Masks have become a commodity during the pandemic. There are shortages, they are not easy to find, and even health professionals have been forced to reuse masks intended to be disposable.
What is the best way to disinfect them so that continue to be effective? So that they continue to prevent you from breathing viral particles and from spreading them into the air? 
Below are the pros and cons for several options.
UV (Ultraviolet) Rays
The sun and special lamps give off ultra violet rays. They are a form of energy that is invisible to the human eye. Although they can be damaging to the skin at high levels, they provide us with necessary vitamin D.
The intensity of UV rays depends a lot on geography (meaning where you live), whether you are at sea level or a higher elevation, time of day, season, and other factors.
The color of your skin also affects how you react to UV rays, and for example, if you take certain medication that can cause you to be more sensitive to these rays, such as some antibiotics or birth control pills.
Scientists have begun to joke that the virus doesn’t like heat, precisely because the warmest climates allow UV rays to destroy genetic material of the virus and other microbes.
Robots fitted with UV lamps are commonly used to disinfect water, as well as objects like lab equipment and spaces such as buses and planes.
Though this type of energy has been shown to successfully kill other types of coronavirus, like the one that causes Middle East Respiratory Syndrome (MERS), it still has not been proven to destroy the one causing COVID-19.
What we do know is that it is impossible to prevent by exposing the body directly to these rays to kill the virus. This can be very dangerous for the skin, causing serious injuries, and even cancer.
Experts also say that although UV rays have disinfecting properties, they can also damage the mask material, making it lose its ability to filter germs.
Soap and Water
Though this is the best way to wash your hands and disinfect them, it is not always effective for masks.
This is because, like UV rays, it can damage the fabric of the mask and the elastic that keeps it in place.
In general, N-95 masks, which are used by health professionals, and surgical masks, which are seen most commonly on the streets recently, are manufactured using very fine fibers that come unraveled easily when they come into contact with water and other substances.
Specifically having to scrub and rinse them to remove the soap causes they fibers to fall apart and the fabric of the mask to weaken.
This means that after several washings, a mask is no longer effective.
Alcohol
Spraying masks with alcohol without having to scrub them may seem like a viable option for disinfecting.
However, researchers at the National Institute for Occupational Safety and Health in the United States tested N-95 masks before and after spraying them with alcohol.
After letting them dry overnight, they found that masks sprayed with alcohol stopped 37% less particulates on average than those that were not sprayed.
Best Disinfectant
The Centers for Disease Control and Prevention (CDC) recommends throwing away masks and using a new one, because they are actually intended to be disposable.
However, during the COVID pandemic, this is virtually impossible due to their high cost and shortages.
Consequently, apparently the recommendation which appears to be the most effective at eliminating the virus without damaging the fabric of the mask is to simply hang it up. If possible, outside is best, but just leaving it on a hard surface until the virus dies on its own is recommended.
It’s important to remember that the virus’ survival time is not a universal constant like the speed of light. There are several factors affecting how long they will live:
Viruses live longer at lower temperatures. For example, one study found that the virus died faster at 68° F than at 39° F, and even faster as their exposure to heat increases.
Studies have also found that viruses live much longer on damp materials than dry ones.
It is more probable that the virus will die on mask after removing it and putting it in a dry space. In the United States some hospitals are asking nurses to store their masks in paper bags.
The best way to ensure that the virus is no longer present on the mask is to let it sit for 72 hours.
Regardless, we must remember that we are living in a pandemic, and that scientists and citizens are learning about it together; therefore, there may be changes in what the best practices for cleaning masks in the future are.
Sources: FDA, The National Academies of Sciences, Engineering and Medicine, CDC, NIOS.
