I've only recently ( 3 Years) started woodworking. I have a 30X40 Shop, with 1/3 'finished' ie Temp/climate controlled, the rest is at Mother Nature discression. I collectted enough dust makers that I need to invest in a good collector. I have an air cleaner, 1 Micron filter, for the finished portion ( Bench, rounter and Band Saw live here). The other 2/3 of shop has a lot of outside air. I've been told I need a 1 Micron filter on dust collector but I'm not sure its beneficial because of all the outside air. So the primary question I have is How much of a filter do I need for a shop area that is not climate controlled? I want the collector to be portable to use in finished portion when necessary. Thanks folks, I've been trying to come to a decision for over 6 weeks and I keep talking myself out of what I thought I'd decided. I should also clarify the 2/3 'unfinished' portion does have a concrete floor and is essentially water tight, with electricity, just not heated, cooled or insulated.