DETROIT – Public health officials strongly recommend using face coverings to slow the spread of the coronavirus (COVID-19), but not all masks are created equal.
To demonstrate the differences between masks, researchers from the College of Engineering and Computer Science at Florida Atlantic University created a visual simulation.
Researchers weren’t trying to create the perfect model of droplet and aerosol spread through masks. They set out to create a practical and visual demonstration of the performance of three different masks -- one made from a folded handkerchief, one made from two layers of cotton fabric and a simple dome mask.
Using a mannequin head and fog maker to create a visible aerosol highlighted by a green laser, researchers created a simulated cough.
A light cough without any face covering spreads the aerosol mist a short distance, but a simulated heavy cough without a face covering expelled aerosol three feet away within two seconds and six feet away within 11 seconds.
They also showed the effect a light breeze had on the aerosol spread. While the breeze disperses the aerosol, it moves the particles downwind.
A folded handkerchief or bandana leaks a significant amount of aerosol through the face and at the top edge.
A homemade stitched fabric mask did a much better job of reducing the amount of aerosol spread into the air. The spray didn’t go much beyond three inches from the mannequin face. There was still leakage at the top of the mask.
Researchers used an off-the-shelf cone-type mask. Even though it was the same shape as some N-95 respirators, it wasn’t the same.
The amount of aerosol that penetrated the front of the mask traveled farther than the aerosol through the hand-sewn mask. There was again leakage from the top of the mask.