Tobacco smoke contains a stimulant called nicotine which forms a strong physical and psychological chemical addiction. The Centers for Disease Control and Prevention believe that nicotine can be as addictive as heroin or cocaine. Nicotine is a Vasoconstrictor and a nerve toxin and it has been classified as a class I insecticide. 
The addiction is definitely strongest when tobacco smoke is inhaled into the lungs. Several studies have proven that nicotine is typically eliminated from the body within 2 to 3 days, but it is also proven that physical and psychological withdrawal symptoms can last for much longer. 
The Tobacco Plant
Tobacco is a very tall plant with large, sticky leaves. The tobacco leaves are chopped, dried, and prepared for snuff and chewing or smoking in cigarettes, cigars, or pipes. Several varieties of tobacco plant are grown throughout the temperate regions of the world. A species called Nicotiana tabacum, or common tobacco, is native to South America, Mexico, and the West Indies.
There are over 4000 chemicals in tobacco out of which one hundred are identified poisons and 63 are known carcinogens.  Nicotine is often singled out as the most dangerous substance in tobacco but there are others which include:
- Carbon monoxide (found in car exhaust fumes)
- Formaldehyde (used to embalm bodies)
- Ammonia Bromide (a toilet cleaner)
Incidence of Smoking
Each year, an estimated 3,000 nonsmoking Americans die of lung cancer, and 300,000 children suffer from lower respiratory tract infections because they inhaled the so-called “secondhand smoke”. The term “secondhand smoke” refers to inhaling the smoke coming from the cigarettes that someone else is smoking.
More than 5 million children living today will die prematurely because of the decision to use tobacco and smoke cigarettes. More than 3 million people under the age 18 smoke half a billion cigarettes each year and more than a half of them consider themselves dependent upon cigarettes.
The good news is that with rising awareness of the disadvantages of tobacco smoking, since 2002, the number of former smokers in the US has been greater than the number of current smokers.
The History of Tobacco Smoking
The abuse of cigarettes has a really long history. Tobacco smoking, using both pipes and cigars, was common in many Native American cultures. It was a part of the culture of the classic-era Maya civilization about 1,500 years ago. Mayans smoked tobacco and mixed it with lime and chewed it in a snuff-like substance. Tobacco was also used as an all-purpose medicine, and was widely believed to have magical powers, being used in divinations and talismans.
The real cigar became popular in England in the late 1820s and the cigarette appeared in 1828 in Spain.
Health Effects of Tobacco Smoking
The health effects of tobacco smoking are related to direct tobacco smoking, as well as passive smoking, the inhalation of environmental or secondhand tobacco smoke. When cigarette smoke is inhaled, thousands of chemicals get into your bloodstream and travel throughout your body. These chemicals cause damage to different parts of the body:
It is proven that different chemicals in tobacco can cause damage to the macula, which represents the most sensitive part of the retina. The tiny blood vessels can burst through the macula, leading to irreversible damage.  Smoking also causes morphological and functional changes to the lens and retina due to its atherosclerotic and thrombotic effects on the ocular capillaries. 
Smoking is a risk factor for all cancers associated with the larynx, oral cavity and esophagus.  There is no doubt that heavy smokers — people who smoke more than 1 pack of cigarettes a day — have laryngeal cancer mortality risks 20 to 30 times greater than non-smokers. 
Heart and circulation
The two main effects smoking has on the heart and circulation are:
- An increase in your heart rate
- A sharp rise in blood pressure
This happens because nicotine attacks the nerves directly, causing the heart rate to rise and blood vessels to constrict. Since smokers have lungs filled with those dangerous fumes, the heart has to pump harder to get enough oxygen to the rest of the body. Smoking can also increase cholesterol and fibrinogen levels in the blood. The heart and circulation diseases caused by smoking include :
- Coronary heart disease (CHD)
- Peripheral vascular disease (PVD)
Studies report that cigarette smoking has been responsible for approximately 140,000 premature deaths from cardiovascular disease in the US annually, and worldwide, more than 1 in 10 deaths from cardiovascular diseases were attributed to smoking. In the US, smoking accounted for more than a third of all deaths from cardiovascular disease and one fifth of deaths from ischemic heart disease in persons older than 35 years of age. 
There is no doubt that the tar content of the cigarette smoke directly damages the cells in the airways of the lung. This can eventually cause cancer of the lung or larynx. It can also lead to chronic bronchitis and emphysema. Several factors contribute to the development of lung cancer :
- The daily dose of tobacco
- The duration of regular smoking
- The form in which tobacco is smoked
Smoking is linked to the buildup of fatty substances in the carotid artery, the main neck artery supplying blood to the brain, which represents one of the most important factors for developing a stroke. Other dangerous properties of tobacco smoke are :
- Nicotine raises blood pressure
- Carbon monoxide reduces the amount of oxygen blood can carry to the brain
- Cigarette smoke makes the blood thicker and more likely to clot
Each year almost one million Americans have a stroke, and close to 20% of them will die from stroke-related causes. Smoking is a huge risk factor for a stroke.
Smoking has been shown to have harmful effects on all parts of the digestive system, contributing to the development of many diseases such as :
- Peptic ulcers
- Crohn's disease
- Stomach cancer
Liver and pancreas
Almost half of all the bladder and kidney cancers in men are caused by smoking.
Skin and hair
Smoking can damage the skin, mainly the substance called collagen which keeps the skin elastic. Smokers get deeper wrinkles all over their faces because nicotine constricts the tiny capillaries that nourish the skin. Not only that, smokers are also prone to premature thinning and graying of the hair.
Bone and muscles
It is proven that tobacco smoke chemicals are poisons that inhibit the development of the new tissue cells. The tissue of smokers does not get an adequate blood supply to promote healing, thus smokers are at a much higher risk of developing osteoporosis.
Smoking Is Expensive
Beside the fact that smoking causes damage to the health, smoking is a very expensive habit. Smoking a pack of cigarettes a day can cost up to $1,800 dollars a year depending on the country you live in.
According to the Centers for Disease Control and Prevention, the average cost of a pack of cigarettes is $6.28. If you are a heavy smoker and smoke at least 1 pack a day, this price tag translates to close to $2000 per month or almost $2,300 per year. Yes, a decade of smoking will hit you even harder: you will obviously spend close to $23.000 on your habit. However, you could be paying much more, if you live in an area where cigarettes are subject to a higher state tax or even a local tax, such as New York, where the state cigarette tax is the highest in the US at more than $4.00 per pack. 
Calculating the cost of your smoking, you may be shocked to find out what it adds up to over just a few years.
The Dangers of Secondhand Smoking
Passive smoking is breathing in environmental tobacco smoke, which consists of the smoke from the burning tobacco and exhaled mainstream smoke.
The Centers for Disease Control and Prevention claim that about 90 percent of non-smoking people in the United States are exposed to environmental or secondhand tobacco smoke. It is proven that constant exposure to environmental tobacco smoke, at the workplace or at home, nearly doubles the risk of having a heart attack and that smoking is a contributing factor for coronary heart disease, increasing the risk by 25-35%. The American Heart Association's Council on Cardiopulmonary and Critical Care have published a study in which they claim that environmental tobacco smoke is a major preventable cause of cardiovascular disease and death. The statement urges that environmental smoke be treated as an environmental toxin, and that ways be found to protect workers and the public from this health hazard.
The following health problems have been associated with second-hand smoking :
- Asthma in children
- Lower respiratory tract infections
- Lung cancer
- Coronary heart disease.
Secondhand smoke appears to present an equal danger to fetuses.
Smokers continue to smoke in order to avoid withdrawal symptoms, which can be very unpleasant. The withdrawal can bring about physical and emotional changes, which may include:
- Irritability, frustration, depression and/or anxiety
- Difficulty concentrating
- Changed sleeping patterns
- Increase in appetite and weight gain
Withdrawal symptoms are the signs that the body is recovering and getting used to living without nicotine. On average, most symptoms are gone within two to four weeks. Heavy smokers may have some symptoms for a few more weeks.
- You shouldn’t smoke cigarettes at all because smoking even a few cigarettes a day can hurt your health. If you try to decrease the number of cigarettes you smoke instead of stopping it completely, soon you’ll be smoking the same amount again.
- Quitting smoking isn't easy! If you are trying to quit smoking you should know that it takes a lot of effort. Almost half of the battle is knowing that you need to quit.
- There are many ways you can quit smoking, including using nicotine replacement products (gums and patches). Nearly all smokers have some symptoms of nicotine withdrawal when they try to quit.
- Half of all the adult smokers have quit, and you can too! That’s a good news. There are millions of people today who have learned to live and cope stress without a cigarette. Quitting smoking is the best step you can take on your way to a healthy living.
- If you need help, ask for it! Many groups offer written materials, programs, and advice to help smokers quit for good.
- Avoid temptation! In the difficult first few days, you can change your routine to avoid situations where you would usually smoke.