Cigarette smoke contains thousands of chemicals. The three key substances, though, are:

Nicotine – the addictive ingredient. If tobacco didn’t contain nicotine, nobody would bother smoking it. Nicotine rushes from the lungs to the bloodstream and into the brain within seconds.

It speeds up heart rate and makes receptors in the brain release dopamine. This causes a quick ‘rush’. When someone starts to smoke, his or her brain soon begins to demand nicotine. The more he or she smokes, the more he or she’ll feel the need to. Soon that someone’s a smoker: an addict. When a smoker doesn’t smoke, that smoker feels irritable and anxious. That’s why some people say that smoking relaxes them. They feel less irritable, less anxious, when they smoke a cigarette.

Funny thing is, if they didn’t smoke at all, they’d never have felt that irritable or anxious in the first place: they’d feel that good all the time.

The unpleasant feelings a smoker gets when he/she doesn’t smoke are called withdrawal symptoms. They may seem pretty harsh. But they fade very fast, often within days, when he or she quits.

Tar – toxic junk. Tar is a collective name for thousands of poisonous chemicals. Tar builds up when tiny particles of these chemicals collect in a smoker’s lungs. Tar is called ‘tar’ because it’s black and sticky, like tar or treacle. A heavy(ish) smoker takes about 0.7kg of tar into his/her lungs every year. Tar is highly carcinogenic – a major cancer causer.

Carbon monoxide – poison gas. Carbon monoxide (or CO) is the stuff that car exhausts pump out. It attaches to the haemoglobin in your blood cells, which is meant to carry oxygen around your body, more easily than oxygen can. The more of it you breathe, the less oxygen is being pumped to your organs. If your organs don’t get enough oxygen, they fail: you die.

Cigarette smoke also contains:
	Acetone: Nail polish remover
	Formaldehyde: Embalming fluid – for preserving corpses
	Hydrogen cyanide: Yes, cyanide