Captain Al:
I just put it on my bench, pulling the dust away from me. Generally I switch it on no matter why I do, sanding, working with CA glue and epoxy, soldering. when sanding, I always turn the voltage up to 12v to increase the air flow in order to filter as many air bound particles as possible.
Normally, I keep my purifier runs @ 7- 9v , less air flow and a bit quieter.
Mike Y:
brushless PC cooling fan is very quiet.
but when the air is pulling through the filter, that is going to generate some wind noise.
My Purifier's Noise level @12v : (65-70 dB)
brushless Fan without filters : ( 55-60 dB)