Saturday, July 25, 2020

Masking Up Minnesota--For One For All

Environmental & Science Education
Edward Hessler

Minnesota Masks

As you know Minnesota Governor Tim Walz announced a statewide masking mandate on July 22 to take effect July 25. The rule applies to most indoor spaces except in people's homes and to outdoor spaces where physical/social distancing cannot be maintained. For full details on requirements, exceptions, etc., see here.

Masks: Difference Makers

On July 23 NPR correspondent Nurith Aizenman whose beat includes global health and international development, reviews the latest science (evidence) and includes a graphic which I urge you to look at. It shows what happens over seven five-day cycles when masks reduce transmission by 30%. Masks make a difference. The impact adds up cycle after cycle of infections. She writes "Essentially, instead of exponential growth you've triggered what's called exponential decay."

Aizenman's reporting includes comments from Ashish Jha, the Director of the Harvard Global Health Institute. I include some of this below, including direct quotes from Jha and Aizenman's original reporting but emphasize that it doesn't fully summarize the story.

"'I think if you're wearing masks, you probably can get some number of people back into offices. You probably can't go back to the original level of office occupancy. But you can start getting some people back in, especially if you can improve ventilation.' The same applies to nonessential retail businesses and even, he says, schools--especially middle and high schools, where not just teachers but students could likely wear masks.

Finally, this statement by Jha puts the power of masking into sharp perspective.. "'There is no single thing that gets us every thing we want, but universal masking is a really critical part of letting us get, like 80% of our lives back.'" (my emphasis)

Hand-washing, maintaining social-/physical distancing AND mask-wearing (covering mouth AND nose) are proven COVID-19 interventions. Assiduously practiced by everyone we manage COVID19 rather than allowing the virus to play the role of manager.

Masks: Effectiveness of Different Masks, Tips on Making DIY Masks

NPR's Maria Godoy did a review June 21 of one of these: masks, how they help and why. 

Godoy emphasized again--a point worth repeating--that "Researchers emphasize there are two main reasons to wear masks. There's some evidence of protection for the wearer, but the stronger evidence is that masks protect others from catching an infection from the person wearing the mask. And infected people can spread the virus just by talking."

Godoy cited Linsey Marr (Virginia Tech) on the power of addition during this pandemic. "'I think we need a combination of [masks,] distancing, avoiding crowds, avoiding poorly ventilated spaces.'" Godoy continues that "Even if each of those individual measures is only partially effective," according to Marr, "'by the time you add them all on top of each other, you can achieve better numbers for reduction of transmission.'"

Here is a brief summary on the effectiveness of the various masks.
--N95 masks protect both the wearer and other people, BUT are in short supply and should be reserved for health workers and emergency responders.

--Surgical masks protect people from the wearer. In laboratory tests they block out 75% of respiratory-droplet particles. However even loose-fitting surgical masks block out droplets, more contagious than infectious aerosols, the particles that linger.

--Masks with front valves should be avoided. They let unfiltered air out.

--Cloth masks vary and the protection depends on the materials and how well they fit. They can be made to offer protection to the wearer in the 30% to 50% range.

--Masks must cover both nose and mouth.

We wear masks primarily to protect others but they help us, too. Remember when you talk and breathe, stuff--tiny droplets--are coming out of your mouth and nose.

Godoy's reporting includes the details includes a video (3m 30s) with tips for improving the design of DIY masks.

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