How a mask helps minimise COVID-19 spread
Large droplets (greater than about 125 microns in diameter) fall to the ground within about 2 metres, while turbulent clouds transport a mist of small aerosolized droplets over significant distances (approximately 5 metres).
A loosely fitted simple cotton cloth mask qualitatively changes the propagation of the high velocity jet, and largely eliminates the turbulent cloud downstream of the mask.
The spread of the ejecta is also changed, with large droplets trapped at mask surface
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