In 2016, the NASA published a study demonstrating that air purifiers equipped with HEPA filters could catch nanoparticles with a <0.1 μm diameter. As coronaviruses have a diameter varying between 0.08 and 0.2 μm, HEPA filters are thus efficient against them.
A report published by ANSES (The French Agency for Food, Environmental and Occupational Health & Safety) also proved that HEPA filters could retain most of the droplets masks could not. The EOLIS Air Manager professional air purifier, equipped with a HEPA H13 filter, certified according to the NF EN 1822 standard, is 99.6% effective against coronaviruses.