PREFACE This report presents the findings of a two- year investigation of the effects of carboxyhemoglobin (expressed as percent of hemoglobin combined with carbon monoxide) on human performance@ particularly in regard to the task of driving an automobile. This study was performed under contract to the Coordinating Research Council and was financially supported by the U.S. Environmental Protection Agency@ the American Petroleum Industry@ and the Motor Vehicle Manufacturers Association. The scope of this study includes three major objectives: 1. The development of methods for rapid and accurate laboratory and field measurement of carboxyhemoglobin (COHb) in man. 2. The determination of the effects of up to 20% COHb concentrations on a. physiological performance@ b. complex psychophysiological and psychomotor skills@ and c. driving skills and judgment on the highway. 3. The determination of the predictability of decrement in driving skills based upon laboratory skills testing. The opinions@ findings@ and conclusions in this publication are those of the authors and not necessarily those of the sponsors.