United States
Environmental Protection
Air and Radiation
May 1998
Office of Mobile Sources
<&EPA Regulatory
Advance Proposal for Emission
Standards for New Diesel Marine
The U.S. Environmental Protection Agency (EPA) is issuing an
Advance Notice of Proposed Rulemaking (ANPRM) for emissions from
new diesel marine engines at or above 37 kilowatts (50 horsepower).
Control of emissions from this currently unregulated source moves the
Agency one step further in the initiative to reduce the harmful health
effects of ozone and particulate matter from nonroad engine sources.
A National Emission Control Program
The results of a 1990 EPA study demonstrated the need for control of air
pollution in the nonroad engine and vehicle arena. EPA published this
finding in conjunction with the first rulemaking to set emission standards
for nonroad engines, which was completed in June 1994. In September
1997, the Agency issued a proposal for more stringent emission
standards for diesel engines used in most nonroad applications, including
marine engines below 37 kilowatts. EPA is now considering proposing a
national program to control emissions of oxides of nitrogen (NOx) and
particulate matter (PM) from larger diesel marine engines. The Agency is
publishing an Advance Notice of Proposed Rulemaking to encourage a
broader dialogue with the public regarding the emission standards under
consideration. These engines are used for propulsion and auxiliary power
on both commercial and recreational vessels in a variety of marine
Printed on Recycled Paper

This ANPRM supplements an earlier proposal for these engines initiated
as part of an overall control strategy for new gasoline spark-ignition (SI)
and diesel compression-ignition (CI) marine engines. This new program
contains three sets of standards. First, for those marine diesel engines that
are derived from or use land-based nonroad or highway engine
technologies, EPA is contemplating an emission control program for
diesel marine engines similar to the Tier 2 program proposed for nonroad
land-based engines. Second, for engines that are derived from or use
locomotive technologies, EPA is contemplating numerical emission
limits similar to those applicable to land-based locomotives (finalized
December 17, 1997) or those contained in Annex VI of the International
Convention for the Prevention of Pollution from Ships (MARPOL 73/
78). Third, for low-speed, high-horsepower engines used to propel ocean-
going vessels, EPA is contemplating numerical emission limits adopted
by the International Maritime
Organization (IMO). The
certification and compliance
provisions being considered
are also derived from the
program for land-based
nonroad diesel engines, but
will reflect relevant
differences in locomotive-size
and larger marine engines that
are used domestically.
Emission Reductions Expected
If the standards and other requirements are implemented as proposed, the
resulting emission reductions would translate into significant, long-term
improvements in air quality in many areas of the U.S., particularly in port
cities and coastal areas. Application of emission controls similar to the
proposed nonroad Tier 2 standards are expected to result in NOx and PM
reductions comparable to those expected from land-based engines, on a
per-engine basis. The MARPOL Annex VI emission limits were intended
to result in a 30 percent reduction of NOx emissions; actual emission
reductions will depend on the age and other characteristics of the national
fleet. Overall, the program would provide much-needed assistance to
states facing ozone and particulate air quality problems that are causing a

range of adverse health effects for their citizens, especially in terms of
respiratory impairment and related illnesses.
Protection Agency
Public Participation Opportunities
EPA desires full public participation in arriving at rulemaking decisions.
The Agency solicits comments from all interested parties. Wherever
applicable, full supporting data and detailed analysis should also be
submitted to allow EPA to make maximum use of the comments.
Commenters are especially encouraged to provide specific suggestions
for changes to any aspects of the proposal that they believe need to be
modified or improved.
EPA will accept comments on the ANPRM for 30 days after publication
in the Federal Register, expected in March 1998. There will also be an
opportunity for oral and written comment when EPA publishes the
Notice of Proposed Rulemaking later in the year. For instructions on
submitting written comments, please see the Federal Register notice. It
is available from the EPA Air and Radiation Docket by calling 202-260-
7548; please refer to Docket No. A-97-50. In addition, the ANPRM and
related documents are available electronically via the EPA Internet server
For More Information
Additional documents on marine engines are available electronically at
the Internet site given above, or by contacting:
U.S. Environmental Protection Agency
Office of Mobile Sources
2000 Traverwood
Ann Arbor, Michigan 48105