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The US Centers for Disease Control and Prevention updated its mask information for the American public on Friday, including clarifying that certain types of masks and respirators offer more protection from the coronavirus than others and offering tips on what consumers should look for when shopping for them.

“Masking is a critical public health tool to prevent the spread of COVID-19, and it is important to remember that any mask is better than no mask,” the CDC said in a statement.

The updated guidelines recommends that Americans wear the most protective mask or respirator they can find that fits well and that they will wear consistently.

“Some masks and respirators offer higher levels of protection than others, and some may be harder to tolerate or wear consistently than others,” the new guidelines say. “It is most important to wear a well-fitted mask or respirator correctly that is comfortable for you and that provides good protection.”

The information was last updated in October. CDC Director Dr. Rochelle Walensky said Wednesday that the agency was planning to update the information to reflect the options that are available to people and the levels of protection different masks provide.

“Loosely woven cloth products provide the least protection, layered finely woven products offer more protection, well-fitting disposable surgical masks and KN95s offer even more protection, and well-fitting (National Institute for Occupational Health and Safety)-approved respirators (including N95s) offer the highest level of protection,” the CDC says.

The updated guidelines note that “a highly protective mask or respirator may be most important for certain higher risk situations, or by some people at increased risk for severe disease.” This includes:

  • When you are caring for someone who has Covid-19
  • When you’re on an airplane or public transportation, especially for a long period
  • When you’re working at a job where you come into contact with a lot of people, especially when not everyone else is masked
  • When you’re not up-to-date on Covid-19 vaccines
  • If you have a risk factor for severe illness like a weakened immune system or a certain medical condition
  • When you’re in a crowded public place, either indoors or outdoors

Masks still aren’t recommended for children under 2, but the CDC “recommends universal indoor masking for all teachers, staff, students, and visitors to K-12 schools, regardless of their vaccination status or the area’s transmission rates.”

The updated guidelines offer tips for getting a better fit and more protection, such as:

  • Wear two masks (a cloth mask on top of a disposable one).
  • Combine a cloth or disposable mask with a fitter or brace.
  • Knot and tuck ear loops of cloth masks where they meet the edge of the mask.
  • Fold and tuck extra material on disposable masks under the edges.
  • Use masks that attach behind the head and neck with elastic bands or ties (rather than ear loops).

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The CDC says consumers looking for masks that meet quality standards can look for certain labels like “meets ASTM F3502” or “meets workplace performance,” and they can go to a National Institute for Occupational Safety and Health website to get more information on personal protective equipment

The agency also says certain respirators don’t meet international standards and has links to sites for more details.

Specially labeled “surgical” N95s “should be reserved for use by healthcare personnel,” the CDC says.

“These updates to our webpage reflect the science on masking, including what we have learned in the past two years,” the agency said in the statement. “We will continue to share the science of masking as it becomes available.”