Source-linked AI summary
Visualizing droplet dispersal for face shields and masks with exhalation valves
Siddhartha Verma, Manhar Dhanak, John Frankenfield
TL;DR
As face shields and masks with exhalation valves are increasingly substituted for regular masks, the paper uses qualitative visualizations to examine how they impede droplet spread. The visualizations show that droplets can disperse widely around face shields and that many pass unfiltered through exhalation valves, suggesting plain regular masks may be preferable for restricting aerosolized droplets.
Problem
As face shields and masks with exhalation valves are increasingly substituted for regular masks, the paper examines how effectively these alternatives impede respiratory-droplet spread.
Source: pp. 1–2Method
The authors visualize cough-like jets from a manikin using water-glycerin droplets and laser sheets to observe their spatial and temporal spread.
Source: p. 2Results
Face-shield droplets can disperse widely, while a large number of droplets pass unfiltered through an exhalation valve, reducing source-control effectiveness.
Source: pp. 3–4Takeaways & Limitations
The visualizations suggest plain regular masks may restrict aerosolized droplet spread more effectively than face shields or masks with exhale valves.
Source: p. 4In a minimally disturbed environment, droplets showed no significant gravity-driven settling within the observed timeframe.
Source: p. 2
Abstract
from arXiv · showhide
Several places across the world are experiencing a steep surge in COVID-19 infections. Face masks have become increasingly accepted as one of the most effective means for combating the spread of the disease, when used in combination with social-distancing and frequent hand-washing. However, there is an increasing trend of people substituting regular cloth or surgical masks with clear plastic face shields, and with masks equipped with exhalation valves. One of the factors driving this increased adoption is improved comfort compared to regular masks. However, there is a possibility that widespread public use of these alternatives to regular masks could have an adverse effect on mitigation efforts. To help increase public awareness regarding the effectiveness of these alternative options, we use qualitative visualizations to examine the performance of face shields and exhalation valves in impeding the spread of aerosol-sized droplets. The visualizations indicate that although face shields block the initial forward motion of the jet, the expelled droplets can move around the visor with relative ease and spread out over a large area depending on light ambient disturbances. Visualizations for a mask equipped with an exhalation port indicate that a large number of droplets pass through the exhale valve unfiltered, which significantly reduces its effectiveness as a means of source control. Our observations suggest that to minimize the community spread of COVID-19, it may be preferable to use high quality cloth or surgical masks that are of a plain design, instead of face shields and masks equipped with exhale valves.
DATA AVAILABILITY
The study reports that data supporting its findings are available within the article.
- Data supporting the study's findings are available within the article.Source: DATA AVAILABILITY · p. 4