There has been a study! It didn't cover beards longer than 10 mm, however. Short answer: not as good as an N95 without a beard, but better than cloth. https://

There has been a study! It didn't cover beards longer than 10 mm, however. Short answer: not as good as an N95 without a beard, but better than cloth. https://pubmed.ncbi.nlm.nih.gov/34006963/ https://pubmed.ncbi.nlm.nih.gov/34006963/