Dr. Robert Wachter, chair of the University of California, San Francisco’s Department of Medicine, agreed. Since omicron is twice as infectious, Wachter wrote, “an encounter that you could have tolerated for delta may well infect you (with) omicron. Knowing this, it’s worth upgrading the protection you get from your mask.”

Here’s the latest advice from the California Department of Public Health ranking the protectiveness of certain kinds of masks:

Best masks

The best masks are N95, KN95 and KF94 masks. Don’t wear an additional face covering on top of these masks.

Better masks

Less effective, but still better than loose cloth masks alone, are surgical masks — commonly called blue masks because there’s usually a blue-tinted color on the outside of the masks.

They can be made more effective by placing a cloth mask over the surgical mask, which makes the fit of the face covering more snug. (Officials don’t recommend wearing two surgical masks.)

“Throw the mask away if it is wet/or dirty or after a day of use, whichever comes first,” the L.A. County Department of Public Health says.

Gaps around the sides of a surgical mask make them less protective than a tighter-fitting mask.

“With gaps, air that has virus particles can easily leak in or out around the sides of the mask. Good fit forces the air that you breathe out and breathe in to go through the mask and be filtered,” the state Department of Public Health says.

Good masks

“Cloth masks can work well if they are tight-fitting and made of materials that filter out small particles,” the state’s website says.

The California Department of Public Health says that good masks have the following properties:

• Two layers of tightly woven cotton with a third layer of non-woven fabric. The third layer could be a mask filter insert or a synthetic fabric such as polypropylene.
• Nose wires to reduce gaps from the nose.
• Adjustable ear loops or straps that go around the head to reduce gaps from the face.

“Face coverings without these properties should not be used in higher-risk situations if other options are available. Examples of less-effective face coverings are two-layer cotton masks, bandanas and gaiters,” the state Department of Public Health says.

Find out more here
https://www.oregonlive.com/coronavirus/2021/12/need-to-upgrade-your-mask-for-omicron-heres-a-ranking-from-good-better-best-to-help-prevent-covid-19.html

SOURCES: PR THAI GOVERNMENT, OREGONLIVE.COM