Dan
Tiny dead skin cells when they flake from your body. Its leaking because the drain that carries the condensation from the coil of the aircon is blocked. And no..its only moisture that has condensated on the coil from the air. To clean the drain remove the main cover of the A/C that hold the filters (involves removing screws). Find the catchment area at the bottom of the coil (the big finned aluminium thing) look for a hole at one end and push a coat hanger or pipe cleaner down it. Pour water on the coil and watch it its carried away. Repeat till clear. Legionaries disease is only caused in bodies of stored water which is heated and cooled (or visa versa) in an open or closed cyclic system.

calical
ertert

Exit
dirty air circulating inside your room causes the filth. if you live in a very dusty place, like desert or something, then this has to be expected. if your room has no exhaust, then dirty air from toilets will cause the filth. try cleaning your filter a lot more regularly than 6 months to maintain efficiency

Sting Ray Daddy
The leaking is called condensation and happens with all a/c systems. Make sure you have good drainage the water can cause legionaries disease. The dirty filter is normal clean every 30 days.

William B
no other than a sore throat,from the dust

Polar Bear
UGH!! Change the filter every 30 days!!! To answer your query: yeah, its dead skin & every kind of particular contaminate your inside environment can generate....