Mail Out #MSCD-99-28
September 23, 1999

TO: All Interested Parties

Dear Sir/Madam:

The staff of the Air Resources Board (ARB) will be holding public workshops to discuss a proposed public transit bus fleet rule, and a regulation setting lower emission standards for urban buses. The emissions from diesel urban buses are important due to their impact on ozone, and due to their high emissions of particulates that have been identified as a toxic air contaminant.

The proposed fleet rule would be applicable to future bus purchases by public transit operators. Adoption of the rule would result in lower emissions of oxides of nitrogen (NOx) and particulate matter (PM) by full-sized transit buses. The fleet rule requirements would be in the form of both conventional standards and voluntary incentive standards.

The proposed emission standards for NOx and PM would be applicable to manufacturers of heavy heavy-duty engines in urban buses (over 33,000 lbs. GVW). This regulation would result in long-term zero and near-zero public transit bus emissions in California.

At the workshops we will discuss lower-emission engine standards, NOx and PM emission reductions, bus technology, transit fleets’ capital and operating costs, and funding. Based on the input received at the workshops, staff will develop a fleet rule and urban bus standards that will be recommended to our Board at a public hearing in January 2000.

Originally, the ARB was considering including school buses and school districts as part of this regulation. However, staff now believes that additional time will be needed to address several of the issues specific to school buses. These issues include highly restricted funding, smaller fleets, and a relatively lower ozone impact. Emissions from school buses are still of serious concern to the ARB, primarily due to the high emissions of toxic particulates and the exposure of susceptible children to these emissions. A proposal addressing school buses will be evaluated in early 2000.

Two workshops are planned and the information presented by the staff will be identical at both workshops. The workshops will be held at the following date, time, and locations:

Monday, October 18, 1999

Wednesday, October 20, 1999

9:30 a.m. to 3:00 p.m

10:00 a.m. to 3:00 p.m.

Air Resources Board

Air Resources Board

Board Room, 2020 L Street

Annex 4, 9530 Telstar Avenue

Sacramento, California

El Monte, California

Additional information about the staff proposal is attached (Word - 257K) or (Acrobat -59K). Proposed regulatory language for the proposed bus fleet rule and the urban bus standards will be available after October 11, 1999, on the ARB web site,

If you have any questions regarding this workshop, please contact Mr. Robert Nguyen at (916) 327-2939 or, or Ms. Roberta Hughan at (916) 324-7583 or, in the Special Projects Section, Mobile Source Control Division, Sacramento, California. Written comments may be sent to Mr. Nguyen at P.O. Box 2815, Sacramento, California 95812.



Robert H. Cross, Chief
Mobile Source Control Division

Attachments (Word - 257K) or (Acrobat -59K).


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