Regular face masks gibe little or no protection apart from being a physical barrier against debris.
As soon as the mask becomes moist with breath vapour it becomes a two way street for viruses and bacteria, the theatre masks we wear are effective for twenty minutes at the very most and then it's recommanded to change them.
Makes me laugh when I see tourists in London wearing them..
When Swine flu was around and we got a call to go to ED to see a suspected case we were issued these massive masks with big filters on each side.
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