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

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

Scientists have agreed for some time that the main way the virus spreads is by air, not surfaces, and there is growing evidence that small drops of ordinary breathing and speech, which can travel many meters (yards), are a way transmission system.

Added to this is the greater contagiousness of emerging variants, such as B.1.1.7, which takes a lower viral load to cause symptomatic COVID-19 compared to the most common strain.

Adjustment and filtering

At the time when authorities first recommended that people wear facial covers, suitable masks were extremely scarce and the public was encouraged to create improvised solutions with t-shirts or bandanas. But this is far from ideal.

Linsey Marr, a professor of civil and environmental engineering at Virginia Tech, who studies the transmission of disease through the air, told AFP: “The proper functioning of a mask depends on two things: filtering and adjustment.

“Good filtration removes as many particles as possible and a good fit means that there are no leaks on the sides of the mask, where air – and viruses – can leak,” she said, adding that even a small gap can lead to a 50% reduction in performance.

The best materials to block small particles include non-woven polypropylene, which is used to make N95s and many surgical masks, and flat HEPA filters. Among the fabrics, well-woven cotton works best, she added.

Folding

“If you use a fabric mask, choose one that has several layers, preferably one with a pocket in which you can put a good filter material,” said Marr. “Or you can use a double mask using a surgical-type mask with a cloth mask tightened over it.”

Surgical masks are made of a material that filters things well, but they tend to get loose, so the addition of a cloth mask at the top keeps the edges and reduces leakage.

Adding an additional layer improves filtration – if a layer captures 50% of all particles, the combination of two reaches 75%.

But, she added: “We do not recommend using more than two masks. Adding more layers decreases returns and can compromise breathability. Breathing through layers should remain easy; otherwise, air is more likely to leak through the sides of the a mask.”

Masks that have a metal bridge to the nose help ensure a comfortable fit, as do the straps that tighten around the head, not just on the ears. Devices that improve the fit of surgical masks are now available on the market.

“You should feel the mask being sucked in as you inhale, and if you put your hands on the sides of the mask, you should not feel any air leaks as you exhale,” Marr said.

Medical grade respirators

Another option is to obtain N95s or their international equivalents, such as KN95, FFP2 etc.

“They all provide a similar level of filtration, which means protecting particles from entering and leaving,” Ranu Dhillon, global health doctor at Brigham and Women’s Hospital and Harvard Medical School.

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

Furthermore, “there was no joint effort to actually mass produce and distribute these high caliber masks”.

Healthcare professionals have their masks professionally tested every year to ensure they are making the right seal, but Dhillon does not see this as a major obstacle.

“Teaching people to put on a mask, even if not 100 percent perfectly, but more effectively, is 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 definitely helps, but if you are between a person who is breathing and a vent, the virus will still reach you – which makes the masks so crucial, he said.

Milton and Dhillon are cautiously optimistic that their appeals could soon become a 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 scientists studying the flu concluded that it is also transmitted by droplets of ordinary speech and breathing, and that the role of sneezing, coughing and surface transmission was less than previously thought.

His findings were controversial at the time, but COVID-19 renewed interest in research – meaning that masks can be a common sight during flu seasons, long after the pandemic has subsided.

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© 2021 AFP