Now with certified industry leading 99.8% gt filter at 0.075μm, so filters not just bacteria (2.5μm) but also viruses (0.1-.3). Aviro gt filtered mask has a 3 layer filter which contains non-porous membrane. Certified protection efficiency- 99.84 cns 14755 z2125 - 2011. Aviro masks are treated with hei q viroblock with the inner and outer layers engineered with hei q viroblock from switzerland. This results in an washable anti-microbial surface which destroys pathogens when they come into contact with the fabric surface.