WASHINGTON: Ships that travel on the world's oceans will have to clean up their emissions under new international air cleanliness regulations adopted on Thursday.

The International Maritime Organization set a global cap for the amount of sulfur in marine fuels to reduce the air pollution that plagues ports and coastal communities in the United States and worldwide.

Ships will have to burn diesel fuel containing 0.5 percent sulfur by 2020, down from an average of 2.7 percent now.

Countries wanting to accelerate the cleanup also can establish local or regional emission control areas off their coasts. Ships operating in those zones would have to meet 0.1 percent sulfur content in fuel by 2015, and all new ships would have to have engines that reduce nitrogen oxides by 80 percent.

The Environmental Protection Agency, which participated in the negotiations in London, said Thursday it will apply next year to make U.S. coastal waters emission-control areas. The agency is under a federal court order to issue regulations to reduce emissions from oceangoing ships by December 2009.

“This program between the sulfur reduction and the nitrogen oxides reduction from the engines will provide significant air quality benefits,'' said Margo Oge, director of the EPA's Office of Transportation and Air Quality.

Air pollution from ships contributes to acid rain, smog and haze. Oge said that 40 major U.S. ports, home to 87 million people, are in areas that violate air quality standards. Research also has shown that the pollution emitted by ships at port moves inland where it can worsen air quality.

Environmentalists hailed the action Thursday, but said the IMO, a United Nations agency with 168 member countries, also should tackle the gases from vessels that are blamed for global warming.