CO strangles the victim by reducing the amount of oxygen that can get to cells and impairing the body's usage of oxygen even if it reaches the cellular level. Victims should be removed from the exposure, though symptoms often persist well after removal from the source. Often the symptoms are similar to those of flu. People who may have been exposed to CO should go to the hospital for a simple blood test. Another option is to check carboxyhemoglobin levels in the blood using a breath CO detector.
Symptoms are related to the exposure level and time of exposure.
Moreover, a person should not be exposed to any one of these three conditions more than once per year. The World Health Organization and Health Canada recommend a maximum exposure of 25 ppm for a one-hour period. Older nonelectronic meters or diffusion tubes are not suitable. Zero the CO meter. This is typically done outdoors in a rural or unpolluted area.