Rice cooker can be used to sterilize masks: Taiwanese study

Taiwanese professor finds rice cookers can be used to sterilize surgical face masks

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Face mask being placed in rice cooker. 

Face mask being placed in rice cooker.  (CNA photo)

TAIPEI (Taiwan News) — As panic buying of surgical face masks due to the Wuhan virus continues to grip Taiwan, a Taiwanese professor has found that "dry steaming" a mask in a rice cooker can sterilize it for reuse.

A study led by Chung Shan Medical University Department of Occupational Safety and Health associate professor Lai Chane-yu (賴全裕) and his team found that a common rice cooker can "dry steam" a surgical face mask and achieve a sterilization effect. However, Lai emphasized the method reduces the mask's filter quality and that such a method should only be used when masks are in short supply during an emergency.

In a Facebook post on Tuesday (Feb. 11), Lai said it was found that heating a face mask in a rice cooker for three minutes can achieve a sterilization rate of 99.7 percent. He said that although this would diminish the mask's filter quality by 10 percent, it could be a stop-gap measure to provide some protection during the Wuhan coronavirus outbreak.

However, many netizens who tried the method reported their mask shrank or melted. Lai explained the inner wall of rice cookers can reach 145 to 170 degrees Celsius and a metal pot must be placed inside the cooker to shield the mask from the cooker's sides.


Mask melts when placed directly on bottom element. (Instagram meme)

Lai said that placing the mask over the metal element at the bottom of the cooker could also lead to its destruction due to high temperatures at the base of the device. To shield the mask, he suggested inserting the metal pot on top of the metal rack inside the cooker.

After the cooker has completed its three-minute heating cycle, he recommends leaving the mask inside for another five minutes to achieve the optimal sterilization effect. Lai said that certified surgical masks when new usually only have a filtering effectiveness rate of 80 percent, but with this method, the masks can be sterilized up to five times and still achieve a filtering effectiveness rate of 70 percent.

As for spraying the masks with alcohol or bleach, can damage their material and weaken their filtration capabilities. Lai said that spraying a surgical mask just once with alcohol or bleach can reduce its filtering capabilities by 50 percent, reported UDN.

In response to internet rumors that masks can be sterilized with hairdryers, Lai said that this method has not yet been tested. He said he does not recommend it because the sterilization effect achieved through using a hairdryer may be uneven.


Mask shrivels after being placed inside a bowl. (Facebook screenshot)