Second-hand or passive smoke is a proven cause of lung cancer and heart disease, and contains many dangerous chemicals.

There is now conclusive evidence that inhaling smoke from other people’s cigarettes can cause cancer. Second-hand smoke, also known as passive smoke or environmental tobacco smoke, kills over 10,000 people in the UK every year.

Mainstream and sidestream smoke

There are two types of tobacco smoke:

• mainstream smoke, which is directly inhaled through the mouth end of the cigarette, and
• sidestream smoke, which comes from the burning tip of the cigarette.

Second-hand smoke consists mainly of sidestream smoke, which is about four times more toxic than mainstream smoke, although people inhale it in a more diluted form.

This is because sidestream smoke contains much higher levels of many of the poisons and cancer-causing chemicals in cigarettes, including:

• up to three times as much carbon monoxide
• five times more cadmium
• 3-10 times more polycyclic aromatic hydrocarbons
• 10-40 times more Nitrosamines
• about 15 times more benzene
• 40-70 times more ammonia

Find out more

For more information on the dangers of second-hand smoke, have a look at the Second-hand smoke page of our Tobacco section.

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