Carbon monoxide is called the "silent killer" because you can't see it or smell it. That's why you should have a carbon monoxide detector on every level of your home. But when Rossen Reports did spot checks door to door with the St. Paul, Minnesota, fire department, they found that many homeowners don't have them.
Carbon monoxide detectors cost less than $50 at any big box store, and are simple to install; they plug into any outlet and do not need to be positioned high like smoke detectors. Devices that detect both smoke and carbon monoxide are effective as well.