Everyone should wear a mask when dealing with coronavirus pandemic globally, according to the US’s center for disease control (CDC) recommendations wearing the mask impacts the chances of virus spread.
It's intuitive and scientifically shown that wearing a face-covering can help reduce the spread of the novel coronavirus that causes COVID-19. But not all masks are created equal, according to the new University of Arizona-led research.
Amanda Wilson, an environmental health sciences doctoral candidate in the Department of Community, Environment, and Policy in the Mel and Enid Zuckerman College of Public Health, is lead author on a recent study published in the Journal of Hospital Infection that assessed the ability of a variety of nontraditional mask materials to protect a person from infection after 30 seconds and after 20 minutes of exposure in a highly contaminated environment.
When the researchers compared wearing masks to wearing no protection during 20-minute and 30-second exposures to the virus, they found that infection risks were reduced by 24-94% or by 44-99% depending on the mask and exposure duration. Risk reduction decreased as exposure duration increased, they found.
"N99 masks, which are even more efficient at filtering airborne particles than N95 masks, are obviously one of the best options for blocking the virus, as they can reduce average risk by 94-99% for 20-minute and 30-second exposures, but they can be hard to come by, and there are ethical considerations such as leaving those available for medical professionals," Wilson said.
The next best options, according to the research, are N95 and surgical masks and, perhaps surprisingly, vacuum cleaner filters, which can be inserted into filter pockets in cloth masks. The vacuum filters reduced infection risk by 83% for a 30-second exposure and 58% for a 20-minute exposure. Of the other nontraditional materials evaluated by the researchers, tea towels, cotton-blend fabrics and antimicrobial pillowcases were the next best for protection.
Scarves, which reduced infection risk by 44% after 30 seconds and 24% after 20 minutes, and similarly effective cotton T-shirts are only slightly better than wearing no mask at all, they found.
Other conditions that impact the risk of infection are the number of people around you and their distance from you, she said.
The size of virus-transporting droplets from sneezes coughs or even speech is also a very important factor. Larger, heavier droplets carrying the virus drop out of the air faster than smaller, lighter ones. That's one reason distance helps reduce exposure.
The study also showed that the more time a person spends in an environment where the virus is present, the less effective a mask becomes.
Masks protect the wearer and others in a number of different ways. Wilson said there are two "intuitive ways" that masks filter larger aerosols: mechanical interception and inertial impaction.
The model developed by Wilson and her colleagues included parameters such as inhalation rate - the volume of air inhaled over time - and virus concentration in the air.
