The adopted rules take effect in 2012, and by 2015, will require harmful air pollution from ships in a low-pollution zone known as an Emission Control Area to decline by 80 percent or more. The law will apply to large ships such as container ships, oil tankers, and large cruise ships.

The US Environmental Protection Agency (EPA) estimates that by 2030, the implementation of these limits on ship air pollution and related regulations will prevent up to 31,000 premature deaths, 1.5 million work days lost, and more than 5 million cases of acute respiratory symptoms. The health benefits could be worth $270 billion.

Friends of the Earth spent ten years working to put these protections in place, beginning with a legal challenge initiated in 2000. The environmental group praised the ruling, calling it a major victory.