New York City Mayor Michael Bloomberg says that reducing the number of smokers by five percentage points before 2020 could save 100 million lives across the world, the Australian reported on May 18.

"If the world reduces absolute adult smoking prevalence by five percent by 2020, at least 100 million fewer tobacco-related premature deaths would occur in people alive today," Bloomberg and New York City Health Commissioner Thomas Frieden wrote in the British medical journal The Lancet.

Bloomberg, a former smoker, has used $125 million of his own money to launch a Worldwide Stop Smoking Initiative. He and Frieden wrote that reaching this target would require boosting taxes, banning tobacco advertising, expanding smoke-free zones, and helping people quit.

In New York City, Bloomberg has raised tobacco taxes and banned smoking in all public places, including bars and restaurants. The Lancet study concluded that, for every 10 percent increase in the price of tobacco, tobacco consumption is reduced by 2.5 to 5 percent. 

An estimated 25 percent of the world's adults are tobacco users. Two-thirds of the world's adult smokers live in 15 low-income or middle-income nations, with almost half living in five countries: China, India, Indonesia, Russia, and Bangladesh.