Electric heat here, so not a problem.
I did see a huge problem once though. :shock: :shock: :shock: Many years ago I dropped by the elementary school our sons attended, and found it empty. The janitor was outside, so I asked him what was going on. He said that there had been a malfunction in the furnace, and that carbon monoxide got into the school. Most of the kids had been bussed to the hospital! I went straight there, and couldn't believe what I saw. This school had about 300 students, and it looked like half of them were there. There were kids everywhere, including laying and sitting out on the lawn. The worst cases were inside, but there were about a hundred outside, who weren't too bad off, yet still needed watching. I found my boys, and nephew, and was so happy to find them OK.
Carbon monoxide is heavy, and when it happened, the classes in the lower level were affected the worst. The kids just started falling out of their desks! The teachers were standing, so it didn't get to them as fast as the kids. Luckily the staff was level headed and quick thinking, and they evacuated everyone immediately. Only two students needed to spend the night in the hospital, and everyone else was home by supper.
It could have been so much worse than it was, and I'll never forget that day.