Humidity created after wearing face mask prevents Covid-19 spread: Study

Prashasti Awasthi Mumbai | Updated on February 15, 2021

A new study has revealed that humidity created after wearing face masks helps in mitigating the spread of the coronavirus. This also hydrates the respiratory tract and boosts the immune system.

The study, published in the Biophysical Journal, stated that the higher level of humidity in inhaled air could be linked to lower levels of Covid-19 severity.

The study’s lead author, Adriaan Bax from the US NIH’s National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) said: “We found that face masks strongly increase the humidity in the inhaled air and propose that the resulting hydration of the respiratory tract could be responsible for the documented finding that links lower Covid-19 disease severity to wearing a mask.”

Also read: Covid-19: ‘Proper fit’ of face mask more crucial than material, says study

He added, “High levels of humidity have been shown to mitigate the severity of the flu, and it may be applicable to the severity of COVID-19 through a similar mechanism.”

The authors of the study noted that high levels of humidity can limit the spread of a virus to the lungs by promoting mucociliary clearance (MCC). MCC is a defense mechanism that removes mucus and potentially harmful particles in the lungs.

This can further help in producing special proteins called interferons due to higher levels of immunity.


For the study, the researchers examined four common types of masks — N95 mask, a three-ply disposable surgical mask, a two-ply cotton-polyester mask, and a heavy cotton mask.

They asked the volunteers to exhaled into a sealed steel box to measure the level of humidity.

When the person wore no mask, the water vapor of the exhaled breath filled the box, leading to a rapid increase in humidity inside the box, the study noted.

Also read: Covid-19 disposable face masks could be recycled to make roads: Study

However, when the person wore a mask, the buildup of humidity inside the box plummeted significantly, due to most of the water vapor remaining in the mask, becoming condensed, and being re-inhaled.

The scientists took measurements at three different air temperatures, ranging from about 46 to 98 degrees Fahrenheit.


The findings of the study observed that all four masks increased the level of humidity of inhaled air but to varying degrees.

The researchers noted that at lower temperatures, the humidifying effects of all masks rose sharply while thick cotton masks led to the most increased level of humidity at all conditions.

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

Published on February 15, 2021

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