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Posted: July 25, 2008

New law sets stage for U.S. to ratify MARPOL treaty

Under a new law signed by President Bush July 21, U.S. government agencies are taking measures to implement an international treaty that would regulate emissions from diesel-powered ocean-going ships.

The enactment of the Maritime Pollution Prevention Act of 2008 this month brings into statute Annex VI of the International Convention on the Prevention of Pollution from Ships (MARPOL) and makes it possible for the U.S. to ratify the treaty, the U.S. Environmental Protection Agency reported.

Under MARPOL Annex VI, containerships, tankers, cruise ships and bulk carriers must limit nitrogen oxide (NOx) emissions from category three diesel engines. Annex VI also sets a cap on the sulfur content of the fuel used by the engines and includes a program for designating areas where more stringent fuel controls apply, such as near coastlines that have more severe air quality concerns, the EPA reported.

MARPOL Annex VI entered into force beginning in May of 2005, although ships have met most provisions since 2000, the EPA reported.

For the U.S. to ratify the treaty, the President will have to deliver a letter to the International Maritime Organization, after which the U.S. would become a party to the treaty in three months, the EPA reported.

Amendments to Annex VI were developed earlier this year and are expected to be formally adopted by the IMO in October, the Congressional Information Bureau reported.

In general, MARPOL does not prevent a country from setting standards for its ships. Annex VI specifically allows a country to set alternative standards that would apply to engines on ships that operate solely in waters under its jurisdiction. To meet its obligations under the Clean Air Act to set standards for these engines, the U.S. is exercising these MARPOL provisions, according to a bulletin on the EPA Web site at

Both programs include compliance requirements for engine manufacturers, as well as ship owners and operators, according to the EPA bulletin.