As Covid-19 cases surge in the U.S. due to the spread of the highly transmissible omicron variant, experts are urging the public to upgrade their masks in addition to receiving booster shots and getting tested, but which masks offer the best protection against the virus?

An employee arranges N95 face masks in a box, at a factory that produces 40,000 N95 masks per day, ... [+] in Mexico City on May 21, 2020. (Photo by ALFREDO ESTRELLA/AFP via Getty Images)

Health officials warn against wearing a single reusable cloth mask to protect against the omicron variant, as tiny droplets can still make it through large pores of fabric.

Experts recommend wearing a tight-fitting mask with efficient filtration like an N95, KN95 or KF94 mask, which can filter out at least 95% of airborne particles, according to the Centers for Disease Control and Prevention.

The difference between the three masks comes down to which country or organization certified the mask—the U.S. National Institute of Occupational Safety and Health certifies N95 masks, while KN95 masks are manufactured in China and meet Chinese standards and KF94 masks meet Korean standard requirements.

If N95, KN95 or KF94 masks are difficult to find, experts say double masking, specifically a surgical mask with a cloth mask on top, can provide better protection than just a single cloth mask.

N95, KN95 and KF94 masks can be reused, as long as they don’t have bodily fluids on them, broken straps or a broken nose piece, according to the CDC.

To clean these types of masks, place the mask into a paper bag at room temperature for at least three to four days, or heat the mask at 158 degrees Fahrenheit for one hour—both of which are effective at allowing virus particles to die off—according to a study published in the Journal of Emergency Medicine.

“Cloth masks are little more than facial decorations. There's no place for them in light of Omicron,” Dr. Leana Wen, an emergency physician and visiting professor of health policy and management at the George Washington University Milken Institute School of Public Health, told CNN. “We need to be wearing at least a three-ply surgical mask. You can wear a cloth mask on top of that, but do not just wear a cloth mask alone.”

The size of a particle of the novel coronavirus is about 0.12 micrometers. A study published in PeerJ found the pore size of 20 cloth masks ranged from 80 to 500 micrometers, underscoring health experts’ urging to wear a mask that has higher standards for filtration.

668,497. That’s the seven-day average of new cases reported in the U.S. as of Friday, according to the CDC.

Officials have sounded the alarm to wear higher-quality masks as the omicron variant causes the highest levels of cases ever reported during the pandemic in the U.S. Hospitalizations are also on the rise in the country, with 141,385 people hospitalized—up from about 103,000 hospitalizations last Monday, according to the Department of Health and Human Services. Children are also being admitted to the hospital in record numbers amid the surge of cases, according to the CDC. At least 18 states reported a critical shortage of hospital workers over the weekend as the number of cases began to overwhelm some hospital systems.

Why N95, KN95 masks are so much more effective than cloth (USA Today)

These 18 States Are Grappling With Critical Hospital Worker Shortages As Covid Hospitalizations Surge (Forbes)

Mask Wearing Linked To 53% Cut In New Covid-19 Cases—It's The Best Public Health Measure Against The Virus, Study Finds (Forbes)

Here's Who's Still Wearing Masks The Most (And Least) (Forbes)