I use a system by SATA, the guys who make the rally good paint guns.
It is a constant fresh air system that hooks up to your air compresor,
designed to be work in paint booths. It can be seen he

http://www.sata.com/Produkte/produkt...-21&menu=05,15

The difference with my unit, and the one in the link is that on mine,
the filter is on the wall, inline with my SATA particulate, water and
oil filters. The only thing attached to me is the air hose. As an
added benefit of this system, there is no battery to go dead, and the
head/neck hood keeps the shavings off of me.
--
Nail a post to the Spalted Board. Free WW'ing software and forums.
Regular freebies! http://www.spaltedboard.com