COVID-19 precautions: Face masks can protect you from aerosol infections, but only if sterilised the right way
Unsterilised masks may act as a contaminated object and spread infection instead of protecting you from it.
Face masks are a part of the new normal that the COVID-19 pandemic has brought about in our lives. Well-fitted masks can protect you from droplet transmission when someone sneezes or coughs (or even talks for long) near you. However, due to the heavy demand for masks, most experts recommend using reusable face masks to conserve supply and ensure that those who need them the most continue to have access to them.
Surgical masks are said to be the best suited for the situation but it is best to not reuse them. Other masks like N95 masks and three-layer face covers can be sterilised and reused.
Unfortunately, not a lot of people know the right way to sterilise masks for reuse. Unsterilised masks may act as a contaminated object and spread infection instead of protecting you from it. Even when people do attempt to sterilise, they are often unaware that not every sterilization technique works as good for every type of mask.
The Government of India recently warned people against using N95 masks that have a valved respirator. This is because this type of mask can keep aerosols from coming in but they are not effective in stopping the spread of virus outside the mask. Also, these masks are not effective in stopping small virus particles.
Washing, drying in sunlight and ironing
Washing is one of the easiest ways to clean a face mask. However, just any kind of washing won’t really do and you can’t just dry the mask inside your house as you would dry clothes on a rainy day. Some experts even suggest that soap and water can reduce the efficiency of N95 masks.
The Centers for Disease Control and Prevention, USA suggests that while washing a face mask you should use the warmest possible water, as per the cloth of the mask, though any detergent would work. If you are washing with your hands, then soak the mask in five tablespoons of household bleach per 3.78 litres (one gallon) of water at room temperature. Make sure the bleach is not ‘colour-safe’ as it would not be as effective then.
Always dry the mask in the open air under direct sunlight for five hours or with the warmest possible dryer setting in the machine. The Union Ministry of Health and Family Welfare suggests ironing face covers for about five minutes before use. Ironing is a method of dry heat sterilisation.
Since heating is believed to kill microbes, microwaving is being considered as a possible way to sterilise masks. However, there are a lot of concerns when it comes to sterilisation using microwaves. For one, the metal pieces on masks can catch fire inside a microwave or melt some parts of the mask.
In a recent study, a group of researchers stated that N95 masks can be effectively sterilised in a microwave oven for up to 20 cycles without having either of the side effects.
The method they used was: Cover a glass of water (60 mL of water) with a mesh (the ones that are used to wrap commercial products) and secure the mesh with a rubber band. Then, put the mask over the glass and microwave it all for three minutes. The steam rising from the water is what sterilises the mask here.
Since this is still new territory, you could play it safe by boiling face covers in a salt solution for five minutes. As per the health ministry, this can ideally be done in a pressure cooker -- pressure boil the mask for 10 minutes and let it dry, or boil it in another utensil for 15 minutes if that isn’t available.
Spraying hand sanitizer
Hand sanitisers contain alcohol and are hence considered to be effective in sterilising hands. However, when it comes to masks, it is best to stay away from alcohol. It is suggested that alcohol damages N95 masks and reduces their efficiency. There isn’t much data on the effect of alcohol on face covers yet so best avoid that as well.
UV radiation is one of the standard ways to sterilise equipment and surfaces. They kill microbes by degrading various proteins and the genetic material of the microbes. According to a study from April 2020, 15 minutes of UVC radiation is enough to kill SARS-CoV-2, the causative agent of COVID-19 .
A study done in the USA indicated that N95 respirators can withstand up to 10 cycles of UV radiation. However, the procedure affects the integrity of the mask material eventually.
Over the last few months, many new portable UV disinfection boxes have come into the market for regular use. It is important to confirm the legitimacy of these products before you make a purchase.
For more information, read our article on How to make face cover at home.
Health articles in Firstpost are written by myUpchar.com, India’s first and biggest resource for verified medical information. At myUpchar, researchers and journalists work with doctors to bring you information on all things health.
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