The primary purpose of the study described in this report was to test the performance of the gravitational settling/dry deposition of the Industrial Source Complex (ISC) Dispersion Model using the 1980 particulate air quality measurements made by Armco and EPA in the vicinity of the Armco Steel Mill at Middletown, Ohio, with the corresponding Armco emissions data. Statistical comparisons of calculated and observed concentrations, made following the procedures suggested by an AMS Workshop on Dispersion Model Performance, show that use of the ISC Model's gravitational settling/dry deposition option yields calculated total suspended particulate concentrations in closer agreement with the observed air quality than the corresponding concentrations calculated by the model without using this option. Because the particulate concentrations calculated by the ISC Model without using this option are representative of the concentrations that would be calculated using the modeling techniques recommended for application to particulate sources in the current (April 1978) EPA Guideline on Air Quality Models, the results of the study indicate that the ISC Model with the gravitational settling/dry deposition option is an improvement over the modeling techniques currently recommended for particulate sources.

"H.E. Cramer Company, Inc." "February 1982." Includes bibliographical references (pages 155-157). "EPA-450/4-82-006." "EPA contract no. 68-02-3323, work assignment no. 8."