Protecting healthcare staff from severe acute respiratory syndrome: filtration capacity of multiple surgical masks

Abstract

Guidelines issued by the Centers for Disease Control and Prevention and the World Health Organisation state that healthcare workers should wear N95 masks or higher-level protection during all contact with suspected severe acute respiratory syndrome (SARS). In areas where N95 masks are not available, multiple layers of surgical masks have been tried to prevent transmission of SARS. The in vivo filtration capacity of a single surgical mask is known to be poor. However, the filtration capacity of a combination of masks is unknown. This was a crossover trial of one, two, three and five surgical masks in six volunteers to determine the in vivo filtration efficiency of wearing more than one surgical mask. We used a Portacount to measure the difference in ambient particle counts inside and outside the masks. The best combination of five surgical masks scored a fit factor of 13.7, which is well below the minimum level of 100 required for a half face respirator. Multiple surgical masks filter ambient particles poorly. They should not be used as a substitute for N95 masks unless there is no alternative.

Comparison of Filtration Efficiency and Pressure Drop in Anti-Yellow Sand Masks, Quarantine Masks, Medical Masks, General Masks, and Handkerchiefs

“…In view of the possibility of airborne transmission, current guidelines issued by the Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) state that health-care workers should wear N95 masks or higher-level protection during all epidemic situations (Derrick and Gomersall, 2005). However, no strict regulation exists for the filtration efficiency and pressure drop for surgical or dental masks worldwide.…”

Protecting staff against airborne viral particles: in vivo efficiency of laser masks

“…This device generates a saline Based on data from a previous study, it was calculated that a sample size of eight would have 80% power to detect a 50% improvement of either the laser mask or the FFP2 respirator over the surgical mask. 7,10 Comparisons between two types of mask were made using paired t-tests. P values for multiple comparisons between types of mask were adjusted using the Holm stepdown approach (STA version 8.0, College Station, Texas, USA).…”

SARS, avian flu, bioterror: infection control awareness for the optometrist

“…2 If splashes or direct coughing occurs, goggles should be worn. 19 Eyeglasses or contact lenses are not considered eye protection.…”

“…Surgical masks are not considered a substitute for an N95 or higher-rated mask and should be used only if there is no alternative. 19 Care must be taken with the removal of PPE. One may consider designating an area with adequate space within the office specifically for the task of PPE removal, so as not to contaminate the environment.…”