últimas notícias

Masks have proved to be dramatically effective in slowing the spread of the coronavirus. But is a cloth mask enough? Should we be wearing two masks? And how about the medical-grade N95 face coverings?

Though transmission of the virus has slowed markedly in Los Angeles County, the risk of spreading the disease remains high — and the presence of new, potentially more contagious variants only heightens the danger.

There has been some debate about whether cloth masks offer enough protection. Experts say they are definitely better than not wearing a mask at all, but there may be better options.

The U.S. Centers for Disease Control and Prevention recently recommended that people wear masks with two or more layers of breathable fabric.

If wearing a cloth mask, the CDC says to look for these qualities:

• Tightly woven fabrics, such as cotton and cotton blends
• Breathable material
• Two or three fabric layers

Less effective types of masks are:

• Made of loosely woven fabrics, such as a loose knit
• Made of material that’s difficult to breathe through (like plastic or leather)
• Those with a single layer

Avoid these:

• Masks that are made of fabric that makes it hard to breathe, such as vinyl
• Masks with exhalation valves or vents, which allow virus particles to escape

Wearing two masks is becoming a more widespread practice.

Los Angeles County Public Health Director Barbara Ferrer observed during a briefing Wednesday that “you’ll see many more people now that are in fact double masking.”

She said it was “practical, sort of thoughtful” to add “an additional layer between your respiratory droplets and the rest of the world.”

One way to double mask is to put on a medical-grade mask first and then cover that with a cloth face covering, Ferrer said.

During an appearance on the “Today” show this week, Dr. Anthony Fauci, the nation’s top infectious disease expert, said: “If you have a physical covering with one layer, you put another layer on it, it just makes common sense that it likely would be more effective.

“That’s the reason,” he said, “you see people either double masking or doing a version of an N95.”

An L.A. County scientific advisory group is examining the data surrounding whether double masking is effective, and in what settings.

KN95 versus N95

Another option is the KN95 mask, which is medical grade but manufactured to a Chinese specification. They are probably more effective than cloth face coverings, Ferrer said.

One advantage of KN95 masks is that they may be easier to use for the public than the gold-standard respiratory mask used by medical professionals in the U.S., the N95 mask.

Although N95 masks are very effective, they need to be specially fitted to the wearer to maximize their effectiveness, Ferrer said.

Also, a run on N95 masks could cause supply shortages for health professionals. Ferrer said the county’s scientific advisory group needed to review guidelines by government occupational safety and health experts on masks and other emerging science.

“I would caution people on letting us complete our review of the literature, the studies, and what OSHA is saying about this,” Ferrer said, referring to the Occupational Safety and Health Administration.

Ferrer emphasized, however, that Angelenos needed to follow public health guidance already in place regarding the wearing of masks.

With vaccines still in short supply, she said, taking personal steps to tamp down transmission is the surest way to improve conditions to the point that the county can reopen additional businesses and allow more students to return to the classroom.

“If you care about our children, if you care about our small businesses,” she said, “we need you to follow the public health directives all of the time.

“Just because some sectors have reopened doesn’t mean the risk of transmission has gone away. It hasn’t.”

Vaccines

Even getting both required doses of the existing vaccines doesn’t mean you should stop wearing a face covering or following other infection-prevention protocols, according to the CDC.

“Not enough information is currently available to say if or when CDC will stop recommending that people wear masks and avoid close contact with others to help prevent the spread of the virus that causes COVID-19,” the agency wrote on its website.

Getting both doses of the currently available vaccines, while extremely effective at protecting you from illness, may not prevent you from becoming an asymptomatic carrier of the virus and infecting other people with it, officials say. Further study is needed to ascertain that.