U.S. Environmental Protection Agency
Office of Transportation and Air Quality

November 2001

Document Released for Public Information

"Determination of NOx and HC Basic Emission Rates, OBD and I/M
 Effects for Tier 1 and Later LDVs and LDTs"

Final Report     EPA420-R-01-056      (M6.EXH.007)

Authors: John Koupal and Edward Glover


ABSTRACT

     The Office of Transportation and Air Quality, Assessment and
Standards Division announces the release of "Determination of NOx
and HC Basic Emission Rates, OBD and I/M Effects for Tier 1 and
Later LDVs and LDTs" for public information.  This document
EPA420-R-01-056, also known as M6.EXH.007, 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 develop NOx
and HC basic emission rates, OBD (On-board Diagnostics II)
effects, and I/M (Inspection / Maintenance) credits for Tier 1
vehicles, TLEVs (Transitional Low Emitting Vehicles), LEVs (Low
Emitting Vehicles), and ULEVs (Ultra Low Emitting Vehicles). This
document also describes the modeling for several program types
(i.e., with and without OBD checks, with and without exhaust I/M
testing) and combinations of these types. The methodology for CO
emissions is described in a separate document (M6.EXH.009).

     This final version supercedes the draft version published in
May 1999. It addresses comments from external peer review, and
comments received during the proposal phase of the Tier 2
rulemaking.