Timing and Scope of Emission Reductions for Airborn Particulate Matter: A Simplified Model

Environmental health policy decisions are characterized by irreversibility and uncertainty of an economic, ecological and biomedical nature. For this reason decision-makers may choose to exercise when possible some discretion over the timing and scope of policy. Problems of this kind fall within the framework of the theory of irreversible investments as applied to the sunk costs and sunk bene ts of environmental regulation. This work is an application of the basic theory to the problem of timing and scope of emissions reductions for airborne particulate matter. Particular attention is given to the representation of health e ects in a simpli ed model of bene t-cost uncertainty. The results describe analytically and illustrate numerically a decision rule for optimal policy. The exposition is designed primarily for the bene t of quantitative policy analysts in the areas of environmental and health regulation.