The expanding rail yards east of Los Angeles, brimming with foreign cargo from the area's two ports, are a brawny symbol of Southern California's growing stature as one of the world's great crossroads of international trade.
But the economic bonanza is exacting a rising price. Exhaust and soot from diesel locomotives, ships and planes are dirtying the air in neighborhoods from Wilmington to Commerce, threatening to undermine decades of progress toward healthful air.
Alarmed by the procession of smoke-belching freight trains rumbling out of the ports of Long Beach and Los Angeles -- their number is expected to double by 2020 -- Southern California's chief smog-fighting agency is seeking approval from the Legislature to impose a fee on locomotives that do not substantially reduce smog-forming emissions.
The fee proposal is part of a broader attempt by the South Coast Air Quality Management District to strengthen its authority over a variety of pollution sources, including the principal engines of global trade -- trains, ships and planes.
Last year, the Greater Los Angeles area experienced a smoggy relapse: 68 bad air days, a 28% increase from the previous year and nearly 50% more than in 2001. Last summer, air quality officials declared the first Stage 1 health alert since 1998. The public warning that the air was dangerous for everyone to breathe is one officials had thought they might never need to issue again.
"We're trying to shine a bright light on the railroads, because of the impact they are having on air quality in local communities," said Barry Wallerstein, the AQMD's executive officer, adding that the district was going to bring railroad companies "to the table, one way or another, and have a serious discussion about air pollution."
However, the legislation is strongly opposed by two powerful adversaries: Union Pacific Railroad and Burlington Northern Santa Fe Railway.
The railroads helped scuttle a similar bill sponsored by the AQMD last year that would have allowed the agency to place a pollution fee on ships, airplanes and trains. Such a move would almost certainly be challenged in court as a violation of federal laws that give Washington oversight over railroads because of their importance to interstate commerce.
The railroads, which haul an estimated $100 billion in goods out of the region every year, note that they are responsible for a relatively small share of Southern California's air pollution problems -- roughly 3% of smog-forming fumes.
