Models, Documentation, and Guidelines
In this section, section we bring you EPA's most used air quality models and guidelines. To download these files click on the filename highlighted in blue.
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| Screening Procedures |
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SCREEN3 is used to estimate maximum ground-level concentration for a single source (point, flare, area, or volume) and can be used for flat or elevated terrain.
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SCREEN3D.ZIP 73,099 bytes 9/14/95 (SCREEN3 User's Guide)
TSCREEN
Screening model for determining maximum short-term impact from toxic releases.
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VISCREEN
Initial screening model for visual impact caused by emissions to the atmosphere.
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CTSCREEN
Complex terrain screening model of CTDMPLUS.
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| Regulatory Models |
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ISCST3
Used in more detailed studies of maximum air quality impacts (Phase 3-Refined Modeling Analysis). The purpose is to compute short term concentration or deposition values, from multiple sources, on specified locations (i.e., receptors).
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ISCLT3
ISC3 Long Term dispersion model is used to model emissions with long-term averaging periods.
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CALINE3
Air quality models used to predict pollutant concentration near roadway intersections. CAL3QHC is an enhanced version of CALINE3, with the additional traffic algorithm to estimate vehicular queue lengths at intersections with traffic stop lights. We recommend that you get both models. The theoretical information regarding the CALINE3 implementation in CAL3QHC is only presented in CALINE3 User's Guide.
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CAL3QHC
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FDM (Fugitive Dust Model) is an air quality model designed for computing concentration and deposition impacts from fugitive dust sources.
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| Emergency Release Models |
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DEGADIS is a mathematical dispersion model that can be used as a refined modeling approach to estimate short-term ambient concentrations and the expected area of exposure to concentrations above specified threshold values for toxic chemical releases.
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| Related Programs |
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BPIP
BPIP (Building Profile Input Program) calculates building downwash, building heights and projected building widths, for input into ISC3 model (ISCST3 and ISCLT3).
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PCRAMMET
PCRAMMET is a very useful utility program to convert meteorological data from National Weather Service (NWS) to be used by EPA's short term air quality dispersion models such as ISCST3.
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This is a utility program that converts unformatted (binary) meteorological data files generated by the RAMMET, PCRAMMET, or MPRM preprocessor programs to the default ASCII format for applications that do not involve dry deposition.
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WRPLOT
WRPLOT is an interactive program to generate wind rose statistics and plots for user-specified date and time ranges. Wind roses are useful to define the dominant transport direction of the winds for a location.
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STAR
The STAR program summarizes National Weather Services (NWS) meteorological data, by generating joint frequencies of 6 windspeeds, 16 wind directions and 6 stability categories for the station and time period desired.
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WINDROSE
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| Modeling Guidance |
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This guideline is the regulatory document that recommends air quality modeling techniques that should be applied to different set of conditions. This document is also referred to as "Appendix W of CFR Part 51" (where CFR stands for Code of Federal Regulations).
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Supplement C to GAQM
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Screening Procedures for Estimating The Air Quality Impact of Stationary Sources
This document presents current EPA guidance on the use of screening procedures to estimate the air quality impact of stationary sources.
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