Phillip W. Clapp, Emily E. Sickbert-Bennett et el published a study in JAMA regarding efficacy of various masks in COVID pandemic.
INTRODUCTION
Centers for Disease Control and Prevention (CDC) emphasizes the importance of wearing face masks that properly fit the face to slow the spread of SARS-CoV-2. Masks are a proven means to prevent the spread of SARS-Cov-2, however, not all masks may be equal in this regard. Efficacy of various masks were tested in this study.
METHODS
A generator that produced particles with a median diameter of 0.05 µm was used. They tested FFE(fitted filtration efficiencies) for different masks while varying the humidity and temperature within a chamber. The test volunteer completed a series of bodily movements in the chamber to validate FFE in different positions. All masks were tested on a single man, who weighed 165 lb and measured 5′ 10″ tall. The male volunteer had no beard.
RESULT HIGHLIGHTS
- The N95 respirator achieved an FFE of 98.4%. N95 respirators that had expired or that had been sterilized with ethylene oxide and hydrogen peroxide were still highly effective.
- KN95 respirators, many of which are produced in China, were substantially less effective, with FFE of 53.2% to 85.1%.
- 3-layer cotton mask with ear loops = 26.5%
- Polypropylene mask with fixed ear loops = 28.6%
- Single-layer polyester gaiter/neck cover (balaclava bandana) = 37.8%
- Single-layer polyester/nylon mask with ties = 39.3%
- 2-layer nylon mask with ear loops (without aluminum nose bridge) = 44.7%
- Cotton bandana worn “bandit style” = 49%
- Cotton bandana folded in a rectangle per Surgeon General’s recommendation = 49.9%
- 2-layer nylon mask with ear loops (with aluminum nose bridge) = 56.3%
- Surgical mask with ties = 71.5%
- 2-layer nylon mask with ear loops (with aluminum nose bridge and 1 insert) = 74.4%
- 2-layer nylon mask with ear loops (with aluminum nose bridge and no insert; washed once) = 79%
- The FFE for the standard medical procedure mask with ear loops were as follows:
- No alteration = 38.5%
- Loops tied and corners tucked back in = 60.3%
- Secured with ear guard = 61.7%
- Secured with 23-mm claw-style hair clip = 64.8%
- Secured with 3 rubber bands to fix the mask = 78.2%
- Secured with a 10-inch segment of nylon hosiery = 80.2%