Cigarettes contain more than 4000 chemical compounds and at least 400 toxic substances.
When inhaled, a cigarette burns at 700°C at the tip and around 60°C in the core. This heat breaks down the tobacco to produce various toxins.
As a cigarette burns, the residues are concentrated towards the butt.

The products that are most damaging are:

• tar, a carcinogen (substance that causes cancer)
• nicotine is addictive and increases cholesterol levels in your body
• carbon monoxide reduces oxygen in the body
• components of the gas and particulate phases cause Chronic obstructive pulmonary disorder (COPD).

The damage caused by smoking is influenced by:

• the number of cigarettes smoked
• whether the cigarette has a filter
• how the tobacco has been prepared

Live Long Life

Research has shown that smoking reduces life expectancy by seven to eight years.

A large body of evidence from epidemiological, case control and cohort studies provides convincing documentation of the causal link between cigarette smoking and health risks. Cigarette smoking is a leading avoidable cause of mortality in India each year. Cigarette smoking accounts one out of every five deaths in India and is the most important modifiable cause of premature death.

Non-smokers and ex-smokers can also look forward to a healthier old age than smokers.

Major diseases caused by smoking

Cardiovascular disease

Cardiovascular disease is the main cause of death due to smoking.
Over years, cholesterol and other fats deposit in the arteries, leaving them narrow, blocked hardened or rigid. When the arteries narrow , blood clots are likely to form.
Smoking accelerates the hardening and narrowing process in your arteries: it starts earlier and blood clots are two to four times more likely.
Cardiovascular disease can take many forms depending on which blood vessels are involved, and all of them are more common in people who smoke.
 

• Coronary thrombosis : a blood clot in the arteries supplying the heart, which can lead to a heart attack. Around 30 per cent are caused by smoking.
• Cerebral thrombosis: the vessels to the brain can become blocked, which can lead to collapse, stroke and paralysis.
• If the kidney arteries are affected, then high blood pressure or kidney failure results.
• Blockage to the vascular supply to the legs may lead to gangrene and amputation.

  Smokers tend to develop coronary thrombosis 10 years earlier than non-smokers, and make up 9 out of 10 heart bypass patients.

Cancer

Smokers are more likely to get cancer than non-smokers. This is particularly true of lung cancer, throat cancer and mouth cancer, which hardly ever affect non-smokers.
The observations relating smoking and lung cancer.

• Ninety percent of lung cancer cases are due to smoking.
• If no-one smoked, lung cancer would be a rare diagnosis - only 0.5 per cent of people who've never touched a cigarette develop lung cancer.
• One in ten moderate smokers and almost one in five heavy smokers (more than 15 cigarettes a day) will die of lung cancer.

  For ex-smokers, it takes approximately 15 years before the risk of lung cancer drops to the same as that of a non-smoker.
  
  If you smoke, the risk of contracting mouth cancer is four times higher than for a non-smoker. Cancer can start in many areas of the mouth, with the most common being on or underneath the tongue, or on the lips.
  
  Other types of cancer that are more common in smokers are:

  • bladder cancer
  • cancer of the oesophagus
  • cancer of the kidneys
  • cancer of the pancreas
  • cervical cancer

COPD

Chronic obstructive pulmonary disease (COPD) is a collective term for a group of conditions that block airflow and make breathing more difficult, such as:

• emphysema - breathlessness caused by damage to the air sacs (alveoli)
• chronic bronchitis - coughing with a lot of mucus that continues for at least three months.

Smoking is the most common cause of COPD and is responsible for 80 per cent of cases.

It's estimated that 94 per cent of 20-a-day smokers have some emphysema when the lungs are examined after death, while more than 90 per cent of non-smokers have little or none.

COPD typically starts between the ages of 35 and 45 when lung function starts to decline anyway

In smokers, the rate of decline in lung function can be three times the usual rate. As lung function declines, breathlessness begins.

As the condition progresses, severe breathing problems can require hospital care. The final stage is death from slow and progressive breathlessness.
 

Other risks caused by smoking

• Smoking raises blood pressure, which can cause hypertension (high blood pressure) - a risk factor for heart attacks and stroke.
• Couples who smoke are more likely to have fertility problems than couples who are non-smokers.
• Smoking worsens asthma and counteracts asthma medication by worsening the inflammation of the airways that the medicine tries to ease.
• The blood vessels in the eye are sensitive and can be easily damaged by smoke, causing a bloodshot appearance and itchiness.
• Heavy smokers are twice as likely to get macular degeneration, resulting in the gradual loss of eyesight.
• Smokers run an increased risk of cataracts.
• Smoker's chances of falling ill is 25 per cent more than non-smokers.
• Smoking stains teeth and gums.