Smoking tobacco has serious negative effects on human health. Tobacco smoking is the greatest cause of preventable death globally. Half of tobacco smokers die from complications related to smoking. Active smokers are estimated to die an average of 10 years earlier than non-smokers. The World Health Organization estimates that, annually, more than 7 million people die from tobacco-related causes, including 1.6 million non-smokers due to passive smoking. It is further estimated to have caused 100 million deaths in the 20th century.
Tobacco smoke contains over 70 chemicals, known as carcinogens, that cause cancer. It also contains nicotine, a highly addictive psychoactive drug. When tobacco is smoked, the nicotine causes physical and psychological dependency. Cigarettes sold in least developed countries have higher tar content and are less likely to be filtered, increasing vulnerability to tobacco smoking–related diseases in these regions.
Tobacco use most commonly leads to diseases affecting the heart, liver, and lungs. Smoking is a major risk factor for several conditions, namely pneumonia, heart attacks, strokes, chronic obstructive pulmonary disease (COPD)—including emphysema and chronic bronchitis—and multiple cancers (particularly lung cancer, cancers of the larynx and mouth, bladder cancer, and pancreatic cancer). It is also responsible for peripheral arterial disease and high blood pressure. The effects vary depending on how frequently and for how many years a person smokes. Smoking earlier in life and smoking cigarettes with higher tar content increases the risk of these diseases. Additionally, other forms of environmental tobacco smoke exposure, known as passive smoke and third-hand smoke, have manifested harmful health effects in people of all ages. Tobacco use is also a significant risk factor in miscarriages among pregnant women who smoke. It contributes to several other health problems for the fetus, such as premature birth and low birth weight, and increases the chance of sudden infant death syndrome (SIDS) by 1.4 to 3 times. The incidence of erectile dysfunction is approximately 85 percent higher in men who smoke compared to men who do not smoke.
Many countries have taken measures to control tobacco consumption by restricting its usage and sales. They have printed warning messages on packaging. Moreover, smoking bans in public places like workplaces, theaters, bars, and restaurants have been enacted to reduce exposure to passive smoke. Tobacco taxation inflating the price of tobacco products, have also been imposed.
In the late 1700s and the 1800s, the idea that tobacco use caused certain diseases, including mouth cancers, was initially accepted by the medical community. In the 1880s, automation dramatically reduced the cost of cigarettes, cigarette companies greatly increased their marketing, and use expanded. From the 1890s onwards, associations of tobacco use with cancers and vascular disease were regularly reported. By the 1930s, multiple researchers concluded that tobacco use caused cancer and that tobacco users lived substantially shorter lives. Further studies were published in Germany in 1939 and 1943, and one in the Netherlands in 1948. However, widespread attention was first drawn in 1950 by researchers from the United States and the United Kingdom, but their research was widely criticized. Follow-up studies in the early 1950s found that people who smoked died faster and were more likely to die of lung cancer and cardiovascular disease. These results were accepted in the medical community and publicized among the general public in the mid-1960s.
Overview Smoking most commonly leads to diseases affecting the heart and lungs and will commonly affect areas such as hands or feet. First signs of smoking-related health issues often show up as numbness in the extremities, with smoking being a major risk factor for heart attacks, chronic obstructive pulmonary disease (COPD), emphysema, and cancer, particularly lung cancer, cancers of the larynx and mouth, and pancreatic cancer. The immune system is also weakened by smoking, which makes the body more susceptible to infections and takes longer to recover from injuries. Overall life expectancy is also reduced in long term smokers, with estimates ranging from 10 to 17.9 years fewer than non-smokers. About half of men who smoke long-term will die of illness due to smoking.
The association of smoking with lung cancer and COPD is among the strongest, both in the public perception and etiologically. Among male smokers, the lifetime risk of developing lung cancer is 17%; among female smokers, the risk is 12%. This risk is significantly lower in non-smokers: 1.3% in men and 1.4% in women. For COPD, the 25-year incidence of moderate and severe COPD is at least 21% for continuous smokers and 4% for non-smokers, with no difference being reported between men and women.
A person's increased risk of contracting disease is related to the length of time that a person continues to smoke as well as the amount smoked. However, even smoking one cigarette a day raises the risk of coronary heart disease by about 50% or more, and for stroke by about 30%. Smoking 20 cigarettes a day entails a higher risk, but not proportionately.
If someone stops smoking, then these chances gradually decrease as the damage to their body is repaired. A year after quitting, the risk of contracting heart disease is half that of a continuing smoker. The health risks of smoking are not uniform across all smokers; risks vary according to the amount of tobacco smoked, with those who smoke more at greater risk. Smoking so-called "light" cigarettes does not reduce the risk.
Mortality
Smoking is the cause of more than 7 million deaths per year, making it the most common cause of preventable early death. One study found that male and female smokers lose an average of 13 and 15 years of life, respectively, while another measured a loss of life of 7 years. Each cigarette is estimated to shorten life by an average of 11 minutes, though this may vary slightly depending on the contents and brand. More recently, it has been reported to be 20 minutes. At least half of all lifelong smokers die early as a result of smoking. Smokers are three times more likely to die before the age of 70 than non-smokers.
In the United States, cigarette smoking and exposure to tobacco smoke account for roughly one in five, or at least 443,000 premature deaths annually. To put this into context, ABC's Peter Jennings (who would later die at 67 from lung cancer caused by life-long smoking) famously reported that in the US alone, smoking tobacco kills the equivalent of three jumbo jets full of people crashing every day, with no survivors.Never Say Die, an ABC News special by Peter Jennings 6/27/1996 On a worldwide basis, this equates to a single jumbo jet every hour.
A 2015 study found that about 17% of mortality due to cigarette smoking in the United States is due to diseases outside of those commonly linked with smoking. Official estimates may therefore be significantly underestimating the number of deaths currently being attributed to smoking.
It is estimated that there are between 1 and 1.4 deaths per million cigarettes smoked. Cigarette factories are the most deadly factories in the history of the world.
Cancer
The primary risks of tobacco usage include many forms of cancer, particularly lung cancer, kidney cancer, cancer of the larynx and head and neck, bladder cancer, esophageal cancer, pancreatic cancer, stomach cancer, and penile cancer. Tobacco smoke can increase the risk of cervical cancer in women. There may be a small increased risk of myeloid leukemia, squamous cell sinonasal cancer, liver cancer, colorectal cancer, cancers of the gallbladder, the adrenal gland, the small intestine, and various childhood cancers. The possible connection between breast cancer and tobacco is still uncertain.
Mouth
Perhaps the most serious oral condition caused by smoking (including pipe smoking) is oral cancer. However, smoking also increases the risk for various other oral diseases, some almost completely exclusive to tobacco users. Roughly half of periodontitis or inflammation around the teeth cases are attributed to current or former smoking. Smokeless tobacco causes gingival recession and white mucosal lesions. Up to 90% of periodontitis patients who are not helped by common modes of treatment are smokers. Smokers have significantly greater loss of bone height than non-smokers, and the trend can be extended to pipe smokers to have more bone loss than non-smokers.
Smoking traditional cigarettes, e-cigarettes, and heat-not-burn products also affects the salivary cytokine levels needed in immune responses. Traditional cigarettes slightly intensify the immune response in long-term smokers compared to non-smokers, with long-term smokers showing higher levels of IFN-γ than non-smokers. E-cigarettes and heat-not-burn products, while marketed as a healthier alternative, have been shown to inhibit immune response function. Users of these products show lower levels of salivary cytokines, chemokines, and growth factors that function to keep the immune response strong and active in the mouth.
Smoking has been proven to be an important factor in teeth staining. Halitosis or bad breath is common among tobacco smokers. Tooth loss is 2 to 3 times higher in smokers than in non-smokers. In addition, complications may further include leukoplakia, the adherent white plaques or patches on the mucous membranes of the oral cavity, including the tongue.
Head and neck cancer Tobacco smoking is the main risk factor for head and neck cancer. Cigarette smokers have a lifetime increased risk for head and neck cancer that is 5 to 25 times higher than the general population. The person who used to smoke's risk of developing head and neck cancer begins to approach the risk in the general population 15 years after smoking cessation. In addition, people who smoke have a worse prognosis than those who have never smoked. Furthermore, people who continue to smoke after a diagnosis of head and neck cancer have the highest probability of dying compared to those who have never smoked. This effect is seen in patients with HPV-positive head and neck cancer as well. Passive smoking, both at work and at home, also increases the risk of head and neck cancer.
Using tobacco together with alcohol is an especially strong risk factor for head and neck cancer, causing 72% of all cases. This rises to 89% when looking specifically at laryngeal cancer. Smokeless tobacco (including products where tobacco is chewed) is also a cause of oral cancer. Cigar and pipe smoking are also important risk factors for oral cancer and have a dose-dependent relationship, with more consumption leading to higher chances of developing cancer. The use of electronic cigarettes may also lead to the development of head and neck cancers due to the substances like propylene glycol, glycerol, nitrosamines, and metals contained therein, which can cause damage to the airways.
Lung cancer