle type on the fuel combustion process and pollutant amounts, although the boiler’s thermal capacity is constant. Carbon monoxide emissions for the oil pressure from 1.0 to 1.35 MPa was low, although the average values in ranges of oil pressure from 0.8 to 1.0 MPa and from1.35 to 1.5 MPa for some nozzles was too high (330-2000 ppm).