See Also
Air
Quality Permitting
in Idaho
Learn more about
air permit requirements
Workshops
Contact DEQ
Regional
Office
Air Quality Managers
State
Office
Air Quality Division
Mary Anderson
(208)
373-0202
Kevin
Schilling
(208)
373-0122
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Air Quality: Modeling
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Air quality dispersion modeling is used to estimate
concentrations of pollutants that new (or existing) emissions sources
may emit. Examples of emissions sources include stack emissions from
industry and areawide emissions from groups of sources such as automobiles
or wood stoves. Computer programs are used to make these estimates.
Air modeling is required by the state of Idaho to demonstrate compliance
with the National Ambient Air Quality Standards (NAAQS), toxic air
pollutant (TAP) standards, and Prevention of Significant Deterioration
(PSD) increments. |
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| Modeling and Permitting |
Air
modeling is required for certain permitting actions to demonstrate
that all applicable ambient air quality standards will be met if
a proposed construction or modification to a facility is completed
or that an existing facility is complying with the standards.
Permitting
actions that generally require air modeling include:
- Permits to construct
- Permit to construct exemptions
- Tier II operating permits
(Note:
Most exemptions from permits to construct also require the facility
to demonstrate compliance with the NAAQS.)
The air modeling must
demonstrate compliance with all appropriate rules and regulations.
If the modeling shows that construction or modification would cause
or significantly contribute to a violation of an ambient air quality
standard, result in an impact above applicable PSD increment limits,
or have a significant impact in a Class I or a nonattainment area,
DEQ cannot issue a permit for the proposed facility. To proceed,
the facility's permit application needs to be revised and additional
modeling performed.
What
is a Class I area?
What
is a nonattainment area? |
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| Idaho's Modeling Guideline |
| To assist air permit applicants, air
quality specialists, and others understand DEQ’s expectations
for ambient air impact analysis, DEQ has developed the State
of Idaho Air Quality Modeling Guideline (DEQ
Publication, December 2002: pdf 390 kb, 66 pages). The guideline
explains in detail when modeling is required; outlines applicable
standards, methodology, and analysis; and provides checklists and
templates for conducting modeling and reporting modeling results.
Use DEQ's guideline in conjunction with the federal EPA's
Guideline on Air Quality Models (2003 Edition
of 40 CFR 51, Appendix W) and EPA's
1990 New Source Review Workshop Manual to help expedite DEQ’s
review of your permit application. |
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| For More Information |
EPA Modeling Web Sites |
Air
Quality Modeling
Link to various EPA Web sites that contribute to federal air quality
modeling efforts.
Support
Center for Regulatory Air Models (SCRAM)
Find out about mathematical models used to predict the dispersion
of air pollution. The site includes computer codes, meteorological
input data, documentation, and guidance on usage. Its primary purpose
is to provide air pollution control agencies with air quality models
and related information that support selected requirements of the
Clean Air Act. |
Meteorological Data |
Surface
Meteorological Data compiled by the National Weather Service
National Climatic
Data Center
Idaho State Climate
Services
National Weather Service
Forecast Office – Missoula, MT |
Topographical Data |
U.S.
Census Bureau TIGER database |
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