Efficacy of face masks, neck gaiters and face shields for reducing the expulsion of simulated cough-generated aerosols

Abstract

Face masks are recommended to reduce community transmission of SARS CoV 2. One of the primary benefits of face masks and other coverings is as source control devices to reduce the expulsion of respiratory aerosols during coughing, breathing, and speaking. Face shields have been proposed as an alternative to face masks, but information about face shields as source control devices is limited. We used a cough aerosol simulator with a headform to propel small aerosol particles (0 to 7 μm) into different face coverings. An N95 respirator blocked 99% of the cough aerosol, a procedure mask blocked 59%, a 3-ply cloth face mask blocked 51%, and a polyester neck gaiter blocked 47% as a single layer and 60% when folded into a double layer. In contrast, the face shield blocked 2% of the cough aerosol. Our results suggest that face masks and neck gaiters are preferable to face shields as source control devices for cough aerosols.

Relationship between human exhalation diffusion and posture in face-to-face scenario with utterance

“…However, persons infected with the COVID-19 may be asymptomatic; hence, it is important to recognize the risk of having conversational contact with seemingly healthy humans. In a previous study, airflow visualization measurement experiments were conducted to understand infection control more effectively; 16–20 however, most of them focused on sneezing and coughing. To verify the effects of wearing the mask, Verma visualized smoke diffusion by simulating exhalation based on a smoke generator and generated an airflow simulating cough from a mannequin wearing a mask and face shields.…”

Maximizing Fit for Cloth and Medical Procedure Masks to Improve Performance and Reduce SARS-CoV-2 Transmission and Exposure, 2021

“…to simulate a person coughing by producing aerosols from a mouthpiece (0.1-7 µm potassium chloride particles) (7). The effectiveness of the following mask configurations to block these aerosols was assessed: a three-ply medical procedure mask alone, a three-ply cloth cotton mask alone, and the three-ply cloth mask covering the three-ply medical procedure mask (double masking).…”

“…The first experiment assessed how effectively various mask combinations reduced the amount of particles emitted during a cough (i.e., source control) in terms of collection efficiency. A pliable elastomeric headform was used to simulate a person coughing by producing aerosols from a mouthpiece (0.1–7 μ m potassium chloride particles) ( 7 ). The effectiveness of the following mask configurations to block these aerosols was assessed: a three-ply medical procedure mask alone, a three-ply cloth cotton mask alone, and the three-ply cloth mask covering the three-ply medical procedure mask (double masking).…”

ADAPT: A Smart Mask for Active Defense Against Air-Borne Pathogens

“…Face coverings are effective in reducing the spread of the virus, even with high levels of exposure in closed spaces 2 . However, existing face masks do not adapt to changing exposure levels, i.e., only provide passive protection 3 . As a result, they are inefficient when these levels are unpredictable and fluctuate over time, which is generally the case.…”