@afewbugs @sheffieldmaskbloc @maskblocorg There was some testing earlier of 3M masks (I think they were 8210's, which have been made forever) which have been sitting on a shelf for like 10 years and they tested them on lab grade particulate machinery and found the performance was barely degraded compared to a brand spanking new mask. The melt blown layers just do not go bad and the only real risk point were the rubber straps. I'd have absolutely no hesitancy about using these masks.
