As mandatory face coverings become more and more common, keep in mind, some are better at protecting from viruses than others.
When issuing their face covering guidelines, San Francisco specifically called out masks with one-way valves designed for “easier breathing”, warning that they allow for droplets to get out of the mask and potentially endanger others nearby. These valves are usually about the size of a coin on the side of the mask.
The CDC, and many other health departments and officials, urge wearing a mask to prevent the spread of the coronavirus because it can be spread through respiratory droplets. Those droplets are produced into the air when an infected person coughs, sneezes, talks, sings, chants, shouts, etc. They can then land on other people nearby or be inhaled by others.
The CDC recommends people wear a cloth face covering in public settings, to reduce the transmission of droplets into the air.
“There are no high quality studies regarding the use of masks with additional types of various filters placed in them or with ‘breathing valves.’ While widely marketed with various claims, these have not been studied at all and it is unclear if they help or hurt the overall filtration efficacy against microorganisms,” read a statement from Marc Sala, M.D., Assistant Professor of medicine in the Division of Pulmonary and Critical Care at Northwestern University’s Feinberg School of Medicine.
People are being asked to leave N95 masks (without a valve) and surgical masks available for medical staff and essential personnel who are coming into daily contact with many infected patients.
An N95 mask with an exhalation valve is not recommended because unfiltered air is sent through the valve and into the air, potentially carrying coronavirus droplets. “The presence of an exhalation valve reduces exhalation resistance, which makes it easier to breathe (exhale). Some users feel that a respirator with an exhalation valve keeps the face cooler and reduces moisture build up inside the facepiece. However, respirators with exhalation valves should not be used in situations where a sterile field must be maintained…” according to the CDC’s website.
Dr. Sala said testing has shown things like multiple layers of cotton fabric is better than a single layer, material of a higher thread count is more effective, and overall, “these studies emphasized the notion that if a mask doesn’t have a good fit (has gaps) its effectiveness is dramatically reduced.” Dr. Sala said even if the cloth mask is not ideal, it can still play a major role in preventing illness as more masks are worn by the population as a whole.
Bottom line, choose a fabric face covering that fits and is comfortable around your ears or head, and keep it on while in public, especially when social distancing is not possible, to protect you and the people around you.