@Tony_Furniere @DirkMonsieur @thomas_spaas Ziehier, één van duizenden bronnen, te beginnen met de pestmaskers uit de middeleeuwen. Zelfs toen wist men al beter.

Researchers show what masks are most effective to prevent spread of COVID-19 https://t.co/cV35xlKqSi
@Tony_Furniere @DirkMonsieur @thomas_spaas Here, one of thousands of sources, starting with the plague masks from the Middle Ages. Even when they knew better.

Researchers show what masks are most effective to preventable spread of COVID-19 https://t.co/cV35xlKqSi
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