Los Angeles Mayor James Hahn has announced an agreement in which several of the largest shipping companies in Asia will work with L.A. to clean up air quality in the city’s port. Last year, the port received 2,200 cargo ship visits, each burning about 14 tons of heavy bunker fuel. Under the new plan, the ships will shut off their engines while docked and plug into the city’s power system, helping to reduce a significant source of pollution in the region. The program would be the largest of its kind in the world. Some local activists predicted, however, that the port’s fast expansion would undermine the benefits of the project within a year or two.