Thread by @bopinion

You don’t need to drive far from home to see lawn signs calling to “Unmask Our Kids."

This fall, schools will be open across the country. Some districts are requiring masks, some aren’t. Which side of the debate is right? trib.al/bRGAPoW

Although we’ve spent a lot of time thinking about the harm done by Covid-19, we’ve done little to assess the harm that masks can do.

A recent letter in JAMA raised awareness about a crucial issue: Our kids are breathing air that’s full of carbon dioxide trib.al/bRGAPoW

Initially, the argument for masks was that they kept the wearer from infecting others. Nowadays evidence of the benefits is plentiful.

What the JAMA letter argues is that in considering whether to mask schoolchildren, we must weigh the benefits and risks trib.al/bRGAPoW

The authors, six European researchers, measured CO2 levels in the air inhaled and exhaled by 45 children with a mean age of 10.7. They took readings without face masks, then with face masks of two different types: surgical masks and filtration masks trib.al/bRGAPoW

The results are worrisome.

After just three minutes of mask wearing, the carbon dioxide content of the air inside the masks — the air the children were breathing — was on the order of 13 times what previous research suggests is safe trib.al/bRGAPoW

If the average school day is six hours long, the children would be masked for close to 360 minutes.

And beyond the classroom, parents still struggle to decide when to mask their children and for how long trib.al/bRGAPoW

It’s odd that the issue has had so little public discussion.

Studies published earlier in the pandemic already pointed to potentially higher CO2 levels in health-care workers because they were rebreathing the same CO2 they’ve previously exhaled trib.al/bRGAPoW

The masks seem to be trapping what the lungs are trying to get rid of.

Given that other studies have found similar problems in adults, we should surely be spending more time studying the effect on children trib.al/bRGAPoW

That’s not to say we should accept uncritically the conclusions of the JAMA letter. As the authors admit, the study has its limitations.

Moreover, the experiment was performed in a laboratory; it’s not a study of similar cohorts in the real world trib.al/bRGAPoW

By the same token, mask supporters shouldn’t pounce on these limitations as reason to ignore the study entirely.

We all share the goal of doing what’s best for our children. It’s important to get this right trib.al/bRGAPoW