Indistinguishable

Looking into the space above the ceiling and below the roof joists in a tenement:

The vertical surface past the studs on the left is the back side of a plaster-on-expanded-metal-lath partition; the bottom is the backside of a similar ceiling. There’s a lot of dust – a dust ocean rather than dust bunnies – on top of the ceiling; the black spots on the studs are dirt of some kind.

It’s amusing – in a “it gives me coughing fits” kind of way – how difficult it is to tell plaster from dust in this photo.