Carbon monoxide (CO) is a highly toxic, colorless, odorless, and tasteless gas, undetectable by human senses and exceptionally dangerous. It forms as a byproduct of incomplete burning of carbon-containing materials. While often associated with faulty appliances or car exhaust, smoking tobacco products is also a direct source of CO exposure.
How Smoking Generates Carbon Monoxide
Cigarettes and other tobacco products produce carbon monoxide through incomplete combustion. This occurs when tobacco burns without enough oxygen to fully convert carbon into harmless carbon dioxide. The smoldering conditions within a burning cigarette are ideal for generating CO, which is then released into the smoke.
When cigarette smoke is inhaled, CO is drawn into the lungs and absorbed into the bloodstream. The amount of CO generated varies depending on the tobacco product, number of cigarettes smoked, and individual smoking behavior. Each puff delivers this toxic gas into the smoker’s respiratory system.
How Carbon Monoxide Affects the Body
Once inhaled, carbon monoxide rapidly diffuses from the lungs into the bloodstream. It encounters hemoglobin, the protein in red blood cells that transports oxygen throughout the body. CO has a significantly higher affinity for hemoglobin than oxygen, binding 200 to 300 times more readily.
This strong bond forms carboxyhemoglobin (COHb), displacing oxygen from its binding sites on hemoglobin. As COHb accumulates, the blood’s capacity to carry and deliver oxygen to vital organs and tissues, such as the brain and heart, is severely reduced. COHb also alters the shape of remaining oxygen-carrying hemoglobin, making oxygen release more difficult where needed. This dual mechanism leads to cellular hypoxia, or oxygen deprivation, throughout the body.
Recognizing Carbon Monoxide Exposure
Symptoms of carbon monoxide exposure can be subtle and are often mistaken for common ailments like the flu or fatigue. Common indicators include headaches, dizziness, weakness, nausea, confusion, chest pain, shortness of breath, and malaise.
For smokers, recognizing these symptoms is particularly challenging. Many signs might be attributed to smoking effects or pre-existing conditions, delaying the realization that CO exposure is occurring. Exposure can happen without immediate awareness, complicating diagnosis.
Severity and Chronic Risk from Smoking
Unlike acute carbon monoxide poisoning from sources like faulty furnaces, CO exposure from smoking is chronic and sustained. Smokers are continuously exposed to lower, yet harmful, levels of carbon monoxide with each cigarette. While non-smokers typically have carboxyhemoglobin levels below 3%, smokers often have levels ranging from 3% to 8%, and heavy smokers can reach up to 15%.
This persistent oxygen debt profoundly impacts the body, particularly the cardiovascular system. The heart must work harder to compensate for reduced oxygen capacity, increasing the risk of heart attacks and stroke. Chronic CO exposure from smoking also contributes to cardiovascular diseases by promoting plaque formation and restricting blood flow in arteries.
Beyond cardiovascular effects, chronic CO exposure from smoking impairs lung function and reduces exercise tolerance, leading to breathlessness and respiratory issues. It can also lead to impaired cognitive function, memory problems, and difficulty concentrating due to reduced oxygen to the brain. This low-level intoxication exacerbates health vulnerabilities, making smokers more susceptible to other health complications linked to chronic oxygen deprivation.