A legal challenge to the enforcement of the regulation, filed by the Pacific Merchant Shipping Association (PMSA), was denied on 30 June by the Eastern District of California.

The regulation requires ships to use more refined fuel with lower sulfur content, and is being implemented in two steps. In 2009, MGO (marine gasoil) must have a sulfur limit of 1.5% (15,000 ppm), while MDO (marine diesel oil) would have a limit of 0.5% (5,000 ppm). In 2012, the limits for both fuels drops to 0.1% (1,000 ppm).

The requirement, adopted in 2008, will annually affect nearly 2,000 ocean-going vessels, both US- flagged and foreign-flagged, visiting California. Initially, 13 tons-per-day of toxic particulate matter emitted from the vessels’ diesel engines will be eliminated. Reductions will increase as the fuel sulfur content is progressively lowered through the regulation&rsqo;s phase-in.

The switch will eliminate about a 75% of the diesel PM, more than 80% of the sulfur oxides and 6% of the nitrogen oxides. In 2012, when the very low sulfur fuel is required, reductions of diesel particulate matter will be 15 tons daily, an 83% reduction compared to uncontrolled emissions. Sulfur oxides will be reduced by 140 tons daily, a 95% reduction and nitrogen oxides will be reduced by 11 tons per day, a 6% reduction.

Reducing ship exhaust will eliminate an estimated 3,600 premature deaths between 2009 and 2015 and lower the cancer risk by over 80 percent. In addition, the emission reductions will assist the South Coast Air Quality Management District meet its 2014 federal clean air requirements for fine particulate matter. The reductions are also needed for ARB to achieve its targeted 85% reduction of diesel PM by 2020.