Carbon monoxide is a poisonous, colorless and odorless gas. It is harmful when it is breathed in because it displaces the oxygen in your blood and will eventually cause your heart, brain, and other important organs to be deprived of the oxygen they need to operate properly. Some of the first symptoms of carbon monoxide poisoning include headaches, fatigue, dizziness, and nausea. If you’re experiencing prolonged exposure to C02, you may have symptoms like vomiting, confusion and collapsing. It is important to note that carbon monoxide poisoning can be reversed if it is caught fast enough.