KF94 is one of the grades given to Korean health masks. 'KF' stands for 'Korean Filter'. Korean masks must be certified by KFDA and will be rated KF80/94/99 depending on their performance. The numbers quantify the filter performance of the mask. The higher the KF80/94/99 number, the higher the blocking rate. For example, KF80 blocks more than 80% of the average paricle si ...View more