Styrene is a colorless to yellowish liquid with an aromatic, sweet odor. If styrene is not stabilizedwith an appropriate inhibitor, light or heat may promote an uncontrolled polymerization reaction, forming polystyrene. Reaction with oxygen may form a peroxide, which may explode at slightly elevated temperatures. Based on the boiling point of 145°C (293°F) and the flash point of 31°C (87.8°F), styrene is classified as a flammable liquid and vapor under the Globally Harmonized System (GHS) on classification and labeling.