I came across this easy to understand (even for my older brain) article while trying to understand some of the terms used.

http://emag.medicalexpo.com/which-masks-actually-protect-against-coronavirus/

My take away: A surgical mask protects others from what is expelled by the wearer, but will not protect the wearer from airborne viruses. A respirator of the proper type, if properly fitted/sealed, does protect the wearer from a given percentage of airborne viruses. I assume the respirator would also protect others from expelled aerosols.

I would think a homemade mask would be most likely to function like a surgical mask than a respirator, but I could be wrong.

Purely as it pertains to dust, because for me excessive dust can lead to real breathing problems, I finally gave up on trying to use disposable respirators because they leaked and tended to fog up my glasses. I invested in a good 3M half face respirator with replaceable cartridges. The one that directs exhaust downward. It has worked very well, though in hot weather it can become a bit warm.

Very recently I purchased an RZ cloth half face respirator with reusable filters with the hope that they'll be more comfortable and work just as well. It gets great reviews from the woodworking community. I haven't had the chance to use it yet, and now I hear it is impossible to purchase replacement filters ... for now.