Cannabis poses a greater threat to health than tobacco, lung experts have warned. The warning comes on the day that Home Secretary David Blunkett is due to make a Commons statement about the future of government drug policy. Many young people are simply not aware that smoking cannabis may put them at increased risk of respiratory cancers and infections . Dame Helena Shovelton: The Home Affairs Select Committee has recommended that cannabis is downgraded from a class B drug to class C. This would mean that possession would lead to a caution, rather than arrest. The British Lung Foundation is...