Outgassing (sometimes called offgassing, particularly when in reference to indoor air quality)'s the slow release of a gas that was trapped, frozen, absorbed or adsorbed in some material. It can include sublimation and evaporation which are phase transitions of a substance into a gas, as well as desorption, seepage from cracks or internal volumes and gaseous products of slow chemical reactions. Boiling's generally thought of as a separate phenomenon from outgassing because it occurs much more r… (More on Outgassing)