Smoking is one of the major causes of premature death worldwide. Tobacco is extremely harmful and substances that are inhaled during smoking affect and harm entire body thus affects overall health of an individual.
The tobacco blend is usually made up of dried and processed tobacco leaves and leaf stems. Tobacco contains many harmful chemicals. As soon as one lights a cigarette these chemicals are released in the form of small particles and gases, and come into contact with the body tissues.
Tar is partially burnt tobacco which is black in color and as one smokes it stains the teeth, gums, inner part of the mouth and vocal cords as well. It irritates vocal cords causing cough reflex. It also damages teeth enamel which leads to teeth decay.
As cigarette smoke passes the upper airways and enters the lower airways which are lined by tiny hair like projections called cilia. These tiny hair like projections beat in order to move bacteria and debris out of the lungs. Harmful gases from the cigarette smoke paralyze these brush like cilia. There are large numbers of oxidizing chemicals in cigarette smoke which are highly reactive, and can potentially damage body cells. These chemicals damage and thus cause soreness (inflammation) of respiratory airways and lungs over time. People who smoke are at increased risk of developing lung infections as well as long-term lung conditions such as, emphysema (destruction of air sacs), chronic bronchitis (long-term inflammation that affects the inner lining of air ways), chronic obstructive pulmonary disease (COPD is a type of lung condition which is characterized by long-term breathing problems and poor air flow) and potentially lung cancer etc. Furthermore, children whose parent smoke are prone to develop asthma (It is a chronic inflammatory respiratory condition which occur due to soreness and narrowing of the airways) and respiratory tract infections.
The oxidizing chemicals also react with the inner lining of the blood vessels causing inflammation and fatty plaque deposition inside the vessels. These fatty plaques narrow the blood vessels compromising the circulation. If the critical blood vessels supplying the vital organs such as heart or brain, get damaged or blocked as a result of injury caused by the oxidizing chemicals one may encounter heart attack (It is a medical emergency which occurs when heart muscles get damaged as their blood supply is severely compromised) or stroke (It refers to death of the brain tissue often leading to permanent disability).
These toxic chemicals travel through the blood stream to other body parts of the body and significantly increase risk of developing cancers such as skin cancer, liver cancer, kidney cancer, bladder cancer and pancreatic cancer etc.
Furthermore, other health risks are also associated with smoking such as risk of developing type-2 diabetes, decreased immune function; it also affects sexual and reproductive functions etc.
One of the ingredients present in tobacco is nicotine which makes people so addicted to this chemical. It is a mood-altering drug, within a few seconds of smoking nicotine rich blood from the lungs travels to brain and causes release of certain chemicals which lead to activation of brain reward and alertness systems. For a while people may feel energized, focused and relaxed after smoking but soon this effect wears off as nicotine only stays in the body for few hours, and one can experience cravings just few hours after the last smoke. With time brain develops tolerance for nicotine and so people find smoking very difficult to quit. Nicotine withdrawal symptoms may include restlessness, anxiety, frustration, anger and sleep problems.
According to the studies conducted in 1980s, smoking causes 25% of death among women and men 35 to 69 years of age in the United States of America. Rate of death from vascular disease (It refers to any abnormal condition of the blood vessels) have decreased substantially since 1980s owing to reductions in smoking and in other risk factors and to improved treatment.
Recently, scientists conducted studies with an objective of direct measurement of current risks of smoking and benefits of cessation at various ages as they were uncertain about the data from previous studies.
To conduct the analysis, researchers obtained smoking and smoking-cessation histories from 113,752 women and 88,496 men who were 25 years of age or older. Scientists comment that their analysis classified former smokers who had quit within 5 years before death as current smokers, participants were classified as former smokers if they had smoked at least 100 cigarettes in their life time but had not smoked within the previous 5 years, and participants were classified as never having smoked if they had smoked fewer than 100 cigarettes in their life time. The participants were interviewed between 1997 and 2004 in the U.S. National Health Interview Survey. Researchers related these data to the causes of deaths that occurred by December 31, 2006 (8236 deaths in women and 7479 in men).
Results of the studies have shown that participants who were 25 to 79 years of age, the rate of death from any cause among current smokers was about three times that among those who had never smoked. Moreover, it was noted that among smokers death mostly occurred due to neoplastic, vascular, respiratory and other diseases that can be caused by smoking. [Neoplastic diseases refers to medical conditions that cause tumor growth- both benign (noncancerous) and malignant (cancerous)].
Furthermore, the probability of surviving from 25 to 79 years of age was about twice as great among those participants who had never smoked when compared to participants who were classified as current smokers (70% Vs 38% among women and 61% Vs 26% among men). Life expectancy was shortened by more than 10 years among current smokers when compared with those who had never smoked.
Moreover, adults who had quit smoking at 25 to 34 years of age, 35 to 44 years of age or 45 to 54 years of age gained about 10, 9 and 6 years of life respectively, when compared with those who continued to smoke.
The studies enabled researchers to conclude that cessation of smoking before the age of 40 years reduces the risk of death associated with continued smoking by about 90%, while smokers lose at least one decade of life expectancy when compared with those who have never smoked.
21st-Century Hazards of Smoking and Benefits of Cessation in the United States