5 things to know about reopening schools safely

With the school year about to get underway, the "CBS Evening News" spoke with Harvard Professor Joseph Allen about what parents need to know before they send their kids back to the classroom during the coronavirus pandemic. Allen — whose team wrote a 68-page playbook for reopening schools — said he worries about the "devastating consequences" of keeping kids out of school, including the possibility of a "lost year" for this generation of children.

CBS News asked Allen about how schools can mitigate risk to allow kids to return to the classroom this year. Here are our top takeaways from that conversation:

Despite his concerns about the consequences of keeping students at home, Allen said, "It can't be schools as usual this fall. We can only go back when community spread is under control, and when aggressive risk reduction strategies are in place within the four walls of the school."

To some extent, Allen said, this will vary by geography. "I put out a report with some colleagues at Harvard that looks at the number of cases per day, per hundred thousand people," he said. "And if you look at these metrics that we've been using now for a long time will tell you when it's okay to open. So someplace like Massachusetts looks pretty good right now, New York looks pretty good. Places like Georgia, it doesn't look good."

One of the most critical safety strategies for schools is reducing the risk of airborne transmission. Allen said the solutions don't have to be complicated: "I think there's a little bit of a misnomer that these strategies have to be cost-prohibitive - even as simple as opening up the window and doors to create the cross-flow and some of that area. Any air that's recirculated has to go through a high-efficiency filter. It's really that simple."

Allen said he hopes "we start to pay attention to the school building, going forward."

"There are some things we're going to put in right now that will go away when we're done with COVID - like Plexiglas barriers - but there's some things that should stay. We know from a larger body of evidence that better ventilation rates for example are associated with better cognitive function, better reading comprehension, better test scores," he said, "and we've neglected our school buildings for decades."

Allen said "without a question," everyone in school should be required to wear a mask. "Even masks that are imperfect — let's say it's 50% efficiency. It'll go through my mask first, and then it goes through your math, 50 and 50 and that'll give you a 75% reduction," he said. "Not quite an N-95, but pretty good. All of these other strategies matter, but the one that drives down risk the most is universal mask-wearing."

One of our viewers, Gail from Youngstown, Ohio, wrote in to ask whether it's safe for children to wear masks 6-8 hours each day. "It's totally safe," Allen said. "There's no downside risk to wearing a mask … unless you have a child who has a preexisting condition, maybe asthma. You should check with your doctor, but for the most part … wearing a mask is perfectly safe."

For parents wondering whether their school is doing enough to reopen safely, Allen said: "You should be getting communication from your school right now about what strategies are in place. My Harvard Healthy Buildings team put out guidance for parents and teachers: 20 questions every parent should ask before you send your kids back to school.

"You'll see the obvious things; hopefully everyone's wearing a mask - they must be wearing a mask," Allen said. "You'll see the cleaning. The thing that's harder to evaluate is something like ventilation, air cleaning, and it's invisible. So what's going to be key here is that the schools are going to have to communicate effectively what strategies are in place. And if they're not communicating it, well it's on us as parents to ask those hard questions and get answers to them."

Some spaces – like school buses and cafeterias – present particular challenges for social distancing. Allen said schools need to get creative and "use all of our extra space." He recommends having lunch "outside when we can do - it out on the field, out in the parking lot, wherever we can do it. You're not going to use your auditorium anymore for these big events, but we'll have some classes get in there."

"It's time to use all of our space get these kids spread out, especially during the times like lunch when their masks have to come down," Allen said.