What Cigarette Smoke Contains: Combustion, Fine Particles, Tar and Carbon

What Is Actually In Cigarette Smoke?

Cigarette smoke is not one chemical — it is what happens when burning tobacco, paper, and additives combine with air at high heat. That process, called combustion, breaks the original materials down and reassembles them into thousands of new compounds. Health agencies including the National Cancer Institute (NCI) and the Centers for Disease Control and Prevention (CDC) report that tobacco smoke contains more than 7,000 chemicals, including at least 250 known to be harmful and at least 69 known to cause cancer.

Three parts of that mixture come up constantly in lung-health discussions: fine particles, tar, and carbon monoxide. Understanding what each one is — and that no single one tells the whole story — is the goal of this guide.

Get Emergency Help First If You Notice These Signs

Some symptoms need immediate medical attention rather than research or reading. Call 911 or go to the nearest emergency room right away if you or someone else has:

• Severe or sudden shortness of breath
• Chest pain or tightness, especially with sweating, nausea, or pain spreading to the arm or jaw
• Coughing up blood
• Blue or gray lips, face, or fingertips
• Confusion, fainting, or extreme drowsiness

These can be signs of a heart attack, a serious lung problem, or another medical emergency. Do not wait to see if symptoms pass.

Why Burning Tobacco Produces a Complex Mixture, Not One Chemical

When tobacco burns, heat breaks apart the plant material, paper, and any added flavorings, then those broken-apart pieces recombine into new substances as the smoke cools. This is why tobacco smoke is described as a mixture rather than a single toxin. The NCI notes that of the more than 7,000 chemicals produced, hundreds are known to be harmful to the body in different ways — some irritate the airways, some interfere with how blood carries oxygen, and some are linked to cancer over time.

That complexity matters for a practical reason: no single chemical in the list, on its own, explains everything smoking is associated with. The particles, gases, and vapor-phase compounds in smoke act on the body together, and researchers study them as a group.

Fine Particles: What Makes Smoke Look and Feel the Way It Does

The visible haze of cigarette smoke is made of countless tiny particles suspended in the gas produced by combustion. These particles are small enough to travel deep into the airways and lungs when inhaled. Because they carry many of the chemicals produced during burning, fine particles are one reason inhaled tobacco smoke reaches areas of the lung that air alone would not affect the same way.

Particle size and concentration can vary by product and how a cigarette is smoked, which is part of why researchers measure smoke exposure in more than one way rather than relying on a single number.

Tar: The Residue Left Behind

“Tar” is the term used for the sticky residue that condenses out of tobacco smoke as it cools — essentially, what is left after the volatile gases are accounted for. It is made up of hundreds of the chemicals produced during combustion, and public health agencies identify it as one of the components most closely associated with the cancer-causing chemicals in smoke. Tar is a mixture, not a single ingredient, and the term is used industry-wide as shorthand for that particulate residue rather than for one specific compound.

Carbon Monoxide: A Gas You Cannot See or Smell

Carbon monoxide is a colorless, odorless gas produced whenever tobacco — or anything containing carbon — burns without complete combustion. It is chemically identical to the carbon monoxide produced by car exhaust or a faulty furnace. Once inhaled, carbon monoxide binds to red blood cells more readily than oxygen does, which reduces how much oxygen the blood can carry to organs and tissues.

Both the CDC and NCI identify carbon monoxide as a component of cigarette smoke connected to cardiovascular strain. The CDC reports that cigarette smoking is a major cause of cardiovascular disease and is linked to roughly one in every four cardiovascular disease deaths in the United States, a risk that involves multiple mechanisms in smoke — not carbon monoxide in isolation.

Fine Particles vs. Tar vs. Carbon Monoxide: A Quick Comparison

• Fine particles: Tiny solid and liquid particles suspended in smoke, formed as burning tobacco and additives combust and cool.
• Tar: Sticky particulate residue containing hundreds of chemicals, condensed from smoke as it cools after combustion.
• Carbon monoxide: Colorless, odorless gas produced by incomplete combustion of tobacco.

People Who Should Use Extra Caution

Exposure to tobacco smoke — including secondhand smoke — is treated as a heightened concern for certain groups:

• Pregnant individuals, because smoke exposure is linked to risks for the pregnancy and developing fetus
• Infants and young children, whose lungs are still developing
• People with existing heart or lung conditions, including asthma and COPD
• Older adults, who may have less cardiovascular or respiratory reserve

If you fall into one of these groups and have questions about smoke exposure, a licensed healthcare provider can give guidance specific to your situation.

What the Evidence Does and Doesn’t Establish

Public health agencies have documented that tobacco smoke contains thousands of chemicals and that many are linked to serious health outcomes over time. What the evidence does not support is attributing a specific health outcome to any single named chemical in isolation, or assuming that avoiding one component of smoke while still smoking eliminates the risks associated with the others. Research in this area also continues to evolve, particularly around how different products, additives, and smoking patterns affect chemical exposure levels.

Frequently Asked Questions

Is tar the same substance used on roads?

No. “Tar” in cigarette smoke is an unrelated term for the sticky particulate residue left behind after tobacco burns. It shares a name with road tar but is chemically different.

Can carbon monoxide from smoking be dangerous even in small amounts?

Public health agencies note that even brief exposure to tobacco smoke can affect the body, since carbon monoxide reduces how efficiently blood carries oxygen. If you have concerns about a specific exposure or symptoms, a healthcare provider or poison control can advise you directly.

Do filtered cigarettes remove these components?

Filters can reduce some particulate matter reaching the smoker, but tobacco smoke remains a complex mixture of thousands of chemicals, including gases like carbon monoxide that filters do not eliminate. This page does not evaluate specific filter or product claims.

Does quitting reduce exposure to these components?

Stopping tobacco use stops ongoing exposure to the smoke produced by burning it. For guidance on quitting methods and support, see our Smoking & Vaping Cessation guide, and talk with a healthcare provider about an approach that fits your health history.

Related Reading

For a broader look at respiratory terminology and general lung-health education, visit our COPD & Respiratory Wellness hub. If you are considering quitting, our Smoking & Vaping Cessation guide covers the products and programs people use. You can also read our full Medical Disclaimer for more on how this site handles health information.

Educational Disclaimer

This article is for general educational purposes only. It does not diagnose or treat any condition and is not a substitute for advice from a licensed healthcare provider. If you are experiencing chest pain, severe shortness of breath, or coughing up blood, call 911 or go to the nearest emergency room.