What are the health effects associated with carbon monoxide?

The effects at low concentrations include fatigue in healthy people and chest pain in people with heart disease; effects at higher concentrations include impaired vision and coordination, headaches, dizziness, confusion, and nausea.

CO can cause flu-like symptoms that clear up after leaving home. At very high concentrations, CO exposure is fatal. Acute effects are due to the formation of carboxyhemoglobin in the blood, inhibiting oxygen intake. At moderate concentrations, the result may be angina, impaired vision, and reduced brain function.