is it possible that it is a activated carbon filter to reduce odors?
Is it a charcol filter
do they burn a lot of candles in the home? as that filter looks very sooty :neutral:
Sure as hell isn’t normal dust, belly button fluff & pet hairs
Maybe its one of these?
If they have a printer or copier in the same room, that could be the source of all that black powder. Hard to believe, but I remember a case like that, right here on this MB. Someone was printing brochures.
Yup, that’s a fact…
Do the filters start out black (charcoal impregnation)?
Is there smokers in the condo?
Do they burn candles? Candles can produce large amounts of soot.
A test that can be done is close off the register in the bathroom and cover with towel. Take white plastic or styrofoam plates and peel off the stack and place around the lit candle and close the door. Check in one half hour if there is soot on the plates then the candle is the source.
Could be grease; lots of frying smoke from cooking on the stove.
Might be time to get the ducts cleaned…