Exhaled Carbon Monoxide (CO) Concentration (by Breath Sample)

What This Test Measures

Carbon monoxide (CO) is a colorless gas produced naturally in the body during normal metabolism. When you exhale, trace amounts of CO can be detected. This test measures the concentration of CO in your exhaled breath, which reflects how well your lungs are functioning and whether you’ve been exposed to sources like tobacco smoke or industrial fumes.

Why It’s Done

Your healthcare provider may order this test if you have symptoms like shortness of breath, chronic lung conditions (e.g., COPD), or if you’ve been exposed to potential lung irritants. It can also help monitor smoking cessation progress or screen for occupational hazards.

How It’s Done

You’ll inhale a small dose of carbon monoxide through a mouthpiece, then exhale into a special device that captures your breath sample. The test takes just a few minutes and doesn’t require fasting or special preparation.

What the Results Mean

Higher-than-normal CO levels may indicate lung damage, smoking, or exposure to toxins. Lower levels might suggest improved lung function after quitting smoking or reducing exposure. Results are compared to standard reference ranges for your age and health status.