Carbon Monoxide Blood Test in California

What this test measures

Carbon monoxide is an odorless, colorless gas produced by incomplete combustion. Common sources include gas furnaces, water heaters, wood stoves, portable generators, and vehicle exhaust. Because it binds to hemoglobin with high affinity, it forms carboxyhemoglobin and displaces oxygen, which can strain the heart, brain, and other organs. Measuring carboxyhemoglobin gives an objective picture of how much exposure has occurred.

The sample is a blood draw, usually from a vein, and in urgent situations it may be obtained from an artery or analyzed with a co-oximeter. The report gives the percentage of hemoglobin bound to carbon monoxide. People who smoke often have higher baseline levels than non-smokers. Timing matters because carbon monoxide clears from the blood over hours once exposure stops, so a sample collected later may read lower than the peak.

This test is ordered when someone has symptoms that could suggest carbon monoxide poisoning, such as headache, dizziness, nausea, confusion, or shortness of breath, especially when several people or pets in the same building feel unwell. It may also confirm exposure after a known incident or check people who work around combustion equipment. Results guide next steps alongside the clinical assessment.