How long after a cigarette should a reading be performed?

How long should you wait to perform a reading after smoking a cigarette?

The answer to this question is subject of some debate, but from over 35 years of experience in breath CO monitoring Bedfont recommend waiting at least 10 minutes after a cigarette to take a breath CO reading. This is to avoid a higher CO reading than is accurate due to CO being left in the lung from the cigarette rather than CO that has been metabolized and secreted back into the lung.