There are about 4000 known chemicals in tobacco smoke, and most are poisonous or carcinogenic.

Tobacco smoke contains over 40 compounds that are known to be carcinogens. Among these is nicotine. Inhaled nicotine reaches the brain within 15 seconds and concentrations in brain tissue remain high for about two hours. It is transformed by oxidation in the liver to conitine, which is then excreted in the urine where it can be detected by a laboratory test.
When a person smokes a cigarette, the body responds immediately to the chemical nicotine in the smoke. Nicotine causes a short-term increase in blood pressure, heart rate, and the flow of blood from the heart.
It also causes the arteries to narrow. The smoke includes carbon monoxide, which reduces the amount of oxygen the blood can carry. This, combined with the nicotine effects, creates an imbalance between the demand for oxygen by the cells and the amount of oxygen the blood can supply.
Cigarette smoking increases the risk of developing hardening of the arteries and heart attacks in several ways. First, carbon monoxide damages the inner walls of the arteries, encouraging fatty buildups in them. Over time, this causes the vessels to narrow and harden. Nicotine may also contribute to this process. Smoking also causes several changes in the blood that make clots -- and heart attack -- more likely.
According to experts, tobacco is the second major preventable cause of death in the world. It increases the risk of cancer in humans, and smokers are found to have cancers 15 years sooner than non-smokers.
Second-hand smokers will also suffer from heart disease and many serious respiratory and cardiovascular diseases at a rate 25 percent higher than those who are not exposed to smokers.
A total of 50 percent of bladder cancer cases in men and over 30 percent of bladder cancer cases in women are caused by tobacco. Kidney cancer is more common in smokers. The risk of breast cancer in female smokers and female second-hand smokers is greater than for non-smokers.
Tobacco is the only addictive substance readily, cheaply, and legally available to Iranians from all walks of life, Hassan Azaripur of the Iranian Health Ministry’s Committee on Tobacco Control told the Mehr News Agency on the second day of Iran’s No Tobacco Week (May 25-31).
Unfortunately, there is an increase in the number of smokers aged between 16 and 25 in Iran, and 9 million of the country’s 70 million people smoke regularly, he lamented.
Some 25 percent of Iranians over the age of 15 are in danger of becoming smokers, Azaripur noted, adding, “14.1 percent of the country’s smokers are between 13 and 15 years old.”
“Each smoker lights up an average of 16 cigarettes daily,” Health Ministry official Mostafa Qaffari told the Mehr News Agency, adding that most of Iran’s tobacco smokers are between 15 and 64 years old.
“Some 20 percent of all men smoke daily compared to 3 percent of women,” Qaffari stated.
According to the World Health Organization, one in ten deaths among adults worldwide is caused by tobacco. Tobacco caused 100 million deaths in the 20th century. Just in 2005, it caused an average of one death every six seconds. If current trends continue, the death toll is expected to reach over 8 million annually by 2030 and could hit one billion deaths in the 21st century.
About 29 percent of the adult population of the world smoke tobacco. It is more common among men -- 47.5 percent of all men smoke compared to 10.3 percent of all women.
It is common knowledge that half the people who smoke regularly today -- about 650 million people -- will eventually be killed by tobacco.
WHO observes World No Tobacco Day each year on May 31. This year, the theme is “Tobacco-Free Youth” highlighting two critical messages:
1. Tobacco marketing can contribute to disability and death, and
2. A complete ban on advertising, sponsorship and promotion are highly effective measures for tobacco control as they reduce experimentation and initiation in tobacco use.
Unfortunately, the developing world is slow in taking measures in response to health threats like industrial pollution and bad diets, and we see the same thing in regard to smoking.
And in our country, the Iranian Anti-Tobacco Association (IATA), with the cooperation of the National Research Institute of Tuberculosis and Lung Disease (NRITLD), organizes No Tobacco Week each year from May 24 to 31.
The IATA organized a number programs for the anti-smoking week which were meant to raise people’s awareness of the hazardous effects of smoking, to encourage and motivate smokers to quit, and to help enforce the new “Restriction on Tobacco Use and Supply in Public Places” law, which was drafted to prevent the violation of non-smokers’ rights in public places and to maintain public health.
However, even though more official and non-official restrictions have been placed on smoking, the number of young Iranians taking up the habit is increasing.
In addition, many people in Iran and the rest of the world are still unaware of the danger of passive smoking, but concerted efforts to convince people that smoking is harmful to their family members could help to reduce smoking or even encourage people to quit.
And since today is World No Tobacco Day, hopefully some smokers will be encouraged to take the first step in kicking the habit