Updated April 13, 2020
As the world confronts the COVID-19 pandemic, the United States Centers for Disease Control recommends wearing face masks and coverings in public settings to reduce the spread of the life threatening virus.
If you don't have any commercial face masks available, you can make your own from various materials. Because they may be in short supply, it may be a good idea to clean the coverings you have, or at least let them rest for 72 hours between uses.
Cloth Face Masks
Like the rest of your clothes, fabric face coverings can go right in the laundry for a hot wash and dry cycle. The hot, soapy water will disinfect the fabric. If you've been interacting with a person with symptoms, wash your mask thoroughly immediately afterwards, along with your hands, and any clothing you were wearing.
Some medical professionals recommend washing your masks at least once a week. Others suggest more frequent cleaning—as often as every few days or every two uses. Of course, there's nothing wrong with continuing to wash cloth masks as frequently as you can. Ideally, you should have a few on hand so you're never stuck without one.
Cloth masks can actually be quite effective at preventing droplet transmission from the person wearing them, especially when made from thick fabric like quilted cotton.
Standard issue hospital masks with ear loops should be washed or sterilized between every use. If possible, you should avoid relying on such masks for more than eight eight hours of use.
Clean medical masks by rubbing them gently with warm, soapy water, spraying with a bleach solution, or applying a high alcohol sanitizer (over 70%). These masks are a little more gentle—unlikely to hold up to the laundering process.
If you use soap and water, try not to soak the mask, and make sure to rinse all the pieces thoroughly before drying.
N95 and Respirator Masks
High density masks, and those with advanced breathing protection, are highly effective at preventing droplet transmission, but relatively delicate compared to fabric coverings.
N95 masks have an electrostatic charge to help them trap small particles. Alcohol cleaners, or even soapy water, can interfere with this charge, lessening their effectiveness.
Instead, you can steam this more sensitive protective gear in 260 degree Fahrenheit for three minutes, boil it for three minutes, or bake it at 160 degrees Fahrenheit for 30 minutes. If you take the boiling route, try not to interfere too much in the process—moving the mask around while it's in hot water can cause damage.
Safety Note: These and other decontamination methods for N95 masks and respirators have not been approved by the FDA. In this emergency situation they may be used in professional settings, but we don't yet have firm evidence of their effectiveness in a home setting. Using a cloth mask and washing it frequently is the best way to prevent spread from the person wearing the mask to any others.