The protection against viruses depends on the particle size of the aerosols containing infectious viruses. The sizes of these virus-containing particles differ from just the naked virus diameter (0,02–0,03 µm) to the sizes of the carrier particles. According to a study of the influenza virus, the virus-containing particles vary largely in size and 5% of the particles where larger than 4 µm, 75.5% was 1–4 µm and 19.5% smaller 1 µm. In another study of FMDV, 65–71% of the virus-containing particles were over 6 µm in diameter, 19–24% was 3 - 6 µm and 10–11% were under 3 µm.
The Urban Air Mask 2.0 and Lite Air Mask is tested and certified for 98% protection against particles down to the size of 0.3µm and because of this, the mask will protect you against virus-containing particles that are larger than 0.3µm.