Demo of PMRB
The above video shows how PMRB type box works.
Old mask without cleaning and recharging.
I washed the mask and static charge was gone. After having dried it, I tested it. It behaved even worse than old masks. The readout on the PM meter raised quickly.
After having a washed mask recharged, it returned it to like new. It can block small smoke particulars and the readout on the PM meter raised slowly.