Here are some facts about smoking and lung cancer: • The more you smoke, the more likely you are to get lung cancer but the length of time you have been a smoker is even more important than how many cigarettes you smoke a day; • Starting smoking at a young age is even more harmful than starting as an adult; • Stopping smoking reduces your risk of lung cancer compared to continuing to smoke. The sooner you quit, the better your health - but it's never too late; • Passive smoking (breathing in other people's cigarette smoke) increases the risk of lung cancer, but it is still much less than if you smoke yourself. Some other things increase lung cancer risk. But they increase the risk by only a small amount and far less than smoking. They are: • Exposure to radon gas; • Exposure to certain chemicals; • Air pollution; • Previous lung disease; • A family history of lung cancer; • Past cancer treatment; • Previous smoking related cancers; • Lowered immunity. The most effective measure that can be taken to prevent the development of lung cancer is to stop smoking. Reducing exposure to passive smoking is also an effective method of prevention.