Frankly I don't think there are any SIMPLE tests for CO. The easiest is to use a CO home detector. A blood test will show CO also but that isn't simple. CO can be collected and bubbled through lime water; however, CO2 will contaminate the results and few homes have a source of lime water available. In addition, few homes can collect a pure sample of the gas to be analyzed. Most CO detectors on the market are not expensive.
