The report said double masking – a combination of a cloth mask and a medical procedure mask – blocked 92.5% of cough particles. (Centers for Disease Control and Prevention)“These laboratory-based experiments highlight the importance of good fit to maximize overall mask performance,” the report continues. “Medical procedure masks are intended to provide source control (e.g., maintain the sterility of a surgical field) and to block splashes. “The data in this report underscore the finding that good fit can increase overall mask efficiency,” the report concludes. Continued innovative efforts to improve the fit of cloth and medical procedure masks to enhance their performance merit attention.”