Here’s a bit of good news: I was trolling through EPA’s Toxics Release Inventory for some data on pollution trends, and came across this for King County, Washington, the home county of Seattle.

King_county_triair2 The upshot: since reporting requirements began in 1988, toxic air emissions from major facilities in King County have fallen by almost 90 percent.

Mind you, this isn’t the complete story. Not all facilities that pollute have to file reports with the EPA. Also, not all chemicals are covered in this graph—some compounds have been added since 1988, and some potentially hazardous compounds aren’t covered by reporting requirements. Plus, this doesn’t cover emissions from cars, trucks, or other mobile sources.

And the King County’s pollution decline may be less impressive than it seems at first blush. Some of the decline may have been the result of “outsourcing” pollution to other parts of the state, or other parts of the world. And perhaps most importantly, this line represents the total volume of pollution, not its total toxicity. The toxicity might have fallen more slowly (or quickly, for that matter) than the volume—but that’s much harder to figure out.

Still, despite all those caveats, it’s a pretty impressive feat, no? Fifteen years of “sunshine”—in which major facilities are required to face public scrutiny for how much they pollute—and they manage to cut the annual volume of pollution to a tenth of its former level, even as the county’s population and economy grew rapidly. This gives me hope, and some confidence that even further reductions in pollution are possible, if not inevitable. As the song goes: “Please don’t take my sunshine away.”