Ann, here's the link:
http://www.dustbeegone.com/dus...
It says it's good to 3 microns but my Dad talked to her and if you wet it, it's good to 1 micron. But she can't advertise that because they didn't do official testing on it like that. The lady who invented it runs a saw mill but Dad is telling me she used to run a t-shirt screening business. She used her t-shirt fabric skills and connections to create the mask. Dad works with this lady a lot and he says she personally fitted him for his mask.
They all use them and he's had his for at least four years.
