Densely compressed, decayed vegetation cut from bogs and dried, then used in the malting process as a smoke-producing fuel that both dries the barley and imparts a distinct flavor. Peat smoke is used in the production of certain Scotch whiskies, including many from Islay. It is used in the production of some whiskies from other countries as well, including Ireland, India, Japan, and the United States. Levels of “peatiness” in whisky are measured in phenol parts per million, or PPM.