Humidity from Mask Wearing May Lessen Respiratory Disease Severity

different types of protective face mask against blue background
Study investigators tested N95, 3-ply disposable surgical, 2-ply cotton-polyester, and heavy cotton masks to assess humidity levels and corresponding benefits.

Humidity from wearing masks could aid in protecting wearers from respiratory diseases, including COVID-19, according to a study led by researchers from the National Institutes of Health.

Study investigators tested 4 common types of masks, N95, 3-ply disposable surgical, 2-ply cotton-polyester, and heavy cotton. The masks were tightly fitted on the face of a volunteer who breathed into a sealed steel box to measure humidity levels. Humidity level measurements were recorded at 3 different air temperatures, ranging from 46 to 98° F.

Researchers found all tested mask types increased humidity levels of inhaled air to varying degrees. The heavy cotton mask resulted in the most increased humidity level at all temperatures. Additionally, the humidifying effects greatly increased for all masks at lower temperatures.

These results suggest that in addition to providing a barrier that reduces the spread of droplet and aerosols, masks provide an additional benefit associated with decreasing severity of respiratory diseases. Increased humidity within masks may hydrate the respiratory tract to benefit the wearer’s immune system via 2 possible approaches. Firstly, high humidity levels can limit the viral spread to the lungs via promoting the mucociliary clearance defense mechanism. Secondly, increased humidity strengthens the immune system by producing interferons to combat viruses.

However, this study did not examine the effectiveness of masks against inhalation or transmission of the virus. Regardless, the findings support the necessity of wearing masks to fight against COVID-19. “Even as more people nationwide begin to get vaccinated, we must remain vigilant about doing our part to prevent the spread of coronavirus that causes COVID-19,” the researchers concluded.


Researchers propose that humidity from masks may lessen severity of COVID-19. National Institutes of Health. Published on February 12, 2021. Accessed March 8, 2021.

This article originally appeared on Infectious Disease Advisor