Cigarette smoking is the single biggest avoidable cause of death and disability in developed countries. Smoking is now increasing rapidly throughout the developing world and is one of the biggest threats to current and future world health. For most smokers, quitting smoking is the single most important thing they can do to improve their health.

Encouraging smoking cessation is one of the most effective and cost effective things that doctors and other health professionals can do to improve health and prolong their patients’ lives. This book will explore the reasons why smokers smoke, how to help them to quit, and how to reduce the prevalence of smoking more generally.

Who smokes tobacco?
Cigarette smoking first became a mass phenomenon in the United Kingdom and other more affluent countries in the early 20th century after the introduction of cheap, mass produced, manufactured cigarettes. Typically, a “smoking epidemic” in a population develops in four stages: a rise and then decline in smoking prevalence, followed two to three decades later by a similar trend in smoking related diseases. Usually, the uptake and consequent adverse effects of smoking occur earlier and to a greater degree among men.

In the United Kingdom there are about 13 million smokers, and worldwide an estimated 1.2 billion. Half of these smokers will die prematurely of a disease caused by their smoking, losing an average of eight years of life; this currently represents four million smokers each year worldwide. Deaths from smoking are projected to increase to more than 10 million a year by 2030, by which time 70% of deaths will be in developing countries.

Stages of worldwide tobacco epidemic. Adapted from Lopez et al. A
descriptive model of the cigarette epidemic in developed countries.
Tobacco Control 1994;3:242-7
The prevalence of smoking among adults in the United Kingdom has declined steadily from peaks in the 1940s in men and the late 1960s in women. However, this reduction in overall prevalence during stage 4 of the epidemic disguises relatively static levels of smoking among socioeconomically disadvantaged groups, making smoking one of the most important determinants of social inequalities in health in the developed world. Smoking has also declined much more slowly among young adults in the United Kingdom. The decline in smoking in the United Kingdom and some other developed countries may now be coming to an end. For example, since 1994 the prevalence of smoking in UK adults has remained at about 28%.

Whereas countries in western Europe, Australasia, and the United States may be in stage 4 of the smoking epidemic, in many developing countries the epidemic is just beginning.

Smoking in low and middle income countries is increasing rapidly —for example,the prevalence of smoking among males in populous Asian countries is now far higher than in Western countries —45% in India, 53% in Japan,63% in China,69% in Indonesia, and 73% in Vietnam.

Adverse health effects
The adverse health effects of smoking are extensive, and have been exhaustively documented. There is a strong dose-response relation with heavy smoking, duration of smoking, and early uptake associated with higher risks of smoking related disease and mortality. Data from 40 years of follow up of smokers in a prospective cohort study of male British doctors show the impact of smoking on longevity at different levels of exposure.

Prevalence of smoking of manufactured cigarettes in Great Britain. Data
from Tobacco Advisory Council (1948-70) and general household survey
(1972-2001)

The strongest cause-specific associations are with respiratory cancers and chronic obstructive pulmonary disease; in numeric terms, the greatest health impacts of smoking are on respiratory and cardiovascular diseases.

Cigarette smoking by deprivation level in Great Britain. Data from general
household survey

Some of the increases in health risk associated with smoking are greater among younger smokers. The risk of heart attack among smokers, for example, is at least double over the age of 60 years, but those aged under 50 have a more than fivefold increase in risk. Smokers are also at greater risk of many other non-fatal diseases, including osteoporosis, periodontal disease, impotence, male infertility, and cataracts. Smoking in pregnancy is associated with increased rates of fetal and perinatal death and reduced birth weight for gestational age. Passive smoking after birth is associated with cot death and respiratory disease in childhood and lung cancer, heart disease, and stroke in adults.

The effect on health services is considerable —for example, an estimated 364 000 admissions and ₤1.5bn ($2.4bn; €2.1bn) a year in health service costs are attributable to smoking in the United Kingdom alone.

Survival by smoking status, according to study of male British doctors
(follow up after 40 years, 1951-91). Adapted from Doll et al