Single use KN95 Face Masks Image via smartairfilters.com Please note this data is from a study into influenza transmission, looking specifically at the protection given to the wearers. However. Influenza may be a good virus particle to compare coronavirus to, as they are both transmissible through droplets and aerosol, both cause respiratory infection, and both are similar in particle size. Source for coronavirus (SARS-CoV-2) size is this paper, whilst sources for Influenza size are this paper (eventually published in Vaccine) What is the difference between KN95, FFP2 and FFP3? The most commonly discussed respirator type is N95. This is an American standard managed by NIOSH – part of the Center for Disease Control (CDC). Europe uses two different standards. The “filtering face piece” score (FFP) comes from EN standard 149:2001. Then EN 143 standard covers P1/P2/P3 ratings. Both standards are maintained by CEN (European Committee for Standardization). Respirator Standard Filter Capacity (removes x% of of all particles that are 0.3 microns in diameter or larger) FFP1 & P1 At least 80% FFP2 & P2 At least 94% N95 At least 95% N99 & FFP3 At least 99% Therefore, the closest European equivalent to N95 are FFP2 rated respirators, which are rated at 94%, compared to the 95% of N95. More detailed information about masks and resporators and their efficiancy to protect against coronavirus and COVID-19 can be found HERE Please note, for hygiene reasons we cannot accept returns on any face masks.   PPE