U.S. Environmental Protection Agency


       Document Released for Stakeholder Review and Comment

          Estimating Running Loss Evaporative Emissions
                     Based on Real-time Data 

                  Report Number   EPA420-P-99-024
                           M6.EVP.008

     In earlier versions of EPA's MOBILE model, running loss
emissions (defined as evaporative hydrocarbons that are emitted
when the vehicle is in operation) were calculated as functions of
ambient temperature, fuel volatility, driving cycle, and vehicle
parameters (i.e., fuel delivery system, model year ranges, and
functionality of the evaporative control system).  This report is
not a complete re-analysis of the older data used in those
previous versions of MOBILE.  Rather, this report examines the
effects of "gross liquid leakers" (see report M6.EVP.009), and
then compares recent running loss test results with the result of
combining the estimated emissions of those leaking vehicles with
the MOBILE5 running loss estimates.

     Please note that EPA is seeking any input from stakeholders
and reviewers that might aid us in modeling any aspect of running
loss evaporative emissions.

     Comments on this report and its proposed use in MOBILE6
should be sent to the attention of Larry Landman.  Comments may
be submitted electronically to mobile@epa.gov, or 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 July 14, 1999. 
Comments will be accepted for sixty (60) days, ending September
9, 1999.  EPA will then review and consider all comments
received and will provide a summary of those comments, and how we
are responding to them.