Well............when I get it done the pictures will show it better. For now though this is kind of the idea.
I have a filter above the main storage room door. I keep that door closed so I keep the storage clean. It is high to pull the warm ceiling air. It feeds both the air handler and paint supply vents. There is another filter at the air handler entrance, and one inside the air handler. Hopefully that helps to eliminate saw, and grinder dust.
Soon I will have my dust collector plumbed so that I can choose to vent in the shop, or close a gate and vent outside. Complicated, but it allows me to control my air consumption and dispose of any nasty stuff outside. (also allows me to keep the temperature in the shop where I want it).
As far as the paint booth is concerned. I have a 5500 cfm blower setup that will be mounted in the storage room next to the air compressors. Air will flow from the shop, across the loft and through the vents. (this allows me to place a heater if I need to warm the air in the loft) I will have 3 (possible 6, but for now 3) 20x20 vents in the ceiling near the rear of the paint booth (they will be furnace filter style vents so changes are easy). The air then draws through the booth to the front wall, I will collect it in 2 20x20 vents (again furnace filter style grills) with tack filter paper and mesh filters). Then on the outlet of the fan it will be plumbed so I can vent it outside during paint operations, and then I will also have a door with an activated carbon filter so that during gas off, I can circulate the air through the back room without ducting it outside and losing heat.........
Pictures will help when I get there. I hope to have the fan done soon, but I still have to finish the paint room of with metal.