Oh god that is heartbreaking.

And yes to add - I remember hearing over the years cautionary tales about similar to the story posted.
It seems excessive, but you’ve got to keep in mind what kids of that age are like - may be very self conscious about their bodies, may be very worried about the idea of someone saying they smell or of it being used as ammunition by bullies, and well not take caution in ways that adults would automatically. I seem to remember in the story I heard it mentioning a boy who may have had OCD, so factoring that in as well.

Normally the room will still be ventilated enough and they would cough or feel woozy and eventually stop. But you just need the wrong set of factors occurring together to risk it ending tragically.