Polycyclic aromatic hydrocarbons (PAH) are important in combustion processes from two points of view: As precursors for soot formation and as pollutants, if they are emitted. Usually PAHs are measured by GC-MS or HPLC analysis of filter extracts, which is a time and cost intensive procedure and does not allow on-line measurements. An alternative is photoelectric charging of particles by irradiation with ultraviolet light. If an appropriate wavelength is chosen, the emission probability of electrons mainly depends on the amount of particle bound PAHs. This allows a simple and fast monitoring of PAHs in emission and ambient air measurements. Here the application of this method to measure particle bound PAHs in the exhaust of different combustion systems (oil burner, combustion engines) is discussed.