Given both mobile and fixed sources of pollution, the number of feasible strategies for meeting regional air-quality standards becomes so vast that it is impractical to evaluate all of them in terms of detailed impacts. To aid in this process, the computer-based tradeoff model has been developed to evaluate alternative strategies, select superior strategies for further evaluation, and analyze the sensitivity of results to key assumptions. Given a fixed-source control strategy, a menu of retrofit-inspection/maintenance strategies, and a menu of transportation management strategies, the tradeoff model finds the best combination--i.e., the superior strategy--and calculates a variety of impacts. The best combination is defined as the one that meets the desired air-quality standard for the minimum value of the total-cost proxy, where this proxy includes both the net expenditure for strategy components and the monetary proxy for the social cost of forgone travel. 79 pp. Ref.