What is the expected COHb level for a smoker?

For a smoker, the expected level of carboxyhemoglobin (COHb) typically falls within the range of 2-12%. This is due to the inhalation of carbon monoxide (CO) present in tobacco smoke, which binds to hemoglobin in the blood, forming carboxyhemoglobin.

In non-smokers, COHb levels are generally very low, often between 0-1%, while chronic smokers can have significantly elevated levels as a result of their smoking habits. This is particularly true as the amount of CO that enters the bloodstream increases with nicotine and other substances found in tobacco products.

A COHb level in the range of 2-12% indicates a moderate exposure to carbon monoxide, reflecting the continuous interaction with tobacco smoke. Values over 12% might indicate more severe exposure or CO poisoning, which is not typical for habitual smokers but might occur in other situations.

In light of this information, the selection of 2-12% as the expected COHb level for smokers effectively captures the common physiological response to chronic smoking, distinguishing it from the lower levels present in non-smokers or occasional smokers.