They have been tested for respirator filter efficiency only and were found to exceed 99% filter efficiency: https://www.cdc.gov/niosh/npptl/respirators/testing/results/...
But they are explicitly not NIOSH approved and as mentioned have an ear loop design whereas seemingly all approved masks go around the head. Wish I could edit/remove the original posting.
They have been tested for respirator filter efficiency only and were found to exceed 99% filter efficiency: https://www.cdc.gov/niosh/npptl/respirators/testing/results/...
But they are explicitly not NIOSH approved and as mentioned have an ear loop design whereas seemingly all approved masks go around the head. Wish I could edit/remove the original posting.