An ALOHA threat zone plot displayed on a MARPLOT map.
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.

ALOHA (Areal Locations of Hazardous Atmospheres) is a program designed to model chemical releases for emergency responders and planners. It can estimate how a toxic cloud might disperse after a chemical release and also features several fires and explosions scenarios.

ALOHA displays its estimate as a threat zone, which is an area where a hazard (such as toxicity, flammability, thermal radiation, or damaging overpressure) has exceeded a user-specified Level of Concern (LOC).

With the help of ALOHA, you can calculate how quickly chemicals are escaping from tanks, puddles (on both land and water), and gas pipelines and predict how that release rate changes over time.

The program generates a variety of scenario-specific outputs, including threat zone plots, threats at specific locations, and source strength graphs. You can then display threat zones on MARPLOT maps (and on ArcView and ArcMap with the Arc Tool extensions).

ALOHA allows you to model many release scenarios: toxic gas clouds, BLEVEs (Boiling Liquid Expanding Vapor Explosions), jet fires, vapor cloud explosions, and pool fires. Depending on the release scenario, ALOHA evaluates the corresponding type of hazard.

As part of the CAMEO software suite, ALOHA works seamlessly with the companion programs CAMEO Chemicals and MARPLOT. However, it can also be used as a standalone program.

Accessing ALOHA

ALOHA is developed jointly by NOAA and the Environmental Protection Agency (EPA), and it runs on both Mac and Windows computers.

ALOHA Program: Download ALOHA from the EPA CAMEO site.

ALOHA Examples [PDF, 1.7 MB]: Download a training document with three step-by-step fictional ALOHA example scenarios.

More Information about ALOHA

  • ALOHA Fact Sheet [PDF, 660 KB]: Learn more about program features and updates by reading this ALOHA fact sheet.
  • Ask Dr. ALOHA: Get to know ALOHA better by reading this series of informational articles that discuss key program features and walk through sample ALOHA scenarios.
  • ALOHA Arc Tools: Learn about tools for displaying ALOHA threat zones in ArcMap and ArcView.
  • Met Station Vendor List: Look through a list of vendors of portable meteorological stations designed to work with ALOHA and find out how to design a met station for ALOHA.
  • ALOHA Technical Resources: Review these documents if you are interested in developing a program or tool to work with ALOHA or if you want to learn about the equations ALOHA uses.
  • ALOHA Development History: Review a list of the most significant modifications in each release of the program.
  • CAMEO News Service: Join the CAMEO News Service e-mail list on the EPA CAMEO site to receive news and other helpful information from the development team.
  • CAMEO Software Suite: Access additional information, like training opportunities for first responders and emergency planners.

Questions: Contact us with questions, comments, or suggestions about ALOHA.