Scientists have experimented with non-medical grade masks, and found that well-fitted ones made from stitching two layers of quilting cotton fabric are the most effective in stopping the spread of cough and sneeze droplets, whereas bandana-style coverings "had little to no effect."
The study, published in the journal Physics of Fluids, used a laser to map out the paths of droplets as they were coughed and sneezed out of a mannequin head, and examined how different mask designs and materials altered these paths.
While the use of face masks is widely recommended by public health officials during the Covid-19 pandemic, relatively few specific guidelines pertaining to mask materials and designs are available, according to the researchers from Florida Atlantic University in the US.
"While there are a few prior studies on the effectiveness of medical-grade equipment, we don't have a lot of information about the cloth-based coverings that are most accessible to us at present," said Siddhartha Verma, a co-author of the study.
"Our hope is that the visualisations presented in the paper help convey the rationale behind the recommendations for social distancing and using face masks," Verma said.
In the study, the scientists found that loosely folded face masks, and bandana-style coverings had little to no effect on stopping droplet jets.
They said well-fitted homemade masks with multiple layers of quilting fabric, and commonly available cone style masks proved to be the most effective.
"Some leakage notwithstanding, these masks reduced the number of droplets significantly," the researchers noted in a statement to the press.
When without a mask, the scientists said, the mannequins were projecting droplets much farther than the six feet recommendation of social distancing guidelines.
"It is also important to understand that face coverings are not a 100 per cent effective in blocking respiratory pathogens," Verma said.
"This is why it is imperative that we use a combination of social distancing, face coverings, hand-washing and other recommendations from health care officials until an effective vaccine is released," he added.