Short URL: https://altppe.net/37bm
Although adding a procedure mask (mean [SD] FFE, 61% [13%]) over the cloth masks provided modest increases in their FFE (mean [SD] range, 55% [10%] to 60% [14%]), the overall performance was no different than wearing the procedure mask by itself. In contrast, wearing a procedure mask under the cloth face covering produced marked improvements in overall FFE (mean [SD] range, 66% [5%] to 81% [6%]).
