Fact Finders: UA researchers look at best (and worst) materials for masks

KOLD FACT FINDERS: Best materials for masks

TUCSON, Ariz. (KOLD News 13) - You may be making one or buying one. Either way, experts say you should be wearing one in public.

A mask is now required in public places where you can’t practice social distancing in Pima County, but the kind of mask you are wearing could work better at keeping you safe as COVID-19 continues to spread.

“We know that the amount of time that someone is in a really contaminated environment effects their risk,” said Amanda Wilson, a University of Arizona environmental health sciences doctoral candidate in the Department of Community, Environment and Policy in the Mel and Enid Zuckerman College of Public Health.

Wilson is the lead author in a 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.

Researchers used computer models to compare wearing masks to wearing no protection during 20-minute and 30-second exposures to the virus. They found 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.

According to the study, N99 and N95 are some of the best options for blocking the virus. The masks can reduce average risk by 94-99% for 20-minute and 30-second exposures. The next best option is surgical masks.

When you are looking at nontraditional, household items, the study found vacuum cleaner filters, which can be inserted into filter pockets in cloth masks, reduced infection risk by 83% for a 30-second exposure and 58% for a 20-minute exposure. Wilson said you will want to check the manufacturer, as some have put out information regarding the use of filters for masks.

“Looking at pillowcases and looking at bed sheets, how does the increase in thread count effect the efficacy of filtering out these particles,” said Wilson.

Of the other 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.

“What if you’re exposed for thirty seconds to a really contaminated environment, versus twenty minutes, does that make a difference in terms of the infection risk reduction that you get? And we did see a pretty big difference,” said Wilson.

Other conditions that impact risk of infection are the number of people around you and their distance from you, she said in a press release from the University of Arizona.

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.

“Masks are definitely important, especially when you’re in public, but the best defense is to not be there,” said Wilson. “The best defense is to be home, if you can.”

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