DIY masks may not protect you from COVID-19. But here's why it's smart to wear one

Following the Centers for Disease Control and Prevention's new recommendation that Americans wear cloth face masks in public, especially in areas with significant COVID-19 spread, many are asking which materials offer the best protection against the virus.

Americans can use "cloth face coverings fashioned from household items or made at home from common materials at low cost," the CDC website says.

Dr. William Schaffner, medical director for the National Foundation for Infectious Diseases, said it's easy to get "hung up on the materials."

"The concept is to get something in front of your face, even if you're tying a bandana in front of your nose and mouth," he told ABC News.

Masks work in two ways, Schaffner explained.

They prevent particles from exiting the mask wear's nose and mouth but masks also prevent outside particles from getting inside the wear's nose and mouth. Still, the data to support wearing cloth masks to keep particles out, and thus stop the mask wearer from getting sick, is thin, he said.

In other words, wearing a cloth mask probably won't protect you. But that doesn't mean you should ignore the CDC's recommendation to wear one.

"The utility of a mask to inhibit what's going out is pretty good," Schaffner said.

There's mounting evidence that a significant number of individuals who contract the virus may spread it before developing symptoms, or may be asymptomatic.

"This means that the virus can spread between people interacting in close proximity -- for example, speaking, coughing, or sneezing -- even if those people are not exhibiting symptoms," the CDC notes. "In light of this new evidence, CDC recommends wearing cloth face coverings in public settings where other social distancing measures are difficult to maintain."

While the personal protective benefit of wearing a mask may be low, the benefit to society at large is real.

"You can protect those around you by wearing a mask and they will protect you," Schaffner said. "If we all do that, it makes it more difficult for the virus to move from one person to another."

The new recommendations do not mean that Americans can relax other public health measures, such as social distancing. Instead, they should wear facial protection while continuing to keep at least six feet between themselves and others, while also remaining at home whenever possible.

What to know about Coronavirus:

• How it started and how to protect yourself: Coronavirus explained
• What to do if you have symptoms: Coronavirus symptoms
• Tracking the spread in the US and Worldwide: Coronavirus map

Americans also "shouldn't go out and buy masks that otherwise should be used in health care settings," Schaffner noted. While N95 masks are more effective at keeping particles out and better protect the mask wearer, they are in short supply and should be reserved for health care workers and first responders, according to the CDC.

For more information on how to make a cloth mask, see the CDC's mask-making tutorial.