How is the presence of carbon monoxide measured?

Common methods of measuring carbon monoxide include the use of chemical detector tubes or direct reading instruments employing electrochemical sensors. When using a detector tube to test for the presence of carbon monoxide, either a “grab” sample of the breathing air may be tested or the air may be sampled directly using a specialized kit available by several manufacturers. The tube reading error for most low range carbon monoxide detector tubes ranges from 10-15 percent. Electrochemical sensors can be used for periodic and continuous monitoring of breathing air for the level of carbon monoxide. These sensors must be calibrated periodically (typically on a monthly basis) to perform accurately. The measurement error reported for most electrochemical sensors is 5 percent.