Applicants for major modifications or for major sources of criteria air pollutants in an attainment or
unclassified area must perform air quality dispersion modeling under the Prevention of Significant
Deterioration (PSD) program. Also, under certain circumstances, minor sources of air pollutants may be
required to model. Sources use the air dispersion model to predict the ground level impact, in terms of
concentration of a particular pollutant, for comparison to a standard.
As part of the Clean Air Act, Federal Land Managers have an affirmative responsibility to protect the
natural and cultural resources of Class I areas from the adverse impacts of air pollution. Federal Class I
areas are defined in the Clean Air Act as national parks over 6,000 acres and wilderness areas and memorial
parks over 5,000 acres, established as of 1977. All other federally managed areas are designed as Class II.
The Federal Land Managers' Quality Related Values Work Group (FLAG) was formed to develop a more consistent
approach for the Federal Land Managers (FLM's) to evaluate air pollution effects on their resources. Of
particular importance is the New Source Review (NSR) program, especially in the review of PSD air quality
permit applications. The goals of FLAG are to provide consistent policies and procedures both for
identifying air quality related values (AQRV's) and for evaluating the effects of air pollution on AQRVs,
primarily those in Federal Class I areas, but in some instances, in Class II areas. The AQRVs that are
studied for PSD permits are: visibility, regional and direct plume impaction, and deposition. Air quality
modeling is used to predict impacts of a proposed source for comparison to National Ambient Air Quality
Standards (NAAQS), PSD standards, and AQRV target values.
The Class I areas in West Virginia are Otter Creek and Dolly Sods.