Ok here is the reply from RZ.
Stephen,
Thank you for reaching out. We are very excited to currently be in the final testing phase for NIOSH approval. Until this is completed, we are unable to recommend our masks for use with silica. When working with silica, OSHA recommends using an N95 or greater mask. Testing for these ratings has many stages and is where we have received our published filter test results. So far in the process, our filters have been tested to block 99.9% of particulates down to .1 micron. An N95 or N99 rating means that a mask filters at least 95% or 99% of particulates down to .3 micron. However, because we are still in the testing phase, we have not yet received a rating.
If there is anything else you need, please let us know. Thank you!
It seems as though it's coming? Their customer service seems to be GREAT!! I emailed them last night and already recieved a response!