[Asia Economy Reporter Lee Jung-yoon] The effectiveness of surgical masks and cloth masks varies depending on whether the wearer has coughing symptoms or is infected with the novel coronavirus (COVID-19).
A research team led by Professor Kim Seong-han from the Department of Infectious Diseases at Seoul Asan Medical Center, Professor Kim Min-cheol from the Department of Infectious Diseases at Chung-Ang University Hospital, and Professor Seong Min-gi from the Department of Architectural Engineering at Sejong University released the results on the 7th, confirming the COVID-19 blocking effects of surgical masks and cloth masks.
The study found that for the general public, cloth masks prevent the inflow of the COVID-19 virus from outside, thereby preventing infection. However, in confirmed patients, when coughing while wearing a cloth mask, droplets can escape through gaps and spread the virus, so it is recommended to avoid wearing them if possible.
This study was conducted with the consent of four COVID-19 positive patients in Korea.
The research team divided the patients into three groups: ▲no mask, ▲wearing a surgical mask, and ▲wearing a cloth mask. The patients coughed five times toward a bacterial culture dish (Petri dish) placed about 20 cm away. Afterwards, the amount of virus on the bacterial culture dish and on the inside and outside surfaces of the masks was analyzed.
Analysis showed that the highest amount of virus was found on the bacterial culture dish when coughing without a mask. When wearing surgical or cloth masks, less virus was detected, but a certain amount was still present.
Samples collected from the outside surfaces of surgical and cloth masks after patients coughed tested positive for COVID-19, but most samples from the inside surfaces of the masks were negative.
The research team analyzed that when confirmed patients cough, they expel fine virus particles at high velocity, allowing more virus to pass through the mask than the amount filtered by the mask.
Typically, coughing generates strong pressure that slightly lifts the mask, allowing the virus to escape around the edges. When breathing in, the pressure is lower and the mask is less likely to lift, so the virus is filtered.
Due to these characteristics, viruses from outside are filtered, but when confirmed patients cough while wearing surgical or cloth masks, the virus can still spread.
Accordingly, the researchers recommend that individuals with coughing symptoms or COVID-19 patients wear KF94 masks whenever possible. However, for the general public, wearing cloth masks alone is effective in blocking viruses from entering from outside.
The results of this study were published online on the same day in the Annals of Internal Medicine.
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