Cute.
I would mention that my furnace guy told me that Carbon Monoxide builds up in the body. You can have a very small leak from something that doesn't reach the level required to trigger a CM detector but which causes a build up to the level of sickness or death. Have your furnace checked regularly. If you are suffering funky symptoms that you can't figure out, pay attention - are the symptoms better when you leave a place you spend a lot of time (work / home)? Might be something to look into.