Intervention Levels 4 : Levels of radiation or concentrations of chemicals in the environment. These levels determine the measures to be taken in the measure zone and can be regarded as aids to decision-making
By M. Debacker, B. Domres, Walter Hays, J. de Boer, Prehospital and Disaster Medicine, Disaster Terminology, Glossary of New Concepts in Disaster Medicine, USA 2002, http://www.eird.org/isdr-biblio/PDF/Prehospital%20 and%20disaster%20medicine.pdf, (D/DM - Amer) {831}