BREEZE HAZ AFTOX, a Gaussian puff/plume model that simulates the atmospheric dispersion of neutrally buoyant chemical releases. The model was developed by the U.S. Air Force, and has been thoroughly evaluated and refined against more than 240 test cases and field studies. The model is intended for estimating concentrations downwind of accidental chemical releases, where the dispersing plume has the same density as air.
AFTOX can model the downwind concentration from several source types, including point, area, and liquid spill sources. For each source type, the release can be continuous, finite, or instantaneous in duration. If a liquid spill is being modeled, AFTOX can calculate the evaporation rate from the pool using one of three evaporation models (Vossler, Shell, or Clewell evaporation models) in addition to providing the downwind plume concentrations.
For each release, AFTOX assumes the plume distribution is Gaussian in the downwind and crosswind directions. The model uses Pasquill-Gifford dispersion coefficients, with modifications to account for a user-specified averaging time.
BREEZE HAZ AFTOX offers many features to tailor your analyses to a wide variety of sources and release scenarios.
Release Scenarios... models a variety of release scenarios, including: point, area, and liquid spill sources.
Receptors... calculates plume concentration at model-selected downwind receptor distances.
Chemical Property Data... contains a database of over 150+ common industrial chemicals. The program includes the capability to add and store new chemicals or modify existing chemical data.
Toxicity Data... includes chemical toxicity data, including the Toxic Endpoint, IDLH (Immediately Dangerous to Life and Health), TLV-TWA (Threshold Limit Value - Time Weighted Average), and TLV-STEL (Threshold Limit Value - Short Term Exposure Limit) values, where available, for each chemical.
Meteorological Data... estimates stability class using site characteristics, date and time of release, and user-specified cloud cover, cloud type, and wind speed observations or the stability class can be entered directly. The model simulates one set of meteorological conditions, and is applicable for averaging periods of 1-hour or less.