Tobacco use is the single most preventable cause of illness and death in the world. It harms nearly every organ of the body, causes many diseases and reduces the health of smokers in general. According to the World Health Organization, for the entire 20th Century, it is estimated that around 100 million people died prematurely because of smoking.

Increased health risks

Smokers are likelier than nonsmokers to develop heart disease, stroke and lung cancer. However, smoking can cause cancer in any part of your body and increases the risk of dying from the disease.

Smoking increases the risk of:

Coronary heart disease by 2 to 4 times
Stroke by 2 to 4 times
Men developing lung cancer by 25 times
Women developing lung cancer by 25.7 times
Developing diabetes (30–40% higher for active smokers than nonsmokers)
Cataracts, rheumatoid arthritis and inflammation

Additional impacts:

While breast cancer is the most commonly occurring cancer in women, according to the World Cancer Research Fund International, more women die from lung cancer each year than from breast cancer
Smoking causes stroke and coronary heart disease
Chronic obstructive pulmonary disease (COPD) is the third leading cause of death worldwide, and tobacco smoking accounts for over 70% of COPD cases in high-income countries
Smokers are 12 to 13 times more likely to die from COPD than nonsmokers
Smoking can make it harder for a woman to become pregnant. It can also affect her baby’s health before and after birth
Smoking can also affect men’s sperm, which can reduce fertility and also increase risks of congenital disabilities and miscarriage
Even people who smoke fewer than five cigarettes a day can have early signs of cardiovascular disease

The World Health Organization has found that in several countries in 2017, more than 1-in-5 deaths directly resulted from smoking, including China, Denmark, the Netherlands, Greece, Bosnia and Herzegovina and Greenland. Quitting smoking lowers your risk for smoking-related diseases and can add years to your life.