“…Subsequent studies, in which not only surgical masks made of gauze and muslin but also ones made of paper, foam, and synthetic materials were evaluated, resulted in filter efficiencies ranging from the teens to nearly 100% (Brosseau, McCullough, & Vesley, 1997;Ford & Peterson, 1963;Ford, Peterson, & Mitchell, 1967;Miller, 1973Miller, , 1995Rogers, 1980). The findings of other studies in which surgical masks were evaluated (with some reported to have highly efficient filters) have emphasized that a secure face seal is essential for preventing infectious particles from escaping (as well as entering) at a mask's edges (Ha'eri & Wiley, 1980;Johnson, Martin, & Resnick, 1994;Pippin, Verderame, & Weber, 1987;Tuomi, 1985). Researchers, who have studied the aerosols and spatters produced during some dental procedures and the blood aerosols and spatters generated during surgeries, defined the size of spatter droplets to be 50 m and larger (Heinsohn & Jewett, 1993;Miller, 1973).…”