Recognizing they can’t grow unless they clean up, the huge ports of Los Angeles and Long Beach will soon unveil a $2 billion effort to address the incredible air pollution they produce every day. According to today’s Washington Post, the two ports that account for 40% of the nation’s container trade will launch a plan next month to “reduce particulate matter by 81 percent and nitrogen oxides by 62 percent in five years.”

And it sounds like it is needed; incomprehensibly, the L.A. port alone emits daily the equivalent particulate matter and nitrogen oxide produced by a half million cars, a typical refinery, and a typical power plant combined.

But looking at the numbers, it starts to make sense.

There are 16,300 trucks, many of them old and dirty, that move the contents of those containers to local distribution hubs. Some 500,000 work the shores. The two ports now handle 16 million 20-foot containers and expect that number to double by 2020.

According to John Pomfret’s reporting, the ports’ past efforts to expand have been stymied by lawsuits based on their poor environmental performance. According to the head of the L.A. port, “We realized it was either clean up the air or lose business.”

So props to NRDC, one of the initiators of the lawsuits.