U.S. Environmental Protection Agency

April 2001

Document Released for Public Information

"Estimating Running Loss Evaporative Emissions in MOBILE6"

Report Number   EPA420-R-01-023     (M6.EVP.008)
 
	The Office of Transportation and Air Quality, Assessment and 
Standards Division announces the release of "Estimating Running Loss 
Evaporative Emissions in MOBILE6" for public information.  This 
document EPA420-R-01-023, also known as M6.EVP.008, is available at 
the MOBILE6 section of the OTAQ Web Site 
(http://www.epa.gov/otaq/m6.htm).

	This report documents the method used in MOBILE6 for 
estimating the running loss emissions from vehicles.  

	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 incorporates the effects of "gross 
liquid leakers" (see report M6.EVP.009) with the MOBILE5 running loss 
estimates, and then verifies that this approach is consistent with the 
results of recent running loss testing (while the MOBILE5 estimates 
alone are not).

	This report was originally released (as a draft) in June 1999.  
This current version is the final revision of that draft.  This final 
revision incorporates suggestions and comments received from 
stakeholders during the 60-day review period and from peer reviewers.