For the purposes of the corona virus outbreak, there are three main types of masks: respirators, surgical masks, and fabric, or homemade, masks. N95 respirators are considered the gold standard for those on the frontlines. When worn properly securely fitted to a wearer face, they offer protection from about 95% of small particles (0.3 microns in size) and large droplets. Individual corona virus particles are smaller than this. But when they are coughed or sneezed up, they likely travel in small clumps of spit and mucus.
The WHO and the CDC only recommend N95s for health care workers at the greatest risk of virus exposure, such as those who test patients for COVID-19 by swabbing their noses or mouths or those who connect patients to respirators. In an ideal setting, N95s are only worn once and then tossed out. But due to supply shortages, health care workers are having to repeatedly wear the respirators, raising questions about whether the masks are getting contaminated from repeated exposures and removals. No one is recommending the public wear N95 respirators.
But still, they are far from perfect.
Those materials do not keep the tiny viral particles from entering your breathing zone from behind the face mask, said Diane Lauricella, a Norwalk-based independent environmental consultant and a former health and safety officer for the Department of Energy and Environmental Protection. These homemade designs can also be bolstered, though, by adding additional low-cost, household screens, Lauricella said. Coffee filters, dressmaker facing, vacuum bags and feminine products can all be cut and fastened into a mask to provide additional protection. But these items may only slightly improve an imperfect mask. Lauricella said its incumbent on the government to advise people of the limitations of homemade masks.
According to Jacqueline Vernarelli, a nutritional epidemiologist at Sacred Heart University, the usefulness of a homemade mask depends less on the material of the covering and more on how its worn. We know that asymptomatic individuals can unknowingly spread the illness, so telling everyone to wear a mask prevents accidental spread, Vernarelli said. Wearing any face covering, whether a bandanna, a construction mask, a surgical mask, or even a neck buff, is better than nothing, provided it covers the nose and mouth.
According to the study, Kelley said, N95 masks provided 25 times the protection of surgical masks and 50 times the protection of cloth masks. The study also found that cloth masks reduced admitted particles by one-fifth, surgical masks reduced it by half and N95 reduced particles by two-thirds. Citing this data, Kelley said those wearing homemade masks should not feel overly comfortable when out in public.