0

On my office ceiling there are a few air vents. They are usually inactive, yet a few days per year (for some incomprehensible reason) they start working, and air flows in.

What concerns me is the strange material that lies just on top of the vent's cap; please see the pictures below. It looks like ash and disintegrates easily if pressed with two fingers.

Has anybody seen air vents made like this? Assuming that the black material serves as a filter, is it common (or was it common) to design filters like this?

Finally, can you say anything about the safety of this arrangement, in terms of presumed indoor air quality?

enter image description here enter image description here enter image description here

user1317811
  • 3
  • 2

1 Answers1

1

That is plasticized open-cell foam, used as an air filter. Such products "rot" and crumble apart with time. The reason for the rotting is diffusion of the plasticizer out of the resin from which the foam was blown. When this occurs, it cannot be repaired- the filter must be removed and replaced. Wear disposable gloves while doing this, as the rotten foam will be greasy and loaded with dirt.

niels nielsen
  • 15,513
  • 1
  • 15
  • 33