Aermod Free | _hot_

| Aspect | Free Implementation | Commercial GUI | |--------|---------------------|----------------| | | Steep (manual file editing) | Shallow (interactive forms) | | Error checking | Manual (trial and error) | Automatic validation | | GIS integration | Manual (AERMAP + external GIS) | Built-in mapping | | Terrain processing | Requires separate DEM handling | Automated | | Reporting | Custom scripting needed | One-click reports | | Support | Community forums, EPA manual | Vendor support |

1. Executive Summary AERMOD is the U.S. Environmental Protection Agency’s (EPA) preferred regulatory air dispersion model for assessing pollutant concentrations from industrial sources. While commercial user interfaces exist, AERMOD itself is free —as in no cost and publicly available. This report clarifies what “AERMOD free” means, outlines the freely available components (code, executable, input processors, and output processors), and provides guidance on how to build a fully functional, legally defensible modeling system without purchasing commercial software. The report also discusses limitations and best practices for free implementations. 2. Introduction Air dispersion modeling is essential for environmental impact assessments, permitting, and compliance under the Clean Air Act. AERMOD (AMS/EPA Regulatory Model) was developed collaboratively by the American Meteorological Society and the EPA. Many users mistakenly believe that AERMOD is expensive because of popular commercial graphical user interfaces (GUIs) like Lakes Environmental’s AERMOD View or BREEZE AERMOD. However, the core model, all pre-processors, and many post-processors are distributed at no cost by the EPA . aermod free

These tools do not replace the model’s physics; they merely facilitate input generation and result visualization. While functional, a completely free implementation has drawbacks compared to commercial GUIs: | Aspect | Free Implementation | Commercial GUI

| Tool | Type | Features | |------|------|----------| | (EPA) | Free GUI | Basic file management, run control | | R-AERMOD (CRAN package) | Open source | Scripted modeling in R, statistical analysis | | PyAERMOD (Python) | Open source | Programmatic control, batch runs | | iSMART (EPA) | Free web-based | GIS integration, limited to certain uses | While commercial user interfaces exist, AERMOD itself is

| Component | Purpose | Free Source | |-----------|---------|--------------| | | Main dispersion model | EPA Support Center for Regulatory Atmospheric Modeling (SCRAM) | | AERMET | Meteorological data preprocessor | EPA SCRAM | | AERMAP | Terrain data preprocessor (uses USGS DEMs) | EPA SCRAM | | BPIPPRM | Building downwash (GEP stack height) | EPA SCRAM | | AERPLOT / AERSURFACE | Post-processing and surface characteristics | EPA SCRAM |