PMC:7435837 / 27160-27253
Annnotations
LitCovid-PD-CLO
{"project":"LitCovid-PD-CLO","denotations":[{"id":"T267","span":{"begin":51,"end":52},"obj":"http://purl.obolibrary.org/obo/CLO_0001020"}],"text":"filter at least 99% of airborne particles, leaving a gap for some particle penetration. These"}