cause costs are such an important element for understanding the impacts of state emissions standards, the committee finds a need for a comprehensive study of the costs of state standards. This study should include the difference in costs for the states that adopt California standards compared with costs for California, the distribution of those costs, and their cost-effectiveness. Costs should be viewed broadly and include the costs to manufacturers and distributors to develop and distribute products certified under two emissions standards and the costs to states to implement, enforce, and maintain the program.


Recognizing the needs of some states to adopt more stringent mobile-source emissions standards to help meet air quality goals, a desirable objective is harmonization of CARB’s and EPA’s certification procedures. Although harmonization is a worthy pursuit when the interests of the federal government and the states coincide, there are areas where their priorities diverge (Chapters 5 and 6).


Regulators should make a determined effort to harmonize the procedures for testing and certification and look for opportunities to harmonize the emissions standards. Domestically, CARB and EPA should conduct a biennial assessment, either through a written report or public meeting, of where emissions testing and certification procedures can be harmonized and what emissions standards can be harmonized. The committee recognizes that EPA is leading the U.S. participation in international efforts to harmonize emissions standards and testing procedures. EPA should continue these efforts and encourage international participation in the biennial harmonization assessments. The committee recognizes that many countries will lag in the adoption of mobile-source emissions standards; therefore, global efforts to harmonize may need to focus initially on emissions testing and certification procedures.

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