Oct 19, 2021

Mawazo Writing Africa

Writing about the main

Avoid double masking with surgical mask, says CDC

Double masking is wearing one mask on top of another. It helps improve the fit and filtration of your mask.

According to recently provided guidance on masking based on two experiments, scientists found that wearing a cloth mask over a medical procedure mask was shown to substantially improve protection against exposure and transmission of the virus by about 95 per cent.

The guidelines instructed that the outer cloth mask should push the edges of the surgical mask against your face and fit well on the face, preventing exposure to aerosols made by coughing and breathing.

However, the study discourages the doubling of surgical mask over surgical mask, cloth on cloth or surgical mask over an N95 mask.

“Don’t double surgical masks…because of their loose-fitting nature, surgical masks should never be layered. Adding a second one may actually make the fit worse and it might compromise your breathing,” said the study.

Restricting airflow

It also instructed that KN95 mask should not be layered with any other mask since this is likely to restrict airflow too much.

“If the mask is overly restrictive, it may cause skin irritation or develop air leaks on the side. Overly restricting your airflow may have consequences on the effectiveness of the mask,” states the study.

The first experiment assessed how effectively various mask combinations reduced the amount of particles emitted during a cough in terms of collection efficiency.

The effectiveness of the following mask configurations to block these aerosols was assessed: a three-ply medical procedure mask alone, a three-ply cloth cotton mask alone, and the three-ply cloth mask covering the three-ply medical procedure mask (double masking).

The second experiment assessed how effectively the two modifications to medical procedure masks reduced exposure to aerosols emitted during a period of breathing.

Virus transmission

Ten mask combinations, using various configurations of no mask, double masks, and unknotted or knotted and tucked medical procedure masks, were assessed, including source with no mask and receiver with double mask or source with double mask and receiver with no mask.

A modified simulator with two pliable elastomeric head forms (a source and a receiver) was used to simulate the receiver’s exposure to aerosols produced by the source.

Results from the first experiment demonstrated that the unknotted medical procedure mask alone blocked 56 per cent of the particles from a simulated cough and the cloth mask alone blocked 51 per cent of the particles.

The combination of the cloth mask covering the medical procedure mask (double mask) blocked 85 per cent of the cough particles.

In the second experiment, adding a cloth mask over a medical procedure mask reduced the cumulative exposure of the unmasked receiver by 82 per cent. When the source and receiver were both fitted with double masks, the cumulative exposure of the receiver was reduced 96 per cent.

“Controlling virus transmission is critical, not only to reduce the widespread effects of the Covid-19 pandemic on human health and the economy, but also to slow viral evolution and the emergence of variants that could alter transmission dynamics or affect the usefulness of diagnostics and vaccines,” says the study.