January 27, 1998
                                
      Document Released for Stakeholder Review and Comment
                                
         "Air Conditioning Activity Effects in MOBILE6"
                    Report Number M6.ACE.001

The Office of Mobile Sources, Assessment and Modeling Division,
announces the release of "Air Conditioning Activity Effects in
MOBILE6" for stakeholder review and comment.  This document
(M6ACE001.PDF) is available at the MOBILE6 section of the OMS Web Site
(http://www.epa.gov/omswww/models.htm).

ABSTRACT:

MOBILE6 will include revised estimates of exhaust emissions resulting
from air conditioning operation.  This will require air conditioning
behavior and the resultant emission levels to be predicted over a wide
range of ambient conditions.  Test data used to develop these factors
were gathered under conditions meant to represent a single extreme set
of conditions.  This report addresses EPA's proposed methodology for
applying the "extreme" data over the broader range of ambient
conditions in which air conditioner operation occurs in-use.  Using
air conditioning activity data collected in Phoenix, a methodology has
been developed which relates temperature and humidity levels to air
conditioner load using a combined measure known as the heat index.
This methodology also incorporates some solar load impact and will
allow adjustments for cloud cover if desired by the user.  Estimates
have also been developed for the fraction of vehicles equipped with
air conditioning systems, and of those, the fraction of malfunctioning
systems. 

Comments on this report and its proposed use in MOBILE6 should be sent
to the attention of John Koupal.  Comments may be submitted
electronically to mobile@epamail.epa.gov, or by fax to (313)741-7939,
or by mail to MOBILE6 Review Comments, US EPA Assessment and Modeling
Division, 2565 Plymouth Road, 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 January 27th.  Comments
will be accepted for sixty (60) days, ending March 28th.  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 within 30 days after the close of the
comment period (April 27).

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