NEW YORK --Health officials launched the second round of a graphic ad campaign Thursday that is designed to get smokers off tobacco, saying they believe the last effort convinced tens of thousands to quit.The ads feature sad, real-life stories: There is Terrie, a North Carolina woman who lost her voice box. Bill, a diabetic smoker from Michigan who lost his leg. And Aden, a 7-year-old boy from New York, who has asthma attacks from secondhand smoke."Most smokers want to quit. These ads encourage them to try," said Dr. Tom Frieden, director of the Centers for Disease Control and Prevention.The CDC campaign cost $48 million and includes TV, radio and online spots as well as print ads and billboards.The spending comes as the agency is facing a tough budget squeeze, but officials say the ads should more than pay for themselves by averting future medical costs to society. Smoking is the leading cause of preventable illness and death in the United States. It's responsible for the majority of the nation's lung cancer deaths and is a deadly factor in heart attacks and a variety of other illnesses.Last year's similar $54 million campaign was the agency's first and largest national advertising effort. The government deemed it a success: The campaign triggered an increase of 200,000 calls to quit lines. The CDC believes that it likely prompted tens of thousands of smokers to quit based on calculations that a certain percentage of callers do actually stop.