What are harmful drugs?
How does smoking cigarettes change the human body? This question can be answered by comparing a healthy body with a smoker's body. First let us look at the body of a person who does not smoke.

When air is drawn into the body it passes down a tube in the lower neck called the windpipe. The lining of this tube is covered in slime, which traps dust particles. There are microscopic hairs below the slime, which waft to and fro. This movement drives the duct particles to the top of the windpipe where they are swallowed. This mechanism helps to keep the surface of the lungs clean.

The lungs of a non-smoker are pink. They are packed with tiny air spaces, which make a very large surface area for absorbing oxygen. Around each air space runs the blood packed with red blood cells. There is a chemical called haemoglobin in red blood cells. It allows the cells to pick up large amounts of oxygen and transport it round the body to all the cells that need it. The power to move the blood is generated in the heart, which beats healthily.

A cigarette is made from ground-up, dried, tobacco leaves. In the leaf is a chemical called nicotine. It is a drug. Also in the leaf are a large number of other chemicals. When the cigarette is lit the nicotine and chemicals pass into the smoke. Forty of these chemicals have the power to change the way cells grow and to turn them into cancer cells. Also in the smoke is a gas called carbon monoxide.

When a person inhales smoke, it flows over the surface of the windpipe and down into the lungs. Some of the substances in the smoke affect the microscopic hairs in the windpipe and make them slow down. After the person has been smoking awhile, the hairs stop moving completely and dust particles are not removed from the air in the windpipe. They collect, as dirt, in the lungs.

When the smoke reaches the lungs, the carbon monoxide passes through the surface of the lungs and into the red blood cells. It attaches itself to the haemoglobin and stops the red blood cells picking up oxygen. Nicotine passes into the blood and speeds up the heart. The other chemicals in the smoke settle on the lining of the lungs and begin to damage the cells.

After a person has been smoking for a short while, they develop a cough. This is due to the collection of dirt in the lungs. The microscopic hairs are no longer performing their task so when large amounts of dirt gather in the lungs the only way the body can remove them is to force the air out of the lungs quickly - in a cough. Over the years a smoker's cough may become worse. The coughing damages the delicate lining of the lungs and destroys many of the tiny air spaces. This reduces the power of the lungs to take in oxygen and the smoker becomes short of breath.

All the time the person smokes, their heart works harder than a healthy heart. This can lead to heart disease. While the heart is slowly becoming diseased other slow changes can take place in the lungs. The chemicals in the smoke kill some of the cells and when new cells grow to replace them the chemicals alter them and turn them into cancer cells. These cells form lumps called tumours which can grow and kill the body.

By comparing the two bodies it is amazing that anyone wishes to smoke. The problem is that people may just start to smoke because their friends do. Then they find that they need the sensation that nicotine gives them. When this happens they are addicted to smoking and find it very difficult to give up. So how can anyone avoid the perils of smoking? Just do not start smoking in the first place. It could save your life.

What happens to the body if a person has only smoked a few cigarettes and then given up?
The body will recover quickly. Even people who have smoked a long time but then give up can avoid some of the illnesses associated with smoking. The most sensible approach to smoking is simply never to start.

Is alcohol a drug?
Yes, it is. People can become addicted to it but alcohol can also do damage more quickly. Alcohol affects the way nerves send messages around the body. It slows them down. It also makes people change their behaviour. They may become more reckless and put themselves and others at risk. If a person has had too much alcohol they may pass out and become unconscious. The stomach may react to all the drink by vomiting and the vomit may become trapped in the windpipe. When this happens, the person may suffocate.

Why are children particularly at risk to alcohol?
Children have much smaller bodies than adults so only a small amount of alcohol may make a child intoxicated very quickly while it would have a much lesser effect on an adult.

Are alcopops safe to drink?
No. They look like pop but can contain a large amount of alcohol.

When someone has had a lot of alcohol, they may have become drunk but the next day they are sober. Why is this?
One of the jobs of the liver is to destroy poisons. Alcohol is a poison so the liver destroys it. The liver can only work slowly so if a person drinks a large amount of alcohol it stays in the body, affects the nervous system and makes the person drunk. Over the period of a day the liver can destroy all the alcohol and the person is sober again.

If a person drinks large amounts of alcohol regularly can they damage the liver?
Yes, they can. The liver may become inflamed and a disease called hepatitis can develop. In extreme cases some of the liver may become scarred and be unable to destroy alcohol. When this happens the person suffers from the disease called cirrhosis, which can be fatal.

How can solvents be harmful?
Solvents contain chemicals, which affect the nervous system in a similar way to alcohol. The effect does not last as long as alcohol so a person may sniff a solvent many times. Each breath takes in chemicals, which can damage the liver, kidneys, bone marrow and nervous system. Some young people have died when they sniffed solvents for the first time. Some people can become unconscious when they inhale solvents and then choke on their own vomit in a similar way to people who have become unconscious due to drinking too much alcohol.

What about illegal drugs? Are they all dangerous?
Yes, they are. They all affect the nervous system and some can cause mental disorders.
How can people avoid the ill health caused by harmful drugs?
Simply do not take them. If offered cigarettes, alcohol, solvents or illegal drugs just say "No" and walk away.