Two masks may be better than one in reducing COVID exposure, CDC report finds
Wearing a cloth mask over a medical one may better armor people against the threat of coronavirus transmission, federal health officials said this week.
In a report released Wednesday, the Centers for Disease Control and Prevention found this type of double masking can substantially reduce a wearer’s exposure to potentially infectious aerosols. Adjusting a medical mask to fit more tightly can also provide similar protection, the report said.
Recent lab tests conducted with dummies found that both the cloth-medical mask combination and the tighter-fitting medical mask decreased exposure by about 95%, the CDC said.
That should come as little surprise, given that the coronavirus spreads most commonly in the air, when someone inhales infectious droplets or other tiny respiratory particles. Experts and officials have long noted that properly fitted masks and other face coverings can help prevent person-to-person transmission.
The CDC report is not without caveats, though. Its takeaways are limited by the nature of the experiments, which “were conducted with one type of medical procedure mask and one type of cloth mask” and “did not include any other combinations of masks, such as cloth over cloth, medical procedure mask over medical procedure mask, or medical procedure mask over cloth.”
Still, the report is the latest indication that, in some cases, two may actually be better than one — a particularly important consideration as potentially more contagious coronavirus variants continue to gain a foothold across the country.
“Until vaccine-induced population immunity is achieved, universal masking is a highly effective means to slow the spread ... when combined with other protective measures, such as physical distancing, avoiding crowds and poorly ventilated indoor spaces and good hand hygiene,” the report states. “Innovative efforts to improve the fit of cloth and medical procedure masks to enhance their performance merit attention.”
Dr. Anthony Fauci, the U.S. government’s top infectious diseases expert, referenced the potential benefits of double masking during a television appearance a few weeks ago, saying: “If you have a physical covering with one layer, you put another layer on it, it just makes common sense that it likely would be more effective.”
During a recent briefing, Los Angeles County Public Health Director Barbara Ferrer also observed that “you’ll see many more people now that are in fact double masking.”
Doing so, she said, was a “practical, sort of thoughtful” way to add “an additional layer between your respiratory droplets and the rest of the world.”
Masks have been effective in slowing the coronavirus’ spread, but there has been debate about whether one-layer cloth masks offer enough protection.
Double masking is not the only way to achieve enhanced protection. The report found that knotting the ear loops and tucking in the extra material of a medical procedure mask provided beefed-up protection as well, and health officials noted that using mask fitter devices “or placing a sleeve made of sheer nylon hosiery material around the neck and pulling it up over either a cloth or medical procedure mask” also could afford additional benefit.
Wearing two masks also isn’t for everyone, as doing so “might impede breathing or obstruct peripheral vision for some wearers,” according to the CDC report.
The recent experiments’ findings also “might not be generalizable to children because of their smaller size or to men with beards and other facial hair, which interfere with fit,” the report stated.
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