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Smoking and Tobacco

Carbon Monoxide Effect on Lungs

03/11/1997

Question:

What exactly does carbon monoxide do to your lungs?

Answer:

Carbon monoxide is only one of approximately 4000 chemicals contained in cigarette smoke. Carbon monoxide is considered a poison because it blocks your body's ability to use oxygen, thereby, suffocating all of the tissues of your body. The carbon monoxide binds tightly to hemoglobin in your bloodstream once it is inhaled into your lungs. The hemoglobin is a special protein in your red blood cells that normally carries oxygen to all parts of your body. When carbon monoxide is carried by the hemoglobin, this limits your oxygen supply. Since your body contains more than four million red blood cells, there is a considerable amount of hemoglobin in those cells that can continue to carry oxygen, so you don`t feel the effects of a lack of oxygen from a single cigarette. Over time, however, your body produces additional blood cells to compensate for the lack of oxygen that has occurred from chronic smoking. These additional cells cause a strain to the heart and circulatory system that can potentially lead to other health hazards.

The direct effects of carbon monoxide to the lungs are from the lack of oxygen to these tissues. The lack of oxygen causes problems such as: 1) stiffening of the lung tissue from scarring resulting in a condition called chronic obstructive lung disease or emphysema, 2) weakening of the alveolar sacs (the area in the lungs where oxygen is taken in by the blood and carbon dioxide is released) causing bronchiectasis, 3) damage to the lining of the bronchial tubes (the passageways for air to get to the alveoli for gas exchange), 4) damage to the hair cells in the bronchial tubes which help rid the lungs of excess mucous and particulates (small particles such as dust, viruses, bacteria, dead cells, etc.).

All of these above-mentioned effects to the lungs are cumulative. The longer you smoke, the more damage that occurs. The good news is that once you stop smoking, these negative effects begin reversing themselves. If you have not had severe damage to your lungs, it is possible for them to return to a healthy nonsmoking state after ten years of abstaining from tobacco.

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Response by:

Margaret C Sweeney, MD
Formerly, Associate Professor of Clinical Family Medicine
College of Medicine
University of Cincinnati