Plastic face shields are almost totally ineffective at trapping respiratory aerosols, according to modelling in Japan, casting doubt on their effectiveness in preventing the spread of coronavirus. From a report: A simulation using Fugaku, the world's fastest supercomputer, found that almost 100% of airborne droplets of less than 5 micrometres in size escaped through plastic visors of the kind often used by people working in service industries. One micrometre is one millionth of a metre. In addition, about half of larger droplets measuring 50 micrometres found their way into the air, according to Riken, a government-backed research institute in the western city of Kobe.
This week, senior scientists in Britain criticised the government for stressing the importance of hand-washing while placing insufficient emphasis on aerosol transmission and ventilation, factors that Japanese authorities have outlined in public health advice throughout the pandemic. As some countries have attempted to open up their economies, face shields are becoming a common sight in sectors that emphasise contact with the public, such as shops and beauty salons. Makoto Tsubokura, team leader at Riken's centre for computational science, said the simulation combined air flow with the reproduction of tens of thousand of droplets of different sizes, from under 1 micrometre to several hundred micrometres.
Read more of this story at Slashdot.