Sulfur dioxide, total suspended particulates and, to some extent, nitrogen dioxide are appropriately classified as nonuniformly mixed assimilative pollutants.1 If the resulting allocation of control responsibility for these pollutants is to be cost effective, the theory reviewed in chapter 2 is convincing on the need for control authorities to consider where the pollutants are injected into the air as well as how much. Unfortunately, introducing source location into the policy design complicates matters; it is easier said than done.
From a purely theoretical point of view, the challenge is easily manageable. All the control authority has to do is to implement the ambient permit system described in chapter 2. Unfortunately, the implementation of this system would not be a trivial matter. Both state control authorities and sources would have to overcome some rather formidable administrative and legislative barriers if an ambient permit system is to work smoothly in practice.____________________