Current marine air emissions policy on a national level is administered through
the EPA’s Office of Transportation and Air Quality. The EPA has taken the lead
nationally in marine air emissions standards, requiring engines to adhere to both U.S. and
MARPOL standards. MARAD (Department of Transportation Marine Division) is an
active participant in several working groups and forums intended to find ways to bring
U.S. shipping into compliance with EPA rules.


Tier II of the U.S. EPA regulations defining emissions limits for all U.S. marine
diesel engines will go into effect at the beginning of 2007. 

Emissions from C2 marine engines are not to exceed 11 g NOx/kw-hr and 0.5 g PM/kw-hr, starting in 2007. 

Older engines will be “grandfathered” under these regulations, and will not be held to the
standards. Engine manufacturers can also forgo regulations for individual engines if they
enter into a "trading" program, which averages emissions to families of engines. The
averages are substantially less stringent (1.2 for PM and 14.6 for NOx). 


In addition, the EPA has mandated a reduction of sulfur in marine diesel fuel to 500 ppm by 2007 and to
15 ppm by 2010. 

As well, more restrictive (Tier III) emission limits for C2 marine diesel
engines will go into effect in 2011.