U.S. Environmental Protection Agency

                        May 3, 1999
                                
      Document Re-Released for Stakeholder Review and Comment
                                
 Determination of Start Emissions as a Function of Mileage and
     Soak Time for 1981-1993 Model Year Light-Duty Vehicles
                            
                 Report Number EPA420-P-99-015

The Office of Mobile Sources, Assessment and Modeling Division,
announces the re-release of "Determination of Start Emissions as
a Function of Mileage and Soak Time for 1981-1993 Model Year
Light-Duty Vehicles" for stakeholder review and comment. This
document, also known as M6.STE.003, is available at the MOBILE6
section of the OMS Web Site (http://www.epa.gov/oms/m6.htm).

It is one of four documents (M6.STE.002, M6.STE.003, M6.EXH.001,
and M6.EXH.002) that collectively describe the methodology and
proposed findings on the in-use exhaust deterioration of
1981-1993 model year cars and trucks. All four documents are
being released concurrently for review. This document is being
re-released since it is related to the other three and has
undergone significant revision since the last posting.

MOBILE6 will allocate vehicle exhaust emissions to either those
associated with engine start (start emissions) or those
associated with travel (running emissions). This document
describes the methodology used to estimate start emissions as a
function of mileage and soak time for Tier 0 (i.e., 1981-1993
model year) light-duty cars and trucks, and presents the
estimates proposed for use in MOBILE6.

Comments on this report and its proposed use in MOBILE6 should be
sent to the attention of Ed Glover. Comments may be submitted
electronically to mobile@epa.gov, by fax to (734)214-4939, or by
mail to MOBILE6 Review Comments, US EPA Assessment and Modeling
Division, 2000 Traverwood Drive, Ann Arbor MI  48105. Electronic
submission of comments is preferred. In your comments, please
note clearly the document that you are commenting on including
the report title and the code number listed. Please be sure to
include your name, address, affiliation, and any other pertinent
information.

This document is being released and posted on May 3, 1999.
Comments will be accepted for sixty (60) days. EPA will then
review and consider all comments received, and will provide a
summary of those comments and how we are responding to them in
the form of a followup document.

Thank you for your continuing interest in the development of
MOBILE6.

                           Sincerely,
                                
   Emission Inventory Group, Assessment and Modeling Division
                US EPA Office of Mobile Sources