It is 4 layers of filter - Fiberglass, Paper, Pre-filter, Carbon Filter.
OK, before you laugh, it works...or so I thought.
After just a single 20 minute roast (and what I thought was pretty good odor & smoke suppression), my neighbors angrily confronted me this evening.
Long story short, I think
any hint of smell will get me into trouble. I fear even the more advanced designs will not do enough to completely rid the air of coffee smell, so while it was fun while it lasted, I think I am going to look for a good friend to "host" my roaster - I know someone who has the same roaster
A few things revealed themselves in the design. For one thing, the plastic hose got fairly warm and the metal blower body got very hot - I don't think it was designed to handle air of that temp. I also thought of little sparks (which happened today), could easily cause problems either in the filter or downwind somewhere, especially with that velocity of air.