Road asphalt is made from aggregate (rocks) mixed with a "binder” from the residue remaining after extraction of gasoline and oils from petroleum crude oil. Until recently, this binder was thought to be chemically unreactive. Maglab scientists subjected a thin film of asphalt binder to simulated sunlight in the laboratory and used ultrahigh resolution mass spectrometry to reveal thousands of new, water-soluble chemicals that could be released into the environment by rainfall.