"Toller" wrote in message
...

I wear a dust even with both my high effeciecy cyclone dust collector
and an ambient air filter but I feel that my tool and surfaces in the
shop benefit at least a little from the air filter. I also use three
phase filtering on the ambient air system. 1. a 3M type furnace
filter, the 2. 5-20 micron filter then 3. the Hepa sheet and all three
get dirty after about 12 hours of contineous use. So I guess what
still have me puzzled is the fact that I AM capturing a lot of dust to
get out of the shop and is this not a good thing in the long run?

I think they are just saying it gives a false sense of security; rather
than
that it is doing harm.

I'm not qualified to assess the technical merits, but what it says is that
you might be doing more harm by continuously circulating improperly-filtered
air and keeping it stirred up vs. letting it (eventually) settle to the
floor.

todd