Carbon monoxide isn't a big problem. According to the Journal of the American Medical Association, carbon monoxide is the leading cause of accidental poisoning death in the country, responsible for 1,500 accidental deaths and over 10,000 illnesses annually. Carbon monoxide has an odor. Carbon monoxide is odorless, colorless and tasteless. It can kill you before you even know it's there.
Natural gas contains carbon monoxide.
New homes are safe from carbon monoxide problems. Carbon monoxide only comes from car exhaust. Carbon monoxide is present in car exhaust fumes, but it is also produced by many common home appliances such as gas or oil furnaces, water heaters, space heaters or clothes dryers. Barbecue grills, fireplaces, wood burning stoves and gas ovens are other possible sources. Carbon monoxide isn't emitted from fireplaces.