Using inexpensive and widely available tools, scientists have developed a simple approach to visually evaluate how effectively different types of masks prevent the spread of droplets that can contain SARS-CoV-2 virus particles, according to a new study.
While the authors note that their work is still in its early stages, and its method has so far only been tested in a small group of people, these preliminary, evidence-of-principle findings suggest that N95 masks, surgical or polypropylene makers of professional grade, and handmade cotton masks can all block a lot of the spray produced as carriers speak. However, bandanas and neck braces probably do not provide much protection because the researchers found that more drops are expelled by these materials – probably because the materials break up larger drops as they pass through the material, the researchers speculate. Emma Fischer and colleagues suggest that non-experts could easily build and operate this setup to assess masks at the community level, so that mask manufacturers could use the method to optimize mask designs, and training and community care organizations could demonstrate proper mask fitting procedures.
As nations worldwide have instituted mask mandates to curb the spread of COVID-19, global commercial suppliers have faced shortages in the face of unusual demand. To compensate, many people have become accustomed to homemade masks and mask alternatives, but these do-it-yourself versions have not been systematically tested. To evaluate the effectiveness of 14 different types of masks and other frequently replacing face masks, Fischer and others. design a simple approach in which one male speaker or, in some cases, four speakers wears each mask while standing in a dark closet. The speaker would say the phrase “stay healthy, people” five times in the direction of a laser beam, which emits light scattered from the drops during speech.
A camera of the phone recorded the drops and a simple computer algorithm counted them. The setup was intentionally designed to be simple and inexpensive so that it could be replicated by non-experts – the hardware it requires, including laser equipment, is usually available and can be purchased for less than $ 200. the researchers recognize the need for further testing, Fischer said and others.The findings suggest that N95 masks without valves blocked the droplets best dispersed, but surgical as well as polypropylene masks and handmade cotton face masks were also effective. Early findings suggest, however, that bandanas and neck fleeces (such as balaclavas) are likely to provide some protection.
“Our work was a demonstration of a simple measurement method, not a systematic mask study,” writes Martin Fischer, the corresponding author of the study, in a Q&A. “More work is needed to investigate variations in masks, speakers and how people wear them. We also want to extend our method to other driplet-generating actions, such as coughing and sneezing. Furthermore, we want to investigate effects of incorrect placement and damp saturation. ”
