OLM for BEEST for Windows


The ISC3_OLM Model was developed by the ARM/OLM Workgroup* as an alternative to the Ambient Ratio Method (ARM) for the prediction of annual and short term nitrogen dioxide (NO2) impacts. The Model incorporates the Tier 3 screening level analysis procedures of the Ozone Limiting Method (OLM) contained in the 1986 Guideline on Air Quality Models (Revised). In addition, the Model has incorporated two features inherent in the OLM procedures. They are the differences in molecular weight of ozone (O3) and NO2, and the option to calculate NO2 from individual or combined plumes. See the Use of the Ozone Limiting Method for Estimating Nitrogen Dioxide Concentrations draft guidance document for details.

The Model can be executed in either a refined mode using hourly sequential meteorology, or in a screening mode utilizing user generated meteorology and O3. The user should be aware that the meteorological data file and the O3 data file should have matching dates (i.e. year, month, day and hour). An example of a screening meteorological data set is the SCREEN3 54 wind speed and stability combinations.

Since this model is a non-guideline model, the ARM/OLM Workgroup recommends that the permitting agency be contacted to obtain approval for its use in an air permit application.