The design and implementation of vehicle scrapping programs

A number of metropolitan air basins in the US are currently faced with increased difficulty in attaining national and regional clean air standards. Significant controls on stationary sources over the years have allowed mobile sources to become the primary source of air emission in many areas. Programs allowing the use of mobile source offsets for stationary source emission by removal of older, higher emitting vehicles through scrappage programs are, therefore, conceptually attractive and are starting to be implemented. However, achieving success in such scrappage programs is a challenge given the associated technical, economic and social issues. This paper presents a discussion of the important issues that must be considered if vehicle scrappage programs are to be successful, including recent guidance and views of the EPA and state governments on the credits associated with the programs. Although the main focus of such programs is the reduction of criteria pollutants (CO, ROG, NOx, and PM10), the impact on air toxics also has to be considered. The paper will then focus on the technical design of vehicle scrappage programs such that the resulting credits are real, verifiable, enforceable, and cost-effective. Information available under existing vehicle I/M programs along with economic, vehicle maintenance, and geographic data will be used with statistical techniques in order to meet predetermined program goals regarding emissions reduction and cost-effectiveness. A later case-study paper will discuss the actual implementation of such as program in an ozone non-attainment area