Revisions to the Guideline on Air Quality Models: Enhancements to the AERMOD Dispersion Modeling System and Incorporation of Approaches to Address Ozone and Fine Particulate Matter

In this action, the Environmental Protection Agency (EPA) promulgates revisions to the Guideline on Air Quality Models (‘‘Guideline’’). The Guideline provides EPA’s preferred models and other recommended techniques, as well as guidance for their use in estimating ambient concentrations of air pollutants.