To test whether face masks work in blocking the virus from being transmitted among people, the study measured how much S-CoV-2 is breathed into the air and tested how much less virus people sick with COVID-19 exhaled into the air after putting on a cloth or surgical mask.
Face coverings significantly reduced virus-laden particles in the air around the person with COVID-19, cutting the amount by about 50 per cent, the researchers found.
However, the loose-fitting cloth and surgical masks didn’t stop infectious virus from getting into the air, they said.
The “Alpha” variant (we are now at Delta) put 43 to 100x more viral particles in to the air than did the original virus.
The study authors say we now need to use real high filtration, tight fitting masks, not cloth facial coverings.