Method of treatment of biological surfaces

Method of treating biological surfaces with electromagnetic radiation in the form of light of two different energy levels, a first light with photons having a majority energy in the range from 3.5 eV to 2.8 eV and a second light with photons having a majority energy in the range from 1.24 eV to 2.48 eV. The photons of the first light and the second light are simultaneously directed against the biological surface. The invention also contemplates the use of sensitizers in topical treatments of infections using the method. The treatment will achieve good tissue penetration. It makes it possible to give antibacterial treatment to different areas of pathogen at the same time as two or more different energy photons can target molecules in different areas.