ALOHA (Areal Locations of Hazardous Atmospheres) is a modeling program that estimates threat zones associated with hazardous chemical releases, including toxic gas clouds, fires, and explosions. A threat zone is an area where a hazard (such as toxicity, flammability, thermal radiation, or damaging overpressure) has exceeded a user-specified Level of Concern (LOC).
An ALOHA threat zone plot displayed on a MARPLOT map. The red, orange, and yellow zones indicate areas where specific Level of Concern thresholds were exceeded.
· Generates a variety of scenario-specific output, including threat zone plots, threat at specific locations, and source strength graphs.
· Calculates the rate of release for chemicals escaping from tanks, puddles (on both land and water), and gas pipelines and predicts how that release rate changes over time.
· Models many release scenarios: toxic gas clouds, BLEVEs (Boiling Liquid Expanding Vapor Explosions), jet fires, vapor cloud explosions, and pool fires.
· Evaluates different types of hazard (depending on the release scenario): toxicity, flammability, thermal radiation, and overpressure.
· Displays threat zones on MARPLOT maps (and on ArcView and ArcMap with the Arc Tool extensions)
· Works seamlessly with companion programs CAMEO and MARPLOT; it can also be used as a standalone program.
ALOHA was developed jointly by NOAA and the Environmental Protection Agency (EPA), and it runs on both Macintosh and Windows computers. Download the programme and manual from:
or here: ALOHA Manual.pdf [2 MB].
Read the manual and become familiar with the programme. Use ALOHA to model a chlorine release from a water treatment facility. Find out what quantities of chorine are stored at your local water treatment facility and determine the area that would be affected if a one tonne quantity of chlorine gas was accidentally released. (Use average meteorological conditions for your locality).