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  • (offbeat uplifting music)

  • - [Narrator] Schools used to look like this,

  • classrooms packed with students,

  • lunchrooms full of loud conversations,

  • and teachers just trying to catch a break in the lounge.

  • It's a scene that now looks prime

  • for the spread of the coronavirus.

  • - You have a lot of people together

  • in one space for a long period of time

  • without masks.

  • We don't know if the ventilation's any good,

  • and with activities like shouting,

  • those are all the ingredients for a super-spreading event.

  • - [Narrator] That's why now, school looks very different.

  • Many schools are only partially open for in-person learning,

  • and others are still fully remote.

  • - It's not business as usual,

  • everything has changed.

  • - [Narrator] Elia Valdes has been back

  • in her classroom since October.

  • - I was very concerned about health issues.

  • I knew that this was the best thing for students,

  • to go in physically, 'cause that's hands-down,

  • they will always perform better.

  • - [Narrator] With the virus still spreading,

  • can schools reopen safely?

  • What are the risks of catching COVID there,

  • and how do control measures,

  • like wearing a mask or increasing ventilation

  • change that picture?

  • Let's look at the classroom, lunchroom, and break room.

  • - Classrooms are one place where you have

  • a lot of people in the room for a long period of time,

  • that's pretty risky.

  • - [Narrator] This is particularly true

  • for adults or older kids.

  • - Age really matters in terms of transmission,

  • both in terms of acquisition of COVID,

  • as well as transmission of SARS-CoV-2,

  • the virus that causes COVID.

  • - [Narrator] Studies have found,

  • that compared with adults,

  • children might be infected less often,

  • are less likely to show severe symptoms,

  • and are less likely to be hospitalized

  • for severe infection.

  • That said, the risk isn't zero, even for younger kids.

  • We know that the virus is transmitted

  • in a variety of ways.

  • Large droplets exchanged in a close range,

  • small droplets lingering in the air,

  • and indirectly through contact with a contaminated surface.

  • - If somebody who is infected with COVID

  • comes into a classroom

  • and there's no control measures in place,

  • then they're sitting there breathing and talking,

  • and they're releasing virus into the air.

  • - [Narrator] Think of the virus forming a small cloud

  • in front of the infected person.

  • Larger, virus-laden droplets

  • expelled from the nose or mouth,

  • would fall nearby, while the smaller droplets

  • would float further away,

  • and that's just from talking normally.

  • - By shouting and screaming and being emotional,

  • you can give these droplets superpowers,

  • make them smaller, which we call aerosol,

  • and can fly further, 10, 20 feet in some cases.

  • - It's gonna kinda fill the room eventually,

  • especially if that room is poorly ventilated,

  • and then everyone else in that room

  • is going to be exposed to it,

  • and they'll be forced to breathe it.

  • - [Narrator] But this picture changes dramatically

  • when control measures are put in place.

  • Experts say the most important one is masking.

  • With masks on everyone, the infected person

  • would release less virus into the air.

  • And the others would have some protection

  • against the virus that remains.

  • - I would say the second most important thing

  • is to ensure good ventilation of the classroom.

  • It could be as simple as opening some doors and windows.

  • - [Narrator] Doing so helps replace

  • the air inside the classroom,

  • bringing in clean air from outside.

  • That can remove or reduce the virus in the room,

  • lowering the risk of transmission.

  • Physical distancing is another way to mitigate risk.

  • The CDC used to recommend six feet,

  • but it's since changed it to three.

  • - There's not a magic number for safe versus unsafe,

  • but the farther apart people are, the better,

  • so that they're kind of out

  • of each other's directly exhaled breath.

  • - [Narrator] A study of Massachusetts Public Schools

  • found that case rates

  • in schools maintaining three feet of distance

  • were similar to those of schools using six feet.

  • Prevention gets more complicated in the lunchroom.

  • - So in the lunchroom setting, it's virus heaven.

  • The virus is in paradise because they have so many ways

  • to infect noses and mouths.

  • - [Narrator] That's because to eat,

  • students need to take off their masks,

  • taking away a key control measure.

  • To compensate, experts recommend

  • adding portable air cleaners

  • with HEPA filters, if possible.

  • - The portable air cleaner works

  • by pulling air through it and passing it through

  • a really high quality filter

  • that filters out and removes all the aerosols

  • that are in the air and all the virus

  • that they might contain.

  • And then out the other side of the portable air cleaner

  • comes nice, clean, virus-free air.

  • - [Narrator] In the teacher break room,

  • cleaning the air is also really important,

  • because it's only adults.

  • - Adults, of course, breathe more than kids do

  • and produce probably even per breath,

  • produce more aerosols.

  • And so let's say someone's sick,

  • well an adult is probably gonna release more virus

  • into the air, and the other adults in that room

  • are gonna be breathing more of that air compared to kids.

  • - [Narrator] Surface cleaning

  • and hand-washing are all important here,

  • just maybe not as critical as was initially thought.

  • - Excessive attention to surface cleaning

  • is taking away time and energy

  • from cleaning the air, which is gonna be more important

  • for reducing the risk of transmission in schools.

  • - [Narrator] For teachers, vaccination

  • is the latest control measure, and most states

  • are giving K through 12 educators priority.

  • - I just recently got my vaccine,

  • so that makes me feel a lot better.

  • - [Narrator] Even with a vaccine,

  • limiting teacher interactions with students is important.

  • - What can you do?

  • - [Narrator] Because it's still unclear

  • if vaccination stops transmission.

  • And studies have shown adults are more likely

  • to transmit the virus than younger kids,

  • for whom vaccines aren't authorized yet.

  • - I would always greet my students at the door.

  • Hello, how are you, come on in.

  • Sit down, some of them would give me hugs.

  • Oh, Miss Valdes, high five.

  • Now it's like elbow or nope, social distance, remember,

  • we can't get close to one another.

  • - [Narrator] Experts say the key is not relying

  • on any one control strategy.

  • Masking, distancing, ventilation, vaccination,

  • and testing all have a role to play

  • in how schools reopen.

  • - So to try and keep everything all at once,

  • and that laundry list in place,

  • it's probably going to be very frustrating for many people.

  • And I think if you had to do one thing,

  • it's probably going to be wearing that mask.

  • (uplifting music)

(offbeat uplifting music)

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实施 Covid-19 控制的教室有多危险(How Risky Is the Classroom With Covid-19 Controls in Place? | WSJ)

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    joey joey 發佈於 2021 年 05 月 31 日
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