The Bill, which gives powers to the US Coast Guard and the Environmental Protection Agency to inspect ships and enforce penalties, is designed to tackle the huge amounts of sulfur dioxides released by ships - more than that produced by all the world's cars, lorries and buses combined.
Marine diesel fuel, also known as 'red' diesel, differs from that found on the forecourt in terms of its sulphur content. Whilst 'city' diesel is now almost entirely low sulphur, containing as little as 10 parts per million (ppm) sulphur, 'red' diesel can easily contain 27,000 ppm sulphur. When burned with the fuel, sulphur creates sulphur dioxide, a gas which contributes to localised air pollution, acid rain and ozone layer destruction.
The new legislation will bring US shipping requirements into line with the rest of the world, which already follows the International Maritime Organization's standards introduced in 1997.
Last month, the Guardian revealed that international shipping accounts for twice as much pollution as aviation, some 800 million tonnes of carbon dioxide emissions every year, though these figures did not take account of distances travelled or goods transported.
This article first appeared in the Ecologist March 2007