The US Centers for Disease Control and Prevention have updated their guidance for face masks, saying they protect the wearer from getting Covid-19 rather than just others from asymptomatic carriers, as previously thought.
For the better part of 2020, the CDC was encouraging mask use to protect the community from “asymptomatic or presymptomatic infected wearers who feel well and may be unaware of their infectiousness to others,” who they estimated were responsible for more than 50 percent of transmissions.
In guidelines updated late on Tuesday, however, the CDC now says that masks “also help reduce inhalation” of droplets by the wearer.
The CDC now says that studies have demonstrated that cloth masks help reduce wearers’ exposure by filtering droplets and particles smaller than 10 microns, though effectiveness varies based on the material, thickness and number of layers. Polypropylene may enhance effectiveness by generating a static electricity charge that enhances capture, while silk may repel droplets, to list but two examples they mention.
“Multiple layers of cloth with higher thread counts” can filter nearly 50 percent of fine particles measuring less than 1 micron, the CDC said.
Mask mandates and lockdowns have been imposed around the world to curb the spread of the respiratory virus, which was first reported in China last December and became a pandemic in March. Nearly 52 million people across the globe have tested positive for the virus so far, while 1,28 million deaths have been attributed to it.
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