Tobacco: Behind the Smoke

What Happens When Tobacco Burns?

When a cigarette burns, the tobacco is changed.

The formation of ash and smoke is the proof of this change.

Burning is also called "combustion".


Three elements are necessary for combustion to occur:

  • heat;
  • oxygen; and
  • fuel (e.g. tobacco).

Did you know?

When smoked, a cigarette can reach a temperature as high as 900°C.

Oxygen is present in the air we breathe.

Combustion is referred to as a chemical reaction.

Here is an example of a chemical reaction: a nail getting rusty (the metal oxidizes in the presence of oxygen).

Matter is changed by combustion.

Combustion modifies the order and organization of atoms in chemicals.

Order and organization

Just in the same way building blocks can be put together, taken apart and re-assembled to form a new construction, atoms can be put together, taken apart and re-assembled to form new chemicals.

In combustion, oxygen from the air and intense heat cause the atoms of the chemicals naturally present in the tobacco plant to reorganize into new chemicals.

The example shown here demonstrates this modification using building blocks as an analogy.

When a cigarette burns, the chemicals in the tobacco are changed into new chemicals!

Many of these new chemicals are toxic.

Chemicals found in tobacco plant

  • Sugars
  • Minerals
  • Water
  • Nicotine
  • Proteins
  • Chlorophyll
  • and more...

Chemicals found in dried tobacco

  • Sugars
  • Minerals
  • Water
  • Nicotine
  • Proteins
  • and more...

There are over 4,000 chemicals in tobacco smoke including:

  • Hydrogen Cyanide
  • Tar
  • Formaldehyde
  • Benzene
  • Carbon Monoxide
  • Nicotine
  • and more...

4,000 chemicals

There are more than 2,500 chemicals in tobacco. During combustion, these are transformed into more than 4,000 chemicals, over 70 of which are carcinogenic. It is important to remember that most of the chemicals in smoke are different from those in tobacco! These new chemicals are formed because of combustion (burning).


Smoke is a mixture of gases and suspended particles.


Part of the nicotine in tobacco is transferred to smoke.

True or False?

Tobacco-free herbal cigarettes (made from clover for example) are also harmful to health.

Toxic chemicals are formed during combustion. Tobacco and the herbs used to make herbal cigarettes are all plants. Many of the chemicals created when tobacco burns are also created when herbs burn. However, nicotine is only present in tobacco.

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