It’s time to wear a better mask, say experts

© Alex Edelman
Anne Arundel County Fire Department firefighter in Maryland tests his N-95 mask

As new, more transmissible variants of the coronavirus spread, experts say it’s time to consider using a medical-grade respirator or wearing a surgical mask and a cloth mask together.

Scientists have agreed for some time that the primary way the virus is spread is through air, rather than surfaces, and it is increasingly evident that small droplets from ordinary breathing and speaking can travel several meters (yards) is a common transmission method.

© Maryam EL HAMOUCHI
Comparison of the different ways to wear masks to maximize protection against the coronavirus.

Added to this is the greater contagiousness of emerging variants, like B.1.1.7, which require a smaller viral load to cause symptomatic Covid-19 compared to the more common strain.

– Adjustment and filtration –

Back in the days when authorities first recommended people to wear headgear, suitable masks were extremely rare, and the public was encouraged to create makeshift solutions out of t-shirts or bandanas. But these are far from ideal.

Linsey Marr, professor of civil and environmental engineering at Virginia Tech, who studies the transmission of airborne diseases, told AFP: “The proper functioning of a mask depends on two things: filtration and fit.

“Good filtration removes as many particles as possible, and a good fit means that there are no leaks on the sides of your mask, where air – and viruses – can escape,” he said. she said, adding even a small space could result in a 50 percent reduction in performance.

The best materials for blocking small particles include non-woven polypropylene, which is used to make N95s and many surgical-type masks, and HEPA filters in airplanes. Among fabrics, tightly woven cotton works best, she added.

– Double –

“If you wear a cloth mask, choose one that has multiple layers, ideally one with a pocket that you can slip good filter material into,” Marr said. “Or you can double the mask by wearing a surgical-type mask with a tight-fitting fabric mask over it.”

Surgical masks are made of a material that filters things well, but they tend to be loose, so the addition of a fabric mask on top maintains edges and reduces leakage.

Adding an extra layer improves filtration – if one layer traps 50% of all particles, the combination of the two reaches 75%.

But, she added: “We don’t recommend wearing more than two masks. Adding extra layers proves diminishing returns and can compromise breathability. It must remain easy to breathe through the layers; otherwise, air is more likely to leak from the sides of the mask. “

Masks with a metal nose bridge ensure a snug fit, as do the straps that tighten around the head, not just the ears. Braces that improve the fit of surgical masks are now available on the market.

“You should feel the mask suck inward as you breathe in, and if you hold your hands on the sides of the mask, you shouldn’t feel the air escape as you breathe out,” Marr said.

– Medical grade respirators –

Another option is to get N95, or their international equivalents such as KN95, FFP2, etc.

“They all provide a similar level of filtration, meaning protection against particles entering and leaving,” said Ranu Dhillon, general practitioner at Brigham and Women’s Hospital and Harvard Medical School.

Dhillon, who has been pushing for better masks since last spring, is frustrated by the lack of a clear message to the public about the value of better masks.

Further, “there was no concerted pressure to mass produce and distribute these higher caliber masks.”

Healthcare workers have their masks professionally tested every year to make sure they’re making the right seal, but Dhillon doesn’t see this as a major obstacle.

“Teaching people how to fit a mask, even if it’s not 100% perfectly, but more effectively, is something very doable.

– Masks in our future? –

The key to conceptualizing the threat is to think about cigarette smoke, said Donald Milton, professor of environmental health at the University of Maryland.

Ventilation certainly helps, but if you’re between a breathing person and an exhaust duct, the virus will always get to you – which makes the right masks so crucial, he said.

Milton and Dhillon are cautiously optimistic that their calls may soon become policy under President Joe Biden’s administration, and CNN reported last week that the U.S. government was working on the first official mask standards.

Before the pandemic, Milton and other aerosol scientists who study influenza concluded that it was also transmitted by tiny droplets from ordinary speech and breathing, and that the role of sneezing, coughing and transmission through surfaces was smaller than expected.

Their findings sparked controversy at the time, but Covid-19 renewed its interest in research – which means masks could be commonplace during difficult flu seasons, long after the pandemic has subsided.

ia / ec