This publication proposes for widespread comment an extension of the existing emergency response guidance. It addresses actions based on facility conditions; preventing deterministic effects from intake; individual decontamination; immediate medical treatment; long term medical follow-up; medical consultation, especially for pregnant women following an exposure during an emergency; and implementation of protective actions under difficult conditions. This guidance also includes a plain language explanation designed to assist decision makers when making and communicating their final decision on actions to be taken, and the public. This will form the basis for future international guidance. In addition, a revised and expanded technical basis for response to nuclear and radiological emergencies is presented that is based on an examination of the latest data. This includes: (a) proposed thresholds for severe deterministic health effects for the full spectrum of important radionuclides; (b) a consensus on the insights that can be drawn from the current knowledge of the development of stochastic health effects; and (c) epidemiological and statistical considerations.