Pyrene is a polycyclic aromatic hydrocarbon (PAH) composed of four fused benzene rings. It has a distinct aromatic odor, produced by incomplete combustion of organic matter. Pyrene exhibits strong fluorescence, emitting in the blue region of the spectrum, making it useful as a probe for studying molecular interactions in solution and on surfaces. Pyrene is also used as a model compound for the study of PAHs in various environments and biological systems because of its ubiquity in these environments. However, long-term exposure to pyrene has been associated with potential health risks, including carcinogenicity and mutagenicity.