Explainer Video -- FEMA IMAAC Early Phase Products

Video Narration


Explainer video for products made available by FEMA's IMAAC division

Vocal Characteristics



Voice Age

Middle Aged (35-54)


North American (General) North American (US General American - GenAM)


Note: Transcripts are generated using speech recognition software and may contain errors.
things to know about Early phase products. In the early phase of a radiological incident, the primary protective actions that decision makers may recommend are sheltering in place or evacuation of the public imac produces several early phase products that provide helpful information to decision makers. In the early phase of a radiological incident. To default products, identify areas that may exceed the protective action guides for sheltering in place or evacuation of the public. One is the early phase total effective dose plot which includes dose from the airborne radioactive plume and the other is the early phase avoidable dose plot, which does not include dose from the airborne radioactive plume if it has left the area before the time period shown, these are often called the total dose and the avoidable dose plots and are also distinguishable by the time periods listed in their titles, Either 0- 96 hours or 12- 108 hours respectively. Total dose plots are generated by modeling the dispersion of the released radioactive material and summing up the dose that would be received during the default early phase of four days. The total effective dose is calculated by summing up doses received by four pathways. External dose received from the airborne plume. Internal dose received by inhalation of materials from the airborne plume. External dose received from ground shine deposited on the surface and internal dose received by inhalation of re suspended ground deposition, Avoidable dose plots are generated by the same process but the default four day calculation starts 12 hours after the incident begins. In most cases, this means only the ground shine and re suspension dose pathways are included in the dose summation for these early phase products, the yellow contoured area will depict the one rem protective action guides or paige for evacuation or sheltering in place. While the smaller orange contoured area will depict the higher five rem paige. These dose levels come from the Environmental Protection Agency or E. P. A paige manual, which gives the early phase paige as a range of 1 to 5 rem projected dose depending on the incident circumstances. For the same plume model simulation, the avoidable dose contours will be smaller than the total dose contours because the dose received in the 1st 12 hours is not included in the summation. The E. P. A paige manual advises that public protection decisions should be based on the avoidable dose and that doses incurred before the start of the protective action being considered generally should not be included in evaluating the need for protective action. However, in some scenarios there may be advanced warning that a release will occur sometime in the future and so the total dose from the start of the release may be considered avoidable projected doses are estimated based on standardized methods that are detailed in the assessment manuals developed by the federal radiological monitoring and assessment center or for MAC. These technical manuals provide standard assumptions that are used in the initial response to an incident. Before details are known as more information becomes available. Model calculations may be revised for improved accuracy, which may result in updated model products with differences from the initial default set. For further information on the various imac products for a radiological or nuclear incident, please see our other training videos and visit fema dot gov slash imac.