ABSTRACT
Polycyclic aromatic hydrocarbons (PAH) consist of three or more benzene rings interlinked in various arrangements. The entire group of PAH can be divided into kata-annellated and peri-condensed systems. The physical and spectroscopic properties of PAH are dominated by the size and topology of the π-electron system. The extended π-electron system of PAH leads to strong absorption of visible or ultraviolet (UV) radiation which gives characteristic absorption and fluorescence spectra. A number of studies have been reported relating to the distribution of atmospheric PAH with respect to particle size. Some information is available on the relationship of PAH to particle size, and this has particular significance with respect to the entry of PAH into the respiratory tract, and the deposition and retention in the organism. Reactions of PAH appear to play a major role in the removal of PAH from the atmosphere.
