E-MAPS uses the EPA's ALOHA model to provide users the ability to simulate plume models.  Once a plume model has been created, its foot print is displayed on the map as an Event.  The user can then use the plume model in order to perform other analysis such as population impact assessment or evacuation planning.

ALOHA (Areal Locations of Hazardous Atmospheres) is a computer program designed especially for use by people responding to chemical accidents, as well as for emergency planning and training.  ALOHA can predict the rates at which chemical vapors may escape into the atmosphere from broken gas pipes,leaking tanks,and evaporating puddles.  It can then predict how a hazardous gas cloud might disperse in the atmosphere after an accidental chemical release.

ALOHA runs quickly on small computers that are easily transportable. It is designed to be easy to use so that you can operate it successfully during high-pressure situations.  Its chemical library contains information about the physical properties of about 1,000 common hazardous chemicals.  Its computations represent a compromise between accuracy and speed: it has been designed to produce good results quickly enough to be of use to responders.  

ALOHA is designed to minimize operator error.  It checks information that you enter and warns you when you make a mistake.  ALOHA ’s online help offers you quick access to explanations of ALOHA ’s features and computations,as well as background information to help you interpret its output.