1-methylnaphthalene is a methylnaphthalene carrying a methyl substituent at position. It is a polycyclic aromatic hydrocarbon (PAH). It is present in cigarette smoke, wood smoke, tar, asphalt, and at some hazardous waste sites. The main use of 1-methylnaphthalene is as a raw material for naphthoic acid, fluorescent whitening agents, and surfactants. It is also used as a raw material for dyestuff dispersants and heat transfer oils, and as a solvent for agricultural chemical.