From Fast Company's design blog:
Clearly it’s some kind of pinko Canadian stunt, right? A passive-aggressive commentary on Americans’ conspicuous consumption? Wrong! Non-Sign II is the brainchild of the Seattle art and architecture firm Lead Pencil Studio. Even crazier: It was commissioned by the federal government, which usually regards high art the way one would a dead rat.
The sculpture's purpose is to promote the benefits of clean air, comment on the widespread nature of consumption, and according to Brandflakes, asks us to consider a less cluttered world. I think it's just cool that there's dead space in the middle of a highly-traveled landscape. It interrupts one's schema because it's so unexpected.
I have a love/hate relationship with advertising, though it's mostly love. When done well, it can illuminate and refine our desires, our passions, our values. When done badly, however, it feels like the static that surrounds this billboard, defining even more sharply how good some clear space feels.