Physical Properties
      CO is a colorless, odorless, tasteless, non-irritating, highly toxic gas. In other words, you can't see it, smell it, taste it, or even feel it until it is on top of you.

      CO is slightly lighter than air, and rises with warm air (such as from the furnace or water heater- appliances in the basement that emit CO which rises through the house)

      Once the CO and the rest of the emissions from an appliance such as a furnace cool, CO can settle and disperse uniformly throughout a certain space.

Medical Properties
      Up to 25% of chronic CO poisoning (continued exposure to low-level poisoning- see the CO exposure page) may be misdiagnosed as flu symptoms.

      Once again, CO is a stealth gas- it can kill before you know it's there.

      The human body does not have immunity against carbon monoxide.

      CO takes twice as long to leave the human body as it does to enter.

      CO can build up at low levels before symptoms of CO poisoning begin to appear.

      There are at-risk groups to CO poisoning; those who breathe faster (infants, fetuses, small children) and those who already cannot take in the same amount of oxygen as a healthy adult (elderly, sick, those with respiratory disease) These groups of people can develop symptoms of CO poisoning with lower concentrations of CO present.

      CO displaces oxygen (O₂) in the blood stream and on hemoglobin molecules in red blood cells, essentially suffocating a victim. Carbon monoxide bonds with these hemoglobin molecules in these red blood cells, forming carboxyhemoglobin (COHb) CO acts as an inhibitor for oxygen upon entering the body; it bonds to sites normally reserved for oxygen transport, thus decreasing the amount of oxygen that goes to the different organs in the body. CO is especially dangerous because of hemoglobin's affinity for it; it is 200-300 times higher than that for oxygen.

Symptoms- Quick Facts
      LOW LEVEL CO poisoning- "flu-like" symptoms; headaches, fatigue, nausea, dizziness, confusion, irritability.

      MODERATE LEVEL CO poisoning- vomiting, drowsiness, loss of consciousness

      HIGH LEVEL CO poisoning- seizure, coma, permanent brain damage, ultimately death