CDC study: 2 masks and tighter fit could reduce COVID-19 exposure by up to 96%

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Posted at 11:17 AM, Feb 10, 2021

Masks and facial coverings are required in most settings to slow the spread of the coronavirus. The CDC released new data Wednesday on how to improve mask fit that reduces a person’s exposure to the virus by as much as 96%.

It comes down to reducing gaps, by double masking, nose wires, and knotting ear loops and tucking in the sides.

The CDC’s study looked at what impact, if any, these simple methods had on slowing the spread.

Coronavirus is spread from person-to-person through droplets in the air when an infected person speaks, coughs, sings, yells, breaths, etc. and those droplets are inhaled by others near them.

Wearing a mask has been a recommended precaution for almost the entire pandemic to help slow the spread of the virus by reducing the amount of droplets released by an infected person and protecting a person from inhaling droplets.

Double masking

The CDC study looked at the impact wearing two masks had on reducing exposure to aerosols, or droplets in the air. They looked at the difference between wearing a three-layer cotton cloth mask or three-layer medical procedure mask alone, and then the effectiveness of wearing the cloth mask over the medical procedure mask.

They found the better fit, and reduced gaps, achieved by wearing the two mask types, specifically a cloth mask over a medical procedure mask, greatly reduced a wearer’s exposure.

The cloth mask alone blocked about 44% of aerosols in the study, the medical procedure mask blocked about 42%. The two of them worn together blocked about 92% of the simulated cough particles, and reduced a wearer's exposure by about 83%.

Overall, if two people are both wearing double masks, they reduce their possible exposure to aerosols by more than 96%.

Knotted and tucked

The researchers then looked at the benefits of different modifications that aimed to get the sides of the mask closer to the face, reducing gaps near the ears and cheeks.

They found by knotting the ear loops for a tighter fit and tucking in the sides of the medical procedure mask, it reduced exposure to aerosols by more than 60% if one person is wearing a mask and one person is not. That jumps to nearly 96% reduction in exposure if both people are wearing a knotted and tucked mask.

“A knotted and tucked medical procedure mask is created by bringing together the corners and ear loops on each side, knotting the ears loops together where they attach to the mask, and then tucking in and flattening the resulting extra mask material to minimize the side gaps,” the report states.

The CDC also recommends using a moldable nose wire or other “fitter” device that keeps the mask close to the bridge of the nose and reduces gaps.

Although there are millions of people getting the COVID-19 vaccine, there are still millions more who have not gotten it; and even those who have the vaccine can still possibly spread the coronavirus. The CDC and health experts agree that practicing safety measures will continue for a while to slow the spread and control the transmission of the coronavirus and any variants.

“Until vaccine-induced population immunity is achieved, universal masking is a highly effective means to slow the spread of SARS-CoV-2 (coronavirus) when combined with other protective measures, such as physical distancing, avoiding crowds and poorly ventilated indoor spaces, and good hand hygiene,” the CDC report concludes.

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