The significant possibility that emissions of certain commercially important chemicals may deplete stratospheric ozone poses a difficult policy problem. To formulate constructive policy, it is useful to understand the many uncertainties that affect the relationship between decisions to reduce the global use of potential ozone depleters and the effects that such reduction might have on human health, materials degradation, crop yields, and other activities of interest. Only a small subset of these uncertainties are addressed here. But the relationship of these uncertainties to other parts of the policy problem provides the basic motivation. On the one hand, the complexity of the problem is so great that it must be broken into pieces if one hopes to produce useful results. On the other, the characterization of uncertainties in any part of the problem is likely to be more useful if it properly reflects the concerns of the problem as a whole. This method can be used to build scenarios relevant to one piece of the problem that relates them back to the problem as a whole.