PMC:7780429 / 10511-10682 JSONTXT

{"project":"LitCovid-sentences","denotations":[{"id":"T68","span":{"begin":0,"end":171},"obj":"Sentence"}],"namespaces":[{"prefix":"_base","uri":"http://pubannotation.org/ontology/tao.owl#"}],"text":"The surgical mask was used by 208 (79.7%) of those surveyed, and the filter mask (FFP2 or KN95) was used by 53 (20.3%), with no difference in the mean time of use 7.0 (SD:"}