The aim of the project is to prepare a source apportionment for nitrogen oxides (NOx), nitrogen dioxide (NO2), PM10 (particles less than 10 microns) and PM2.5 (particles less than 2.5 microns) and number of particles for urban background concentrations and street concentrations in Copenhagen to estimate how much the different sources contribute. The source apportionment will show how much the different sources contribute to the concentration, respectively, for urban background and street concentrations (in micrograms per cubic meter and in percentage). The focus of the project is on air pollutants that are harmful to public health. Carried for Municipality of Copenhagen. Project period 5. Januar to 1 June 2013.