Air Pollution from Ships: MARPOL Annex VI and Other Control Options
Air Pollution from Ships:
MARPOL Annex VI and Other Control Options
Updated September 9, 2008
James E. McCarthy
Specialist in Environmental Policy
Resources, Science, and Industry Division
Air Pollution from Ships:
MARPOL Annex VI and Other Control Options
This report provides information regarding pollution from ships and port
facilities; discusses some of the measures being implemented and considered by
local, state, and federal regulatory agencies; discusses the efforts to ratify and to
strengthen Annex VI of the International Convention for the Prevention of Pollution
from Ships (MARPOL); and describes legislation Congress is considering to control
emissions from ships by amending the Clean Air Act (CAA).
As pollution from cars, trucks, and land-based stationary sources has been more
tightly controlled over the last 40 years, the contribution of ships and port operations
to air pollution in port cities has become more important. In the same period, foreign
trade has grown dramatically; thus, pollution from shipping and port operations
would be growing as a percentage of total emissions, even if the emissions were
regulated to the same degree as other sectors. In many cities, ships are now among
the largest sources of air pollution.
Controlling these sources is complicated by the fact that most ocean-going ships
are not registered in the United States and may not even purchase the fuel they are
using here. Thus, controlling such pollution would seem to lend itself to an
international approach. To date, such efforts have been of little avail. In 1997, the
United States and most countries signed an international agreement known as
MARPOL Annex VI, setting extremely modest controls on air pollution from ships.
The agreement did not enter into force until 2005, and the United States took until
July 21, 2008, to enact legislation to implement it (H.R. 802, P.L. 110-280).
While awaiting congressional action, the Environmental Protection Agency
(EPA), port cities, and states began to act on their own, and, in Congress, other
legislation has been introduced (S. 1499 / H.R. 2548) to require EPA to dramatically
strengthen ship emission standards under the Clean Air Act.
Negotiations to strengthen MARPOL Annex VI are also under way. The parties
are expected to vote at the next negotiating session (October 6-10, 2008) to approve
provisions that would strengthen Annex VI.
In troduction ......................................................1
MARPOL Annex VI...............................................3
Provisions of Annex VI.........................................3
Implementing Legislation (H.R. 802)..............................4
Federal, State, and Local Measures....................................5
Category 3 Engines........................................6
Category 1 and 2 Engines...................................6
California Emission Reduction Measures...........................7
Low Sulfur Fuels..........................................7
Air Pollution from Ships: MARPOL Annex VI
and Other Control Options
Over the last 40 years, air quality in the United States has improved
substantially. Since the passage of the Clean Air Act in 1970, annual emissions of
the six most widespread (“criteria”) air pollutants have declined 160 million tons
(53%), despite major increases in population, motor vehicle miles traveled, and1
Emissions from shipping are a major exception to these trends. Although
emission controls have reduced pollution from new cars and trucks by more than
90%, most ocean-going ships operate without any pollution controls at all. New and
remanufactured engines on tug boats, ferries, and other smaller ships will be subject
to emission controls beginning in 2008 and 2009, but most existing engines in
vessels of these types remain uncontrolled.
Pollution from ships is also affected by the fuel they use. Marine vessels other
than oceangoing ships have been required to use cleaner fuels, but ocean-going ships
generally use bunker fuel, a fuel that contains a high level of contaminants: the
average fuel used by oceangoing ships contains 27,000 parts per million (ppm) sulfur,
for example — almost 2,000 times as much as would be allowed in trucks operating
on U.S. roads.
In the Los Angeles-Long Beach area — which is both the nation’s busiest port2
and the nation’s most polluted area3 — the problem is particularly acute. According
to the South Coast [L.A.-Long Beach] Air Quality Management District (AQMD):
1 See U.S. EPA, “Air Emissions Summary Through 2005,” at [http://www.epa.gov/air/
airtrends/2006/emissions_summary_2005.html]. The six criteria pollutants are ozone,
particulate matter, carbon monoxide, sulfur dioxide, nitrogen oxides, and lead.
2 According to the Wall Street Journal, Los Angeles and Long Beach ranked number 1 and
number 2 in the value of cargo handled, with a combined total exceeding $248.5 billion in
2003-2004. The port of New York and New Jersey ranked third with $132.4 billion. See
“The Busiest U.S. Ports,” March 9, 2006, at [http://americanfuture.net/?p=1447].
3 The Los Angeles South Coast Air Basin is the only area that EPA considers to be a
“Severe” nonattainment area for ozone. The area also has the highest readings in the
country for fine particulates (PM2.5), and is among only 8 areas classified as “Serious”
nonattainment areas for larger particles (PM10). See U.S. EPA, “Green Book,” at
[ ht t p: / / www.epa.gov/ oar / oaqps/ gr eenbk/ i ndex.ht ml ] .
!Oceangoing vessels are among the largest sources of nitrogen oxides
(NOx) in the area, emitting more NOx than all power plants and
refineries in the South Coast air basin combined. NOx reacts with
volatile organic compounds in the atmosphere to produce
!70% of the area’s emissions of sulfur dioxide (SO2) come from
ships. These emissions need to be cut by over 90%, according to the
AQMD, if the area is to attain the national air quality standard for
particulates by the 2014 deadline.
!Particulates from marine vessels also create significant cancer risks.
!More than 700 premature deaths are caused in the Los Angeles area
annually by these emissions, according to the AQMD.4
While the Los Angeles-Long Beach area may be the most extreme example, the
problem is not limited to L.A. or even to California. According to the Environmental
Protection Agency (EPA), more than 40 U.S. ports nationwide are located in
“nonattainment” areas5 for ozone, fine particulates, or both.6 In addition, according
to EPA, “... the problem is not limited to port areas alone. Santa Barbara County,
which has no commercial ports, estimates that by 2020, 67 percent of its NOx
inventory will come from shipping traffic transiting the California coast....”7
Oceangoing ships are perhaps the largest source of port emissions, but they are
not the only source. Ports make use of tug boats to guide ships entering and leaving
the harbor. Ports make connections to land-based transportation networks, such as
railroads, and they generally operate large truck terminals. Ships at rest in the port
need a source of power, which often comes from running auxiliary engines. And, in
many cases, a harbor is served by substantial local boat or barge traffic, sometimes
including ferry service. Thus, addressing the sources of pollution in a port may
require a multi-faceted approach.
4 See testimony of Barry R. Wallerstein, Executive Officer, South Coast Air Quality
Management District, at “Legislative Hearing on the Marine Vessel Emissions Reduction
Act of 2007, S. 1499,” U.S. Senate, Committee on Environment and Public Works, February
5 That is, areas where air quality is worse than the health-based standard for ozone,
particulates, or both.
6 Testimony of Bryan Wood-Thomas, U.S. EPA, Office of Transportation and Air Quality,
at “Legislative Hearing on the Marine Vessel Emissions Reduction Act of 2007, S. 1499,”
U.S. Senate, Committee on Environment and Public Works, February 14, 2008, p. 2.
MARPOL Annex VI
Pollution from ships (not only air pollution, but pollution of all kinds) is
governed by the International Convention for the Prevention of Pollution from Ships,
first negotiated through the International Maritime Organization (IMO) in 1973. The
Convention, known as MARPOL (for “MARine” “POLlution”) 73/78 (the dates
referring to the 1973 Convention and its 1978 amendments), applies to all ships of
the flag states that have ratified it. About 150 countries, representing over 98.7% of
world shipping tonnage, have done so. The Convention also applies to ships of non-
signatory states while they are operating in waters under the jurisdiction of parties to
MARPOL. Six annexes to MARPOL 73/78 cover various sources of pollution from
ships (oil, noxious liquids, sewage, garbage, etc.) and provide an overarching
framework for implementation.
Provisions of Annex VI
Annex VI of the Convention, which was adopted in 1997 but did not enter into
force until 2005, addresses the Prevention of Air Pollution from Ships. The annex
represents a small first step toward controlling such pollution, particularly if one
compares it to pollution controls that the United States and other developed countries
impose on land-based sources. Annex VI:
!limits the sulfur content of the fuel used in oceangoing ships (bunker
fuel) to 4.5% (45,000 parts per million (ppm)). By comparison,
highway diesel fuel in the United States is limited to 15 ppm;
!allows special sulfur oxide (SOx) Emission Control Areas (currently
the Baltic Sea, the North Sea, and the English Channel), where the
sulfur content of fuel is limited to 1.5% (15,000 ppm) or SOx
emissions are limited;
!limits NOx emissions from new engines and engines that have
undergone major conversions to a range of 9.8-17.0 grams per
kilowatt-hour (g/kwh). By comparison, power plants in the eastern
United States are limited to 0.45-0.73 g/kwh;
!allows the regulation of emissions of volatile organic compounds
(VOCs) from tankers by parties to Annex VI in their ports and
!prohibits emissions of ozone-depleting substances;
!prohibits the incineration on ships of polychlorinated biphenyls
(PCBs, a class of toxic chemicals widely used in electrical
transformers until the 1970s). In the United States, PCB production
and use were banned in 1976, and disposal has been strictly
regulated since then; and
!prohibits the incineration of garbage containing more than traces of
heavy metals and of refined petroleum products containing halogen
Implementing Legislation (H.R. 802)
The United States is a party to MARPOL 73/78 and most of its annexes, but did
not enact legislation to implement Annex VI until the summer of 2008. The Senate
gave its consent to ratification of Annex VI on April 7, 2006,9 but Congress needed
to enact implementing legislation before the United States could submit the
instrument of ratification. The House passed H.R. 802 to implement the annex on
March 26, 2007. The Senate passed the bill, with an amendment, June 26, 2008, and
the House agreed to the Senate amendment July 8. The President signed the bill July
The United States has participated in negotiations to strengthen Annex VI.
More stringent limits on both fuels and emissions were approved by an IMO
committee April 4, 2008 and will be considered for final adoption at the next meeting
October 6-10, 2008. The United States supports the strengthening amendments,
although it will not be able to vote at the meeting because of the delay in enacting
legislation to implement Annex VI. EPA believes that the strengthening amendments
will be adopted by unanimous consent of the parties. Thus, the inability of the
United States to vote may not be of much significance.
EPA has already promulgated regulations under the Clean Air Act that are as
stringent as Annex VI, and shipping companies are already generally meeting the
standards. These so-called “Tier 1” standards were promulgated February 28, 2003,
and went into effect in 2004.10 In addition, in October 1999, EPA established a
voluntary certification program so that engine manufacturers could show that their
engines are compliant with Annex VI. EPA believes that all marine diesel engines
sold in the U.S. since January 1, 2000, to which the annex applies (i.e., those rated
above 130 kilowatts), meet Annex VI requirements.
The Annex VI standards apply to: any oceangoing vessel that is registered in the
United States; ships of any registry in ports, shipyards, terminals, or the internal
waters of the United States; ships of any registry bound for or departing from the
United States, while they are located in the navigable waters of the United States or
designated emission control areas; and ships bearing the flag of any country that has
ratified Annex VI traveling through U.S. waters or designated emission control areas,
even if they are not bound for or departing from a U.S. destination. To the extent
consistent with international law, the Annex also applies to any other ship in the U.S.
exclusive economic zone.
8 For a more detailed description of Annex VI provisions, see Det Norske Veritas, MARPOL
73/78 Annex VI, Regulations for the Prevention of Air Pollution from Ships, Technical and
Operational Implications, 21 February 2005 at [http://exchange.dnv.com/Documentation/
DNV Exchange /Fleet/DNV _paper_Marpol_Annex_V I.pdf].
9 The Senate consented to ratification through Treaty Document 108-7.
10 68 Federal Register 9746, February 28, 2003.
In addition to the bill to implement Annex VI, other legislation on ship
emissions has seen committee action in the Senate. S. 1499, reported by the
Environment and Public Works Committee, July 10, 2008 (S.Rept. 110-413), would
amend the Clean Air Act to require oceangoing vessels entering or leaving U.S. ports
and offshore terminals to use fuel that contains no more than 1,000 parts per million
of sulfur (a 98% reduction from the requirement of Annex VI) beginning on
December 31, 2010. The restrictions would apply within 200 miles of the West
Coast and within such distance of the East or Gulf coast or the shoreline of the Great
Lakes or St. Lawrence Seaway as EPA determines to be appropriate.11 The
Administrator would be allowed to provide an alternative mechanism of compliance
if he determined that a vessel employed a control technology that reduced emissions
of sulfur oxides and particulate matter to at least the same degree as the reduction
that would be achieved through compliance with the sulfur content limitation.
In addition to the fuel standards, the bill would require EPA to promulgate
emission control standards for main and auxiliary engines on oceangoing vessels that
enter or leave U.S. ports. The standards would require the greatest achievable
emission reduction for four pollutants (nitrogen oxides, particulate matter,
hydrocarbons, and carbon monoxide) effective January 1, 2012. The standards could
take into account the feasibility, benefits, and costs of specific technologies; could
distinguish new from in-use engines; and could vary depending on the age of the
A similar bill, H.R. 2548, was introduced by Representative Solis in the House,
but no action has been taken there.
Federal, State, and Local Measures
Beyond Annex VI and the pending Senate and House bills, potentially more
stringent actions are being taken at the federal, state, and local level to address
emissions from marine engines.
EPA has begun to regulate ship emissions under existing Clean Air Act
authority. Thus far, the regulations are relatively weak, and it will be at least 2014
before the agency’s regulations impose stringent requirements in most cases. Also,
when the more stringent requirements do take effect, they will apply only to new and
remanufactured engines, so improvements resulting from the standards will be
11 The Administrator may promulgate regulations that permit sulfur content as high as 2,000
ppm for a specified period if he determines that compliance with the 1,000 ppm limit is not
technically feasible by December 31, 2010.
Category 3 Engines. EPA categorizes ship engines in three categories. The
largest of these engines — the main engines on oceangoing ships — are diesel
engines with a per-cylinder displacement at or above 30 liters. These are referred to
as “Category 3” engines. As noted, the agency has already promulgated regulations
equivalent to Annex VI for these engines under the Clean Air Act. But, as the agency
states on its website, “There is an opportunity to gain large additional public-health
benefits from Category 3 marine diesel engines through the application of advanced
technology emission controls including high-efficiency catalytic aftertreatment.”12
The agency has begun the process of developing more stringent regulations, by
issuing an Advance Notice of Proposed Rulemaking December 7, 2007. It plans to
finalize new Category 3 regulations by December 17, 2009.
Whether or not the agency promulgates more stringent Category 3 emission
standards, they may have little effect on the overall level of pollution from Category
3 ships, since they will only apply to engines installed on vessels flagged or
registered in the United States. In 2007, only 6.7% of the world’s ships (and only13
Category 1 and 2 Engines. By contrast, the Category 1 and 2 engines
(those smaller than 7 liters per cylinder, and those from 7 to 30 liters per cylinder,
respectively), are used in boats or ships that operate in U.S. waters — tugs, ferries,
Great Lakes freighters, fishing boats, and recreational boats, for example — virtually
all of which are registered in the United States. And, compared to Category 3, EPA
is further along in regulating the emissions of these categories. Regulations that will
reduce emissions of NOx from new or remanufactured engines by 24% and
emissions of particulates by 12% when fully implemented, were promulgated in 1999
and began taking effect between 2004 and 2007. More stringent standards were
promulgated May 6, 2008, and will take effect between now and 2014.14 The final
2014 standards will require ultra low sulfur diesel fuel (15 ppm sulfur) and high
efficiency catalytic emission controls capable of reducing particulate matter
emissions by 90% and NOx emissions by 80%, along with “sizeable reductions” of
hydrocarbon, carbon monoxide, and air toxic emissions, according to EPA.15
EPA has also proposed new Annex VI standards, covering both fuel and
engines, at international negotiations under the auspices of IMO. As noted earlier,
the more stringent limits were approved by an IMO committee April 4, 2008 and will
be considered for final adoption at a meeting October 6-10, 2008.16
12 U.S. EPA, Office of Transportation and Air Quality, “Oceangoing Vessels,” at
[ h t t p : / / www.e p a . go v/ ot a q / o c e a n ve s s e l s .ht m] .
13 United Nations Conference on Trade and Development, Review of Maritime Transport
14 73 Federal Register 25097, May 6, 2008.
15 For information, see U.S. EPA, Office of Transportation and Air Quality, “Diesel Boats
and Ships,” at [http://www.epa.gov/oms/marine.htm].
16 See “International Committee Approves Changes to Rules on Sulfur Content in Ship
Fuels,” Daily Environment Report, April 8, 2008, p. A-5. In addition to approving limits on
California Emission Reduction Measures
California, being more adversely affected than most other areas, has played a
leadership role in identifying and implementing emission reduction measures, as
well. The state has focused on port activities, in addition to fuel and emission
standards. California’s measures fall into four categories: 1) requiring the use of
lower sulfur fuel; 2) requiring emission controls on harbor vessels and shore-side
equipment; 3) providing alternative (electric) power to ships while they are docked
at marine terminals ; and 4) providing grants for the re-powering of harbor craft and
short-haul trucks with cleaner engines.
Low Sulfur Fuels. The California Air Resources Board (CARB), at a July
flagged vessels sailing within 24 miles of its coast to use low sulfur fuels in both
main and auxiliary engines beginning July 1, 2009. Compliant fuels are marine
diesel oil with 5,000 ppm or less sulfur or marine gas oil with 15,000 ppm or less
sulfur. In January 2012, sulfur in both types of fuel would be limited to 1,000 ppm.
The rules replace low sulfur fuel requirements that the state implemented in 2007, but
which were overturned by the U.S. Court of Appeals for the Ninth Circuit earlier this17
year. The original rules would have set a 1,000 ppm limit two years earlier, in
Emission Controls. California has, in general, led the nation in imposing
more stringent requirements on diesel engines. In addition, the ports of Los Angeles
and Long Beach have developed procedures to require that trucks serving the ports
will be replaced by newer, less-emitting models. According to a description of the
... all pre-1989 trucks will be barred from entering the ports’ terminals beginning
Oct. 1 . Effective Jan. 1, 2010, all 1989-1993 trucks and any 1994-2003
trucks without certified pollution control equipment will be banned. By Jan. 1,
2012, all trucks entering the port must meet the 2007 federal standard for
heavy-duty diesel trucks....
sulfur content of fuel, the committee approved somewhat more stringent limits on NOx
emissions. According to the article, “The proposed amendments will now be circulated
among IMO members for comment before final adoption at the next Marine Environment
Protection Committee meeting in October, according to a spokeswoman. It is ‘extremely
unlikely’ any changes will be made at this point, the IMO spokeswoman added.”
17 Pacific Merchant Marine Ass’n v. Goldstene, 517 F.3d 1108 (9th Cir. 2008). The court
held that the state’s Marine Vessel Rules were preempted by the federal Clean Air Act
because the regulations set emission standards for marine engines without California having
received a waiver from EPA to do so. California has since asked EPA for a waiver to
enforce the original rules, in addition to developing the rules applying only to fuels. See
“California Air Board Seeks Federal Waiver to Enforce Ship Auxiliary Engine Rules,” Daily
Environment Report, May 13, 2008, p. A-1.
A $35 gate fee for each 20-foot container unit that passes through the port will18
generate funds to help underwrite subsidies to upgrade and replace trucks.
In addition, CARB has adopted regulations for harbor craft, including ferries,
tugboats, and tow boats, which will require the replacement of unregulated engines
beginning in 2009, and will accelerate the adoption of EPA’s Category 1 and
Category 2 marine engine pollution controls. These rules are still undergoing public19
comment prior to final approval.
Alternative Power. In June 2004, the Port of Los Angeles opened the world’s
first Alternative Maritime Power (AMP) terminal for container ships, where cargo
ships can plug in to power instead of operating auxiliary engines to generate
electricity while at berth. The electrification project was the result of a lawsuit
brought by the Natural Resources Defense Council and other groups, who sued the
city claiming it failed to fully weigh air quality and other environmental impacts of
the new container terminal. As a result of the suit, a state appeals court halted work
on the terminal in October 2002, and Los Angeles subsequently agreed to electrify20
the terminal to cut diesel emissions while ships are at docks, among other measures.
A second terminal was outfitted with AMP capability in 2005. To encourage
shippers to use the AMP facilities, in December 2004, the Los Angeles Board of
Harbor Commissioners passed a policy resolution to help each existing Port customer
underwrite the cost of building or retrofitting their first container or cruise ship to run
on electrical power when docked, a cost estimated at $320,000 - $830,000 per21
vessel. Cruise ship terminals in San Francisco and Seattle are also implementing
AMP, and CARB is in the process of drafting regulations to require the use of AMP22
at six of the state’s ports.
Grants. CARB, the Port of Los Angeles, and the South Coast Air Quality
Management District are also providing substantial amounts of financial support for
the replacement of older, high-emitting engines and the conversion to lower emitting
power sources. CARB will award $221 million in FY2007-08 funds for “goods
movement emission reduction” projects, and the Governor has requested a second
installment of $250 million in FY2008-09. Most requests for the funds have come
from trucking companies, which would replace older engines or trucks with new
18 “Los Angeles Harbor Commission Approves Program to Replace Older Diesel Trucks,”
Daily Environment Report, March 24, 2008, p. A-9.
19 Information on these regulations can be found at [http://www.arb.ca.gov/regact/2007/
20 Natural Resources Defense Council v. City of Los Angeles, 126 Cal. Rptr. 2d 615 (Cal.
21 See Port of Los Angeles, “Alternative Marine Power,” at [http://www.portoflosangeles.
org/environment/alt_maritime_power.asp]. Also see “Alternative Maritime Power “Off and
Running,” presented by Eric Caris, at [http://www.ffca2006.com/documents/presentations/
22 See California Air Resources Board, “Rulemaking to Consider Adoption of Proposed
Regulations to Reduce Emissions from Diesel Auxiliary Engines on Ocean-Going Vessels
While at Berth at a California Port,” December 6, 2007, at [http://www.arb.ca.gov/regact/
models that reduce emissions as much as 90%.23 In addition, as noted, the ports will
provide subsidies for truck and engine replacement from a fund generated by a $35
per container fee. The grants will cover up to 80% of new truck cost.
As pollution from cars, trucks, and land-based stationary sources has been more
tightly controlled over the last 40 years, the contribution of ships and port operations
to air pollution in port cities has become more important. Simultaneously, foreign
trade has grown dramatically, adding to the burden of pollution from these sources.
Thus, pollution from ships and the port operations that serve them is now among the
most important sources of sulfur oxides, nitrogen oxides, particulates, and other
pollutants in numerous U.S. cities.
Controlling these sources of pollution is complicated by the fact that most
oceangoing ships are registered in foreign countries. Thus, initial efforts at control
were focused on international negotiations through the IMO, which established a
basic structure (MARPOL Annex VI) that may be the basis of more stringent future
controls. Negotiating, ratifying, and implementing MARPOL agreements is time-
consuming, however, and thus far, has not resulted in more than token levels of
regulation. Thus, EPA and state and local agencies (particularly those in California)
have begun to address pollution from ships using the Clean Air Act and comparable
Not all pollution from marine vessels comes from foreign ships. Smaller craft,
such as ferries, tugboats, and fishing boats do tend to be registered in the United
States, and are thus more amenable to control. Even for these smaller craft, the
technical issues can be complex, as the vessels include a wide variety of engine sizes
and ship configurations. Safety also poses important considerations, as ships must
be able to depend on their sources of power in what may be extreme weather
conditions and while dealing with a variety of navigational hazards.
Because ships and port operations are now such significant sources of air
pollution, further regulatory and legislative efforts to control their emissions are
likely. In addition, ships are a large and growing source of greenhouse gas
emissions; how and whether to regulate these emissions are the subject of IMO
discussions and may enter into the larger debate over legislation to address climate
Congress has begun efforts to address these problems, and enacted legislation
to implement MARPOL Annex VI in July 2008. But this is likely to be just the start
of Congressional attention to air pollution from ships. Action at the state level, in the
courts, and at U.S. EPA will continue to bring the issue to Congress’s attention, with
numerous opportunities for oversight and legislation.
23 See CARB, “Emissions Reduction Plan for Ports and Goods Movement in California:
Update on Implementation,” Staff Presentation, Air Resources Board Meeting , Oakland,
CA, April 24, 2008 at [ftp://ftp.arb.ca.gov/carbis/board/books/2008/042408/08-4-7pres.pdf].