INTRODUCTION TO DIESEL PARTICULATE EMISSIONS, ALTERNATIVE FUELS, AND THE TRANSIT INDUSTRY

The papers presented in this Record are on various aspects of the diesel fuel emissions control problem now facing the public transit industry as a result of new Environmental Protection Agency emissions standards for heavy-duty engines (40 C.F.R. Part 86). From 1991 to 1994, these standards place lower particulate emissions requirements on buses than on trucks. There is considerable doubt that the traditional two-stroke diesel bus engine can, while continuing to use diesel fuel, be modified sufficiently to meet the requirements set by the standards. However, because this type of engine can meet the 1991 requirements when using methanol fuel, the issue of alternate fuels is inextricably intertwined with that of emissions compliance for buses. Further, although it is expected that four-stroke diesel engines will eventually be able to meet the standard, they are not likely to do so when the 1991 particulate standard takes effect for buses. There are many issues related to and points of view on this controversial topic. This introduction highlights the major technical, health, and regulatory factors involved. The authors of the papers assume background familiarity with the overall issue and focus on particular aspects of their work. This introduction is intended to help to place all of the papers in context for those readers who are new to this topic.