This report describes four studies conducted as a single phase (Phase 3B) of HEI's Advanced Collaborative Emissions Study (ACES) program, which was designed to evaluate the emissions and health changes resulting from substantially improved diesel engines required under the U.S. EPA 2007–2010 Heavy Duty Diesel Rule. These studies were conducted by Drs. Jacob D. McDonald of the Lovelace Respiratory Research Institute, Albuquerque, New Mexico, Jeffrey C. Bemis of Litron Laboratories, Rochester, New York, Lance M. Hallberg of the University of Texas Medical Branch, Galveston, Texas, and Daniel J. Conklin, University of Louisville, Kentucky.