A research team at Kyung Hee University Medical Center has confirmed that wearing the same mask for a long time could worsen bad breath.

The research team, led by Professor Lee Yeon-hee of the Department of Oral Medicine, investigated the saliva and oral microbiological profiles of 50 subjects.

The team divided the patients into two groups -- 25 without bad breath and 25 with bad breath. They usually wore masks for more than three hours.

Professor Lee also collected oral bacteria causing bad breath and measured the presence and quantity of bacterial species by using an RT-PCR (real-time reverse transcription polymerase chain reaction) method.

As a result of the analysis, the team found that methyl mercaptan, a type of volatile sulfur compound, which is one of the main causes of bad breath, was higher in patients with bad breath.

The number was found to be proportional to how long a person wore a single mask, and the increase of methyl mercaptan was due to the major gram-negative anaerobic bacteria among oral microorganisms.

“I started the research based on the hypothesis that bacteria could grow on the inside of the mask and that patients with bad breath may see their symptoms worsen,” Professor Lee said. “For those who wear a mask often and have bad breath, I recommend that they regularly change their mask, brush their teeth, and frequently gargle to improve oral hygiene.”

The research paper was published in the February issue of Scientific Reports.