字幕列表 影片播放 列印英文字幕 (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)
B1 中級 美國腔 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) 20 2 joey joey 發佈於 2021 年 05 月 31 日 更多分享 分享 收藏 回報 影片單字