Exhaled carbon monoxide level for non-smokers is typically less than which value?

Exhaled carbon monoxide level for non-smokers is typically less than which value?

• A. <5
• B. <8
• C. <9
• D. <7

Answer: (D)

Exhaled carbon monoxide level reflects recent exposure to cigarette smoke. In people who do not smoke, inhaled CO is very low, so the exhaled CO stays at a minimal level. The typical upper limit for a non-smoker is under seven parts per million. This threshold helps distinguish non-users from smokers, who usually have higher exhaled CO due to ongoing exposure. Environmental exposure can cause small increases, but values generally remain below this level in non-smokers. CO clears from the body relatively quickly, so this measurement reflects recent smoking status.

Exhaled carbon monoxide level reflects recent exposure to cigarette smoke. In people who do not smoke, inhaled CO is very low, so the exhaled CO stays at a minimal level. The typical upper limit for a non-smoker is under seven parts per million. This threshold helps distinguish non-users from smokers, who usually have higher exhaled CO due to ongoing exposure. Environmental exposure can cause small increases, but values generally remain below this level in non-smokers. CO clears from the body relatively quickly, so this measurement reflects recent smoking status.