The CDC estimates that around 400 people die every year due to carbon monoxide exposure. In Minnesota, there is an average of 14 people dying every year due to carbon monoxide.
Carbon monoxide is a byproduct of combustion. Appliances like clothes dryers, water heaters and furnaces can all produce carbon monoxide. Gas powered appliances, like a furnace, need yearly maintenance to make sure they are properly operating and venting.
Now that the weather is changing, and cooler temps are headed our way. The furnace might be firing up for the first time this season. Make sure all fuel burning appliances are properly vented and maintained. Check carbon monoxide detectors to see if they are working properly or if they need to be replaced.
If you plan on having a fire in the fireplace, make sure the chimney is clean and that the smoke is drafting properly up the chimney. Cracking a window nearby can help with creating a strong upward draft when you are having a fire.
Minnesota Department on Health has more info on carbon monoxide poisoning and how to prevent it here.