INTRODUCTION AND OUTLINE OF FUTURE EFFORT The recent acute Interest in atmospheric hazes and associated aspects of air pollution reflects a general awareness of the threat of diminishing air resources. Because of the complexity of the problem which involves industrial@ scientific@ and biological@ as well as social aspects@ there Is great dispersion of literature between these and other disciplines. In preparing this review we did not@ therefore@ aim at reviewing all the relevant publications; rather@ the method was to identify the most important trends of haze research and to follow the development along these trends. Most leading experts agree that the present state-of-the-art in haze research does not allow immediate formulation of a complete system for classifying and identifying various types of atmospheric haze. A further series of both laboratory and field studies appears necessary. If in the laboratory there is a tendency to consider simple systems which may not be readily relatable to the atmosphere@ the object of field surveys@ especially in urban regions@ is so complex that the field studies rarely yield conclusive results. In view of this@ the greatest importance should be attached to planning comprehensive complexes of identification measurements (combination of detailed direct analysis of aerosol samples with the scattering and transparency measurements@ inclusion of the angular scanning techniques@ polarization measurements@ etc.).