Masks are the single most effective way to protect yourself and others from getting infected with the coronavirus that causes Covid-19, the disease.
Masks are required on public transportation and in airports and transit stations.
What type of mask should you wear?
N95 masks are the gold standard of masks because they block 95% of large and small particles using an electrostatic filter.
If everyone would wear N95 masks for four weeks in risky settings, "it would stop the epidemic," Dr. Abraar Karan, an internal medicine physician at Brigham and Women's Hospital and Harvard Medical School, told CNN Chief Medical Correspondent Dr. Sanjay Gupta.
Beware of fake N95 masks -- they have flooded the market, and they may not meet safety standards. Look for the National Institute for Occupational Safety and Health's NIOSH stamp of approval.
Should you wear two masks?
The CDC on Wednesday updated its guidance to suggest wearing a cloth mask over a disposable mask, such as one of those blue surgical masks, as a way to add more protection.
In fact, new data from the CDC shows that layering a cloth mask over a disposable medical mask can block 92.5% of potentially infectious particles from escaping by creating a tighter fit and eliminating leakage.
Fauci, director of the National Institute of Allergy and Infectious diseases, recently has been sporting two masks, one on top of the other.
The CDC advised people not to wear two disposable masks, however.
"Disposable masks are not designed to fit tightly and wearing more than one will not improve fit," the CDC said in its updated guidance.
You also should not wear any mask over a KN95 mask, the CDC said.
"We continue to recommend that masks should have two or more layers, completely cover your nose and mouth, and fit snugly against your nose and the sides of your face," Walensky said at a White House briefing Wednesday.
If you want to know more about this topic, we invite you to read the article: What you need to know about face masks as protection against coronavirus
What you need to know about face masks as protection against coronavirus-CNN health, February 10, 2021