1 single KN95. KN95 is an industry standard and means that the mask provides the intended effectiveness of filtering 95 percent of particles with a mass median diameter of 0.3 micrometers. Therefore, this mask can protect you well from PM10, PM2.5, and even smaller particles. It can filter out air pollutants, pollen, bacteria and germs, smog, automobile exhaust and smoke, odor and fragrance, and animal allergens.