Name:   GoneFishin - Subject:   Florida Atlantic Univ Visual On Mask and Coughing Date:   7/1/2020 11:08:27 PM

Interesting Coughing With and Without Mask

Research from Florida Atlantic University’s College of Engineering and Computer Science, just published in the journal Physics of Fluids , demonstrates through visualization of emulated coughs and sneezes, a method to assess the effectiveness of facemasks in obstructing droplets. The rationale behind the recommendation for using masks or other face coverings is to reduce the risk of cross-infection via the transmission of respiratory droplets from infected to healthy individuals.

Researchers employed flow visualization in a laboratory setting using a laser light sheet and a mixture of distilled water and glycerin to generate the synthetic fog that made up the content of a cough-jet. They visualized droplets expelled from a mannequin’s mouth while simulating coughing and sneezing. They tested masks that are readily available to the general public, which do not draw away from the supply of medical-grade masks and respirators for healthcare workers. They tested a single-layer bandana-style covering, a homemade mask that was stitched using two-layers of cotton quilting fabric consisting of 70 threads per inch, and a non-sterile cone-style mask that is available in most pharmacies. By placing these various masks on the mannequin, they were able to map out the paths of droplets and demonstrate how differently they perform.

Results showed that loosely folded facemasks and bandana-style coverings stop aerosolized respiratory droplets to some degree. However, well-fitted homemade masks with multiple layers of quilting fabric, and off-the-shelf cone style masks, proved to be the most effective in reducing droplet dispersal. These masks were able to curtail the speed and range of the respiratory jets significantly, albeit with some leakage through the mask material and from small gaps along the edges.

Importantly, uncovered emulated coughs were able to travel noticeably farther than the currently recommended 6-foot distancing guideline. Without a mask, droplets traveled more than 8 feet; with a bandana, they traveled 3 feet, 7 inches; with a folded cotton handkerchief, they traveled 1 foot, 3 inches; with the stitched quilted cotton mask, they traveled 2.5 inches; and with the cone-style mask, droplets traveled about 8 inches.