Most elegant. The big diesel air cleaner should process lots of air at low pressure, preventing blow through of particulates. I have always wondered about how much filter is required to keep out the anthrax and radioactive dust. I dis-assembled and reassembled a couple of a hospital grade hepa room filtration units, and the filter elements were always smaller than I would have expected. (Slow nights in the ER permit lots of time to experiment with the toys- I discovered that it is possible to warm up a hot dog using the defib paddles from a a LifePak 5 set at 200 Joules-and a defib pad will stick to a ceiling tile for 86 days...I was there when it fell off...)