It is widely accepted that smoking is the leading cause of lung cancer and smoking cessation remains the most effective method of reducing its incidence. Although attempts to reduce smoking rates have been relatively successful in the Western world, there is a lag of 20 years or so between reducing smoking and reducing the incidence of lung cancer. Despite the recent reduction in smoking rates seen in some countries (particularly in men), further education on the harmful effects of smoking as well as smoking-cessation programmes are urgently required and efforts need to be intensified (see chapter 8) . It is recognised that exposure to environmental tobacco smoke is also associated with lung cancer risk (see chapter 9). Therefore, uniform policies on the banning of smoking in public places are required and their implementation needs to be assured in all countries.
Asbestos is a known carcinogen and its combination with cigarette smoking confers a greater than 40 times increased risk of lung cancer. Despite this, a worldwide ban on asbestos use is not in force and is urgently required (see chapter 7).