Unbelievably dirty masks after 12 hours of use
The warm, moist environment inside masks is conducive to the growth of microorganisms. However, not all bacteria are harmful.
Studies have noted that masks worn repeatedly and for long periods of time need to be washed frequently because they harbor bacteria from the skin and respiratory droplets.
Eurofins laboratory found high levels of bacteria and mold in the masks of survey participants. Testing usedface maskDisposable and reusable were worn for 6 and 12 hours for comparison purposes.
The scientists then tested the masks for total bacteria, mold, as well as staphylococcus aureus, which is associated with skin infections, and pyocyanin, which is associated with rashes.
Staphylococcus aureus and Pseudomonas aeruginosa were not found in any of the mask samples. The levels of mold and bacteria were significantly higher in masks worn for 12 hours than in masks worn for 6 hours.
![]() |
Bacterial counts on masks after 6 and 12 hours of use. |
Experts explain that the warm, moist environment in all types of masks is conducive to the growth of microorganisms. But they note that not all microorganisms are harmful.
Professor William Chen - Director of the Food Science and Technology program at Nanyang Technological University (Singapore) said: "There are bacteria in the environment around us, including in the digestive system (mouth and intestines). Therefore, it is not surprising to find bacteria on masks."
Further studies will determine the typebacteriaon masks whether there is any possibility of disease or not.
Dr. Joel Lee - Dean of the School of Chemical and Life Sciences at Nanyang Polytechnic University said that the material of the mask is related to the accumulation of bacteria.
The main difference between disposable and reusable masks, he noted, is the material of the inner layer closest to the mouth.
“This inner layer is most likely where bacteria get trapped when you cough, sneeze, or they can be sprayed into droplets when we talk,” says Dr. Lee.
He also noted that disposable masks have better bacteria filtration and breathability than reusable masks made of cloth.
Traces of bacteria and mold were found in reusable masks worn for 6 hours and not washed for 1 week.
![]() |
Amount of mold on masks after 6 and 12 hours of use. |
Masks that are not washed regularly can collect dust, dirt, sweat and many other types of bacteria, which can cause skin sensitivity, irritation or infection, said Dr. Lee.
Dr. John Chen, from the Yong Loo Lin School of Medicine, National University of Singapore, said that bacteria on masks do not lead to anything serious in the vast majority of cases.
However, some bacteria that live on healthy skin can overgrow on a dirty mask and cause illness. “At low levels, your immune system keeps them in check, but at high levels, they can cause mild to severe allergies, respiratory problems, and even nasal infections,” says Dr. Chen.
Because it is difficult to determine whether there are harmful bacteria on masks, Dr. Chen recommends that people wash their masks regularly or after each use if possible./.