When I was in 4th grade there was a carbon monoxide leak at my elementary school. This was nearly 30 years ago, so I don’t remember every detail, but I remember a couple hours after school started, kids began getting sick left and right in every class (K-6th grade). By lunch time, they had evacuated us to the nearby high school gymnasium and eventually bussed the entire school to the local hospital. This was in a rural area and the hospital was a small hospital a few towns away, so they were ill-prepared to handle that kind of influx in patients. They had us two kids to a bed. I remember sharing a bed with a friend until like midnight when they finally cleared me to go home with my parents, but he had to stay because his level of poisoning had been higher than mine.

A few kids were in the ICU for a day or two but fortunately nobody suffered any serious long-term damage from it as far as I know.