OVERVIEW OF PROBLEMS TO BE RESOLVED WHEN MEETING THE 1991 BUS PARTICULATE EMISSIONS STANDARD

An overview of the engine-fuel-technology-transition problems that may be created for transit systems if the strict 1991 bus particulate and nitrogen oxides emissions standards remain in force is presented. The estimates of costs and benefits of the two standards combined are called into question. The problems created for manufacturers by the particulates--nitrogen oxides trade-off and the tight technology development schedule are reviewed. By introducing the perspective that emissions from transit buses should be thought of in terms of emissions per passenger mile, the 1991 treatment of buses with respect to nitrogen oxides emissions is called into question. The unique spatial relationships among buses, downtown pedestrians, and metropolitan places of residence are taken into account when evaluating the differing effects of nitrogen oxides and particulates bus emissions. Based on this examination, the strict 1991 particulate emission standards are accepted as desirable, but it is asserted that very little reason has been demonstrated to support hte strict 1991 nitrogen oxides standards for buses.