I had the recent unfortunate news that one of my son's friends father died last week of CO poisoning. Until I took him to the viewing I was unaware that I knew his friend's Mom. This hit too close to home with me.
There are too often too many times that we are exposed to carbon monoxide and are not even aware of it. We don't have to be asleep in the house and have the furnace crack and cause us to be exposed. The garage and sheds are the most dangerous. We often in the winter will turn on the car to "warm it up" while it is the garage. If we do, you MUST keep the garage door open. The exhaust can kill you. You will pass out and die before anyone will know that you are there. The other is the shed. While working on lawn equipment, snowblowers, etc, you must keep the area ventilated. If not, you could be sitting in a death trap.
Lastly, please, if you don't have CO detectors in your home and you have gas or oil or propane appliances, please get them and install them today. And if you have them, make sure they are tested frequently. They may save your life someday!