Two of the world's richest men have launched a campaign aiming to tackle smoking in the developing world. New York City Mayor Michael Bloomberg and Microsoft founder Bill Gates warn one billion people could die this century from smoking-related illnesses. The billionaire philanthropists have pledged $500m (£250m) in the next five years to help people quit smoking. The two men want to run public-information campaigns warning of the dangers of tobacco. There are more than 1 billion smokers worldwide.