According to the World Health Organization smoking is the second largest preventable cause of disease and premature death. Globally, tobacco products are responsible for 5 million deaths annually. A person dies every 6 seconds from smoking-related diseases including chronic diseases and cancer.
Among its many effects, smoking triggers an immunologic response in arteries and veins which is associated with increased levels of inflammatory markers, such as C-reactive protein and increases in white blood cells. C-reactive protein is strongly associated with lifetime smoking exposure as measured by pack-years. Several studies have shown that such markers predict future cardiovascular events including atherosclerosis.
However, once smokers quit, their risk of future cardiac events and death gradually declines, and within 5 years, smoking-associated inflammatory responses start to return to normal.
Cigarette smoking has also been linked to increased risk of autoimmune diseases, including lupus, rheumatoid arthritis, multiple sclerosis, thyroid, and liver. Autoimmune diseases are immune disorders where the body attacks itself resulting in excessive inflammation and tissue damage.
Considering that cigarette smoke contains over 7000 chemicals, the likelihood that smoking triggers autoimmune and other excessive inflammatory immunological responses makes sense. An example of smoke-induced illness is chronic obstructive pulmonary disease (COPD) in which a person has difficulty in getting enough air.
The lungs, in response to cigarette smoke, activate cells lining the lungs and immune cells, resulting in inflammatory responses. If an individual is infected with a bacterial or viral infection in addition to the smoke assault, it results in a vicious cycle of more difficulties in breathing and greater inflammation. Studies have indeed shown that patients with COPD have autoantibodies and inflammatory responses against lung cells.
Researchers have reported that in female smokers, physical activity, known to help reduce inflammation, reduced their relative risk of developing lung cancer by more than 65 percent.
Thus, it might be expected that if smokers were better able to control their inflammatory responses and return to immune homeostasis, that they might be less likely to develop chronic diseases.