INTRODUCTION The purpose of this study was to construct dose/effect profiles for acute sulfur dioxide and nitrogen dioxide health effects utilizing data from controlled human exposure studies. Since for both pollutants the data base is diverse@ the scope of this study was specifically limited to studies assessing acute increases in airway resistance in normal subjects at rest. The decision to initially utilize changes in airway resistance arose out of several factors. Firstly@ because it is an effect which is rapid in onset and appears to be readily reversible thereby eliminating the necessity to introduce analyses of lag effects at the early stages of the effort. Secondly@ because current scientific evidence dictates a need to gather health intelligence on such acute phenomena for these pollutants. Additionally@ at present the U.S. EPA is considering adoption of short-term standards (1-3 hour range) for SO2 and NO2 based on health protection. In its consideration the Agency is leaning toward a reliance on data derived from controlled human exposure studies which assess changes In airway resistance (Raw) or its converse: airway conductance (Gaw)@