A concentration of airborne contaminants, normally expressed in parts per million (ppm) or milligrams per cubic meter, that represents the maximum level from which one could escape within 30 minutes without any escape impairing symptoms or irreversible health effects [nfpa 55, 2016].
A cargo which the consignee nation regards as essential for the prosecution of a war or for national survival, to be delivered immediately, notwithstanding any risk to the ship or its crew.
