Study compares how different face masks affect moisture inside the mask – sciencedaily

The study, conducted by researchers at the NIH’s National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), found that face masks significantly increased the humidity of the air the mask wearer breathes. This higher level of humidity in the inhaled air, the researchers suggest, may help explain why wearing masks has been associated with less disease severity in people infected with SARS-CoV-2, because hydration of the respiratory tract is known to benefit the immune system. The study published in the Biophysical Journal.

“We found that face masks greatly increase the humidity of inhaled air and suggest that the resulting airway hydration may be responsible for the documented finding that links the lower severity of COVID-19 disease to wearing of a mask, ”said lead author of the study Adriaan Bax, Ph.D., NIH Research Fellow. “High humidity levels have been shown to mitigate the severity of influenza, and this may be applicable to the severity of COVID-19 through a similar mechanism.

Can high humidity levels limit the spread of a virus to the lungs by promoting mucociliary clearance (MCC), a defense mechanism that eliminates mucus? and potentially harmful particles in the mucus? lungs. High levels of humidity can also strengthen the immune system by producing special proteins called interferons that fight viruses? a process known as the interferon response. Low humidity levels have been shown to impair both MCC and the response to interferon, which may be one of the reasons people are more likely to get respiratory infections in cold weather.

The study tested four common types of masks: an N95 mask, a three-layer disposable surgical mask, a two-layer cotton-polyester mask, and a heavy cotton mask. The researchers measured the humidity level by having a volunteer breathe in a sealed steel box. When the person was not wearing a mask, water vapor from the exhaled breath filled the box, causing the humidity inside the box to rise rapidly.

When the person wore a mask, the moisture build-up inside the box was greatly reduced, as most of the water vapor remaining in the mask condensed and was re-inhaled. To prevent leakage, the masks were fitted tightly against the volunteer face using high density foam rubber. The measurements were taken at three different air temperatures, ranging from approximately 46 to 98 degrees Fahrenheit.

The results showed that all four masks increased the humidity level of the inhaled air, but to varying degrees. At lower temperatures, the wetting effects of all masks increased significantly. At all temperatures, the thick cotton mask led to the highest level of humidity.

“The increased level of humidity is something that most mask wearers have probably experienced without being able to recognize, and without realizing that this humidity might actually be good for them,” Bax said.

Researchers haven’t looked at which masks are most effective against inhaling or spreading the virus and are relying on the CDC for advice on choosing a mask. Previous studies by Bax and his colleagues have shown that any fabric mask can help block the thousands of droplets of saliva that people release through simple speech? droplets which, if released, can remain in the air for several minutes. While the current study did not look at respiratory droplets, it does offer more evidence on why masks are essential in fighting COVID-19.

“Even as more and more people across the country are starting to get vaccinated, we must remain vigilant to do our part to prevent the spread of the coronavirus responsible for COVID-19,” said NIDDK Director Dr Griffin P. Rodgers. “This research confirms the importance of wearing a mask as a simple but effective way to protect those around us and to protect us from respiratory infections, especially during these winter months when susceptibility to these viruses increases.”

The research was supported by the NIDDK Intramural Research Program and the NIH Intramural Antiviral Target Program.