I advised on an installation in a Men's Shed that had rudimentary dust extraction and some members who suffered from Asthma were forced to leave the building due to poor dust control. Using the parameters I outlined above we were able to reduce the dust to almost ambient levels mainly due to the automatic blast gate system we developed. I would advise an auto BG system for ultimate dust control and Alan L. can attest to how much difference it makes. As I said above the overall result is not about using the best dust extractor but rather having the installed system work at peak efficiency. The big advantage we have in Australia is 99% of DE ducted systems exhaust to atmosphere and thus no filters.