Critical Issues > Vessel Air Emissions

VESSEL AIR EMISSIONS

The international maritime community has long been active in the pursuit of reducing pollution emanating from the commercial oceangoing vessels plying the world’s maritime trade.  The International Maritime Organization, starting in 1973, initiated negotiations to limit all forms of pollution from member nation’s vessel fleets, resulting in the adoption of the International Convention for the Prevention of Pollution From Ships (MARPOL).  In 1992, negotiations concerning vessel air emissions began, with the United States playing a lead role in the drafting of what is commonly referred to as MARPOL Annex VI.  This treaty establishes limits on the release of sulfur and nitrogen oxide emissions as well as known ozone depleting substances from ship exhaust fumes.

The International Maritime Organization adopted the treaty in 1997 which set limits on sulfur dioxide and nitrogen oxide emissions and prohibited intentional releases of ozone deleting substances. However, for the Annex to have the full force of international law 15 member nations with at least 50 percent of the world maritime tonnage are required for the treaty to enter into force.  That requirement was achieved in 2004, and MARPOL Annex VI came into effect in May of 2005.  In early October of 2008, the United States formally ratified MARPOL Annex VI, becoming the 53rd state to adopt the treaty when the United States instrument of ratification was deposited with the International Maritime Organization. In March of 2010, the IMO adopted a United States and Canadian proposal to designate waters 200 nautical miles off the North American coastline as an Emission Control Area (ECA). All large ships operating within the ECA must use fuel with a lower sulfur content, resulting in a reduction in particulate and nitrogen oxide emissions.

In the United States, the Clean Air Act is the comprehensive Federal law that regulates air emissions from area, stationary, and mobile sources. The law authorizes the Environmental Protection Agency (EPA), the lead implementing agency, to establish National Ambient Air Quality Standards to protect public health and the environment. The agency has established National Ambient Air Quality Standards for six criteria air pollutants – carbon monoxide, lead, ozone (formed by photochemical reactions of volatile organic compounds and nitrogen dioxide), nitrogen dioxide, sulfur dioxide, and particulate matter. The maritime industry is subject to the Clean Air Act and the EPA’s regulation of vessel air emissions.

The EPA promulgated a final rule on emission standards for new marine diesel engines in 2002. The rule established a “Tier 1” emission standard for U.S.-flag vessels only. Those standards mirror the internationally negotiated standards for oxides from the International Maritime Organization’s MARPOL Annex VI, Prevention of Air Pollution from Ships. Annex VI entered into force on May 19, 2005. Furthermore, the EPA is proposing to include two new, more stringent tier emissions standards to go into effect in 2011 and 2016 modeled after the IMO Annex VI.

Individual states have initiated efforts to strengthen the Clean Air Act emission regulations.  The California Air Resources Board (CARB) implemented requirements that all oceangoing vessels utilize low sulfur fuel within 24 miles of the California coastline.  The following month, the Ninth District Appeals Court ruled against CARB, stating that the federal preemption powers of the Clean Air Act superseded state law.  CARB is preparing new regulations to again require low sulfur fuels that might satisfy the Court’s concerns.  However, as is the case with ballast water discharges, the issue is international in nature and cannot be mitigated through conflicting state by state regulations.