Smokers who switched to low tar cigarettes to avoid getting lung cancer are catching the wrong end of the stick. And with serious consequences. This is the outcome of a study of lung cancer cases in Switzerland which reveals that brands low in tar are typically inhaled more deeply than stronger cigarettes because they are less irritating to the body's airways. The study indicates that a switch to low tar cigarettes brings down the risk of cancer in the main airways. However, it also reveals that the switch leads to a build-up of tar and the development of tumours deep in the lungs.