Welcome to BREEZE SCREEN3, for analyzing single sources in simple or complex terrain. SCREEN3 allows you to prepare an initial screening analysis to establish a conservative or worst-case estimate of short-term air quality impacts from a specific source. If predicted screening concentrations are under the level of concern, generally no further analysis is required.
Many states and EPA regions prefer this model for screening because of the wide variety of scenarios it can analyze.
Sources: SCREEN3 is designed for evaluation of a single stationary source. Point, area, and volume sources, as well as release from flares, can be analyzed.
Terrain: SCREEN3 can model flat, simple, or complex (above stack height) terrain, or a combination of simple and complex terrain.
Receptors: The model uses a program-generated distance array of receptors, user-specified discrete receptors, or both. Discrete receptors can be entered with a height above ground level (flagpole receptors), except in complex terrain.
Unique Features: An advantage of SCREEN3 over other screening models is its ability to account for the effects of building downwash. SCREEN3 is also unique among EPA models because it can incorporate the effects of inversion break-up and shoreline fumigation and can calculate concentrations in the cavity region of a building.
Meteorological Data: A matrix of 54 combinations of wind speed and stability class is included with the program. The user can also enter discrete hours of meteorological data. For complex terrain analyses, the model uses VALLEY screening conditions (2.5 m/s, F stability).