The US 9th Circuit Court of Appeals ruled that California can't regulate exhaust from ships -- even in Long Beach Harbor and San Francisco Bay -- because the EPA has that authority. Not much of a surprise, since California needs permission from the EPA even to regulate emission from cars. Ships pass though the Santa Barbara Channel by the dozens each day. International law governs these ships; involvement by the state is tricky. Passing though the channel, rather than outside the islands, cuts a lot of miles off a voyage from Asia. And every mile burns up lots of oil.
A local furniture manufacturer told me that it costs about $8 to ship a futon frame to China and back, via one of these shipboard containers. It's hard for local companies to compete with the lower costs of labor and looser environmental regulations over there.