Smoking is a cause of various serious and fatal diseases such as lung cancer, emphysema, chronic bronchitis, and heart disease. In spite of knowing the risks, many people find it very difficult to quit smoking.
The health risks of smoking are identified through epidemiology – a statistics-based science that deals with risks among large groups of people rather than individuals.
Over many years, epidemiological studies have consistently reported a much higher incidence of certain diseases among smokers than non-smokers. The studies also report that risks are reduced after smokers quit and that quitting earlier has by far the greatest impact on risk reduction.
Traditionally, epidemiology has been used to identify associations that point to possible causes of a disease, providing direction for thorough laboratory investigations. With smoking, laboratory investigations over the years have proved more problematic. Science has not yet been able to identify biological mechanisms that can explain with certainty the statistical findings linking smoking and certain diseases, nor has science yet been able to clarify the role of particular smoke constituents in these disease processes.
This means that science is not yet able to determine which smokers will contract a smoking-related disease and which will not. Nor can science tell whether any individual became ill solely because they smoked. This is, in part, because all the diseases that have been associated with smoking also occur in life-long non-smokers.
We do not point out these scientific limitations to cast doubt that smoking is a cause of serious disease. They do, however, create challenges with respect to efforts to design less harmful cigarettes. British American Tobacco's own work over many years has included, and still includes, research into the assessment of potentially less harmful cigarettes and it remains committed to this work, although the lack of complete understanding about the biological aspects of disease mechanisms and the role of particular smoke constituents make answers harder to find.
What people should consider about the risks:
Smoking is a cause of various serious and fatal diseases. The health risks in groups vary by the amount smoked, being highest in those who smoke for more years and smoke more cigarettes per day. The risks go down in groups of people who quit smoking, more so in those who quit sooner rather than later. Experts advise there should be no smoking during pregnancy.
The only way to be certain of avoiding the risks of smoking is not to smoke.