Reply #236: Good Eye, Jane. I just noticed those bands today, wondered what they

[petgoat]

were. One possibility then: that the dust is being blown out the air
intake from a heating system? It's dust from the ductwork? Otherwise,
yes, the mechanical room seems an ideal place to plant explosives--
except that a sharp-eyed engineer from Berkeley might look at some
pictures four years later....

I'll repeat my question. What's the confetti down near the bottom of
the picture? Under the red arrow.