U.S. Environmental Protection Agency

February, 2002

Document Released for Public Information

"Development of Heavy-Duty NOx OFF-CYCLE Emission Effects for MOBILE6" 

Report Number   EPA420-R-02-004     (M6.HDE.003)
 
	The Office of Transportation and Air Quality, Assessment and 
Standards Division announces the release of "Development of Heavy-Duty NOx OFF-CYCLE 
Emission Effects for MOBILE6" for public information.  This document EPA420-R-02-004, 
also known as M6.HDE.003, is available at the MOBILE6 section of the OTAQ Web Site 
(http://www.epa.gov/otaq/m6.htm). 

	This document describes the methodology used to estimate excess NOX emissions produced
by heavy-duty diesel vehicles (HDDV) as the result of Off FTP Cycle operation.  Also presented 
in the document are emission estimates based on two programs designed to mitigate the 
effect of the off-cycle operation on fleet NOX emission levels.   These include the 
incorporation of more stringent HDDV standards earlier than originally required (pull ahead), 
and accelerated engine rebuild programs (rebuild) to get in-use engines into better compliance.  

	This report was originally released (as a draft) in October, 2000 under the 
title, "Development of Heavy-Duty NOx OFF-CYCLE Emission Effects for MOBILE6".  
It was subsequently revised in February, 2002, and the February, 2002 is now the final version.
This final revision incorporates suggestions and comments received from stakeholders 
during the 60-day review period and from peer reviewers.