Japan researchers show masks do block coronavirus, but not perfectly

FILE PHOTO: Passengers wearing protective face masks, following an outbreak of the coronavirus disease (COVID-19), are seen at a station after the government announced the state of emergency for the capital following the disease outbreak in Tokyo, Japan April 8, 2020. REUTERS/Issei Kato

TOKYO (Reuters) - 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 nebulizer, simulated coughing and expelled actual coronavirus particles. The other mimicked natural breathing, with a collection chamber for viruses coming through the airway.