Carboxyhemoglobin level is typically:

Carboxyhemoglobin level is typically:

• A. 0-2%
• B. 0-1%
• C. 1-2%
• D. 2-4%

Answer: (B)

Carboxyhemoglobin forms when carbon monoxide binds to hemoglobin, reducing the blood’s ability to carry oxygen. In healthy individuals with no CO exposure, the amount of Hb bound to CO is very small, so the normal baseline is about 0 to 1 percent. Smoking can raise this baseline somewhat, but the typical normal value used in NBRC context is 0–1%. Levels higher than this suggest CO exposure or significant smoking, making the other ranges outside the normal baseline.

Carboxyhemoglobin forms when carbon monoxide binds to hemoglobin, reducing the blood’s ability to carry oxygen. In healthy individuals with no CO exposure, the amount of Hb bound to CO is very small, so the normal baseline is about 0 to 1 percent. Smoking can raise this baseline somewhat, but the typical normal value used in NBRC context is 0–1%. Levels higher than this suggest CO exposure or significant smoking, making the other ranges outside the normal baseline.