Strategies for reducing exposure to ragweed pollen are given a quantitative basis on the relationship between the distributions of ambient air ragweed pollen, its sources, and the urban population. Avoidance of a major fraction of the seasonal dosage is possible at little cost, particularly if the influences of day-to-day weather changes on the pollen count are known. Techniques are presented for estimating both the likely day-to-day pollen count and the influence of avoidance time patterns on dosage. Through a mathematical optimization method, the avoidance strategies can be made more efficient and uncertainties in the dosage reduction they are likely to achieve can be reduced. Ragweed plant control, however optimally carried out, is economically impractical here at the levels required to significantly reduce urban pollen counts. A public health program giving the pollen count effective meaning is described based on these findings.