Tobacco smoking kills nearly about 420,000 people a year, making it more lethal than AIDS, accidents, homicides, suicides, drug overdoses, and fire. Smokers are also inhaling other chemicals including cyanide, benzene, formaldehyde, methanol (wood alcohol), acetylene (the fuel used in torches), and ammonia. Smoke also contains nitrogen oxide and carbon monoxide, which are harmful gases.
Smokers in their 30's and 40's have a heart attack rate that is five times higher than their nonsmoking peers. Cigarette smoking may be directly responsible for at least 20% of all deaths from heart disease, or about 120,000 deaths annually. Smoking cigars may also increase the risk of early death from heart disease, although evidence is much stronger for cigarette smoking.
Smoking lowers HDL levels (the so-called good cholesterol) even in adolescents. It causes deterioration of elastic properties in the aorta, the largest blood vessel in the body, and increases the risk for blood clots. It increases the activity of the sympathetic nervous system (which regulates the heart and blood vessels).
Tobacco smoke may increase cardiovascular disease in women through an effect on hormones that causes oestrogen deficiency.
Smoking is the cause of 85% of all cases of lung cancer in 2000, account for 28% of all cancer deaths. Quitting reduces the risk for lung cancer, even well into middle age.
Smoking and smokeless tobacco also cause between 60% and 93% of cancers of the throat, mouth, and oesophagus. Smokers also have higher rates of leukaemia and cancers of the kidney, stomach, bladder, and pancreas. About 30% of cervical cancers have been attributed to both active and passive smoking.
People who smoke a pack a day have almost two and a half times the risk of stroke as non-smokers. Smoking can affect blood vessels in the brain as it does in the heart, increasing the risk for dementia from small or major strokes.
Studies have now linked cigarette smoking to many reproductive problems. Women who smoke pose a greater danger not only to their own reproductive health but, if they smoke during pregnancy, to their unborn child. Women who smoke are at a high risk of infertility in women, ectopic pregnancy and miscarriage and stillbirth, prematurity, and low-birth weight.
Smoking reduces folate levels, a B vitamin that is important for preventing birth defects. Women who smoke may pass genetic mutations that increase cancer risks to their unborn babies.
Men's sexual and reproductive health is not immune from the effects of smoking. Heavy smoking is frequently cited as a contributory factor in impotence because it decreases the amount of blood flowing into the penis. Smoking also reduces sperm density and their motility, increasing the risk for infertility.
Children of smoking mothers are more likely to have more motor control problems, perception impairments, attention disabilities, and social problems than children of non-smoking mothers. Women who breast feed and smoke pass nicotine by-products to their babies, which may contribute to these problems.
Smoking impairs formation of new bone and women who smoke are at high risk for osteoporosis. Postmenopausal women who smoke have 17% greater risk for hip fracture at age 60, a 41% greater risk at 70, and a 108% greater risk at age 90. Smokers have more trouble recovering from spinal surgery.