How You Can Disinfect Your Mask for Reuse During the COVID-19 Pandemic, As Told By A Medical Professor

As the CCP virus cases in Singapore escalate quickly, Prime Minister Lee Hsien Loong has announced to extend the circuit breaker period by four weeks to June 1. The partial lockdown has started since April 7 and most workplaces and schools have been closed since then. Only key economic sectors and essential services – such as food establishments, markets and supermarkets, clinics, hospitals, utilities, transport and key banking services remaining open.

In cases of insufficient surgical masks in the market due to panic buying, a Taiwanese professor has found a brilliant method to disinfect reused surgical masks at home — dry steaming with a rice cooker. 

During a light-hearted presentation on Sunday (5 April), Taiwan’s Food and Drug Administration (FDA) Director-General Wu Shou-mei showed Central Epidemic Command Center (CECC) head Chen Shih-chung how to disinfect a mask using a rice cooker. Credit: YoutubeSource: Youtube

An experiment carried by Chung Shan Medical University Department of Occupational Safety and Health associate professor Lai Chane-yu (賴全裕) and his team has concluded that dry steaming a surgical face mask with a common rice cooker for three minutes is able to achieve a sterilization rate of 99.7%. However, this method would reduce the mask’s filter quality by 10%. Thus, he suggests practising such measures only when masks are in short supply or during an emergency.

A man in Thailand decided to try this method after watching Taiwan’s Digital Minister, Audrey Tang, successfully disinfect her mask. Unfortunately, it did not turn out too well.

Thai Man attempts to disinfect his masks using the rice cooker.(Credit: mai.sukadecha.7 @Facebook)

 

Mask melted in the rice cooker. (Credit: mai.sukadecha.7 @Facebook)

 

Instructions for disinfecting surgical masks using rice cooker by Osh RPETesting Center Fit Factor Training Center. (Credit: OshRPETestingCenterFitFactorTrainingCenter@ Facebook)

The inner wall of rice cookers can reach 145 to 170 degrees Celsius. If placed directly over the metal element at the bottom of the cooker, the high temperature will cause the mask to shrink or melt. Thus, a metal pot must be placed inside the cooker on top of the metal rack to shield the mask from the cooker’s sides, Lai suggested.

In order to achieve the optimal sterilization effect, Lai recommends leaving the mask inside for another five minutes after the three-minute heating cycle has completed. It is recommended to wash the rice cooker after dry steaming the mask before using it for cooking purposes later on.

Due to Lai’s explanation, a newly certified surgical mask usually only has an 80% filtering effectiveness rate. However, the mask can be sterilized up to five times and still have a 70% filtering effectiveness rate remaining through this method, thus suggesting that such life hack is feasible.

With internet rumours saying that hairdryers can be used as an alternative circulating around, Lai responded that although he has not yet experimented on it, he does not recommend such a method as the sterilization effect through hair dryer may not be even. As for spraying surgical masks with alcohol or bleach, Lai stated that it is a bad idea as well since it can damage the material of the mask and reduce the capability of the filter by 50%.

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