Today we learn via SFist, that after last week’s news of a radiation plume drifting across the Pacific from Japan, officials worked to make sure San Francisco’s network of rooftop radiation sensors was operational. Which it wasn’t because you know, air raid sirens at noon every Tuesday are way, way more important.

About a third of the sensors that serve as the nation’s first line of defense were busted last week. Still, we’re told there’s nothing to be alarmed about. It can’t be any worse than whatever power meter PG&E is currently installing outside your bedroom anyway.

We’re very reassured, as apparently was this tagger who left some “artwork” (the quotations cannot be emphasized enough) by a Muni shelter for the 38 bus on Geary at Leavenworth. So the rain might be radioactive today? So what, yo.