Why do mobile source NOx emissions jump higher between 2001 and 2002 on the emissions trends?

The emissions model used for mobile sources changed from MOBILE6.2 to MOVES 2010 in December 2009.  This change included a notable increase in NOx emissions.  The EPA adjusted data back to 2002 to reflect the change in models.  The higher emissions in 2002 are because of this method change and not because of real increases in NOx emissions from mobile sources.  Additional information about the differences between MOVES and MOBILE6.2 is available on the EPA Website “Previous MOVES Versions and Documents.”