The disease is rarely reversible once established. The risk of death due to the disease increases with the number of cigarettes smoked. In the last 20 years, the death rate from chronic bronchitis in the UK seems to have been declining steadily. This has been attributed to cleaner air, social improvements, fewer male smokers, a reduction in the tar yields of cigarettes and advances in treatment. Nevertheless, there is some indication that this decline may be less marked than at first appears due to changes in the nomenclature of the diseases involved.
Recent evidence shows that prevalence rates of the disease in men in the UK seem to have peaked.
However, they continue to rise in women. There is evidence of the ill effects of tobacco smoke at all ages. The benefits of stopping smoking The risk of lung cancer, like all other cancers, increases steeply with advancing age. Other factors can cause lung cancer but they are much less important than smoking. They include certain substances used in industry, in particular asbestos.