By Robinson Shaw One large ocean vessel, such as this cargo ship in San Francisco Bay, spews more pollutants than 2,000 diesel trucks, according to a Bluewater Network report. Big ocean vessels are the dirtiest source of transportation, leaving trails of smog across the world's most heavily plied shipping routes and clouds of crud in major ports, according to a report from the Bluewater Network. The report, a compilation of several studies, concludes that emissions from large ships significantly threaten the health of people living in major port areas in the United States. The emissions also contribute to climate change across the world's oceans, according to Bluewater.
Big ships are more energy-efficient than other forms of transportation such as trucks or trains.
However, a paucity of emissions regulations from the U.S. Environmental Protection Agency and international regulatory agencies have allowed big vessels to become leading emitters of nitrogen, sulfur oxide and diesel particulate. Oil tankers, container and cargo carriers, and cruise ships, all labeled Category 3 by the EPA, run on bunker oil, the dirtiest and least expensive form of fuel, according to Bluewater. Bunker oil, the residue of high-grade fuels, contains high concentrations of toxic compounds banned from use in many other industries. The fuel contains up to 5,000 times more sulfur than diesel fuel. The pollution is different from particulate pollution form trucks because that's dispersed all over the place, trucks spread out their toxic affect over distance, ships have dedicated routes and ports.