On January 1, 2015, two sets of regulations became effective to help reduce air pollution: one involving large oceangoing ships and another involving US locomotives.
The shipping regulations come from the International Maritime Organization (IMO), a body under the United Nations. Thanks in part to hard work by my former NRDC colleague Rich Kassel, the IMO enacted a rule restricting the sulfur content of fuel for most oceangoing ships to 1,000 ppm sulfur in certain areas called Emissions Control Areas (ECAs); the current IMO limit is 35,000 ppm. There is an ECA for the United States that extends 200 nautical miles off our coasts. Because sulfur in marine fuel is the largest factor in emissions of polluting particulate matter from ship engines, this dramatic reduction will help reduce air pollution in port and coastal areas in the US and in northern Europe which also has two ECAs. It has been suggested that these new regulations could also lead to the use of more fuel-efficient ships. You can find a comprehensive FAQ for the new IMO regulation here.
Here in California, thanks to our Air Resources Board we have had an ultra-low sulfur marine fuel rule in place for years, but only out 24 nautical miles from the coast. The new IMO rule will be an improvement, but California's air quality is still so bad that much work remains to be done—especially in communities near major ports, rail facilities and truck routes. NRDC has worked for years, locally and nationally, to come up with solutions for air quality and health problems associated with cargo movement.
With respect to railroads—a major source of diesel particulate pollution in California—the new locomotive regulation comes from the US EPA and regulates pollution from new (and some remanufactured) locomotive engines sold in the US. You can see the details of the new "Tier IV" locomotive engines in this confusing table. If you read across the table, for example under "line haul" which means long-distance trains, you can see that very substantial reductions are required in emissions of NOx (oxides of nitrogen), which is a precursor of smog, and particulate matter (soot) over the earlier Tier III locomotives. The major railroads buy hundreds of new locomotives every year and so the hope is that the heavily-polluting older locomotives will quickly be phased out.