Japanese researchers showed that masks can offer protection from airborne coronavirus particles, but even professional-grade coverings can’t eliminate contagion risk entirely.

Scientists at the University of Tokyo built a secure chamber with mannequin heads facing each other. One head, fitted with a nebuliser, simulated coughing and expelled actual coronavirus particles. The other mimicked natural breathing, with a collection chamber for viruses coming through the airway.

A cotton mask reduced viral uptake by the receiver head by up to 40 per cent compared to no mask. An N95 mask, used by medical professionals, blocked up to 90pc. However, even when the N95 was fitted to the face with tape, some virus particles still sneaked in.